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Biofloc technology is much highlighted these days because of its tremendous effects on aquaculture. Microbes were enriched on cheapest organic carbon source i. e., powdered banana peels and were incorporated in different aquaria rearing grass carp fingerlings under different C/N treatments (10:1, 15:1 and 20:1) and 10% water daily water exchange. The initial growth of fingerlings was recorded. The experiment was settled in triplicates for 60 days and run parallel to control group provided with commercial feed and daily water exchange. Its effect was evaluated by measuring the growth of fingerlings and water parameters of each aquarium. The average % gain in weight and length of fingerlings was obtained significantly highest (28.12 ± 0.30g and 17.29 ± 0.46cm respectively) in aquaria containing pure powdered banana peels with 10% water exchange and C/N ratio was adjusted at 20: 1 (T3) than other treatments and control. Ammonia and other water parameters were also under control in T3 than other experimental and control groups. By all counts, it was concluded that the highest C/N ratio in biofloc system had the potential to increment C. idella growth rate by reducing toxicity and could be used as fish meal substitute. Resumo A tecnologia Biofloc é muito destacada hoje em dia por causa de seus tremendos efeitos na aquicultura. Os micróbios foram enriquecidos com a fonte de carbono orgânico mais barata, i. e., cascas de banana em pó, e foram incorporadas em diferentes aquários de criação de alevinos de carpa-capim sob diferentes tratamentos C/N (10: 1, 15: 1 e 20: 1) e 10% de troca diária de água. O crescimento inicial dos alevinos foi registrado. O experimento foi resolvido em triplicatas por 60 dias e executado paralelamente ao grupo controle fornecido com ração comercial e troca diária de água. Seu efeito foi avaliado medindo o crescimento dos alevinos e os parâmetros da água de cada aquário. O% de ganho médio em peso e comprimento dos alevinos foi obtido significativamente mais alto (28,12 ± 0,30g e 17,29 ± 0,46 cm respectivamente) em aquários contendo cascas de banana em pó puro com 10% de troca de água e a relação C/N foi ajustada em 20: 1 (T3) do que outros tratamentos e controle. A amônia e outros parâmetros da água também estavam sob controle no T3 mais do que nos outros grupos experimentais e de controle. Por todas as contagens, concluiu-se que a maior razão C/N no sistema de bioflocos tem o potencial de incrementar a taxa de crescimento de C. idella reduzindo a toxicidade e pode ser usada como substituto da farinha de peixe.

3 Figuras.-- 2 Tablas, The impact of the organic carbon to nitrate ratio (C/N ratio) on mixotrophic denitrification rate has been scarcely studied. Thus, this work aims to investigate the effect of the C/N ratio on the mixotrophic denitrification when methanol is used as a source of organic matter and elemental sulfur as an electron donor for autotrophic denitrification. For this, two initial concentrations of NO3--N (50 and 25 mg/L) at a stoichiometric ratio of S0/N, and four initial C/N ratios (0, 0.6, 1.2, and 1.9 mg CH3OH/mg NO3- -N) were used at 25 (±2) °C. The results showed that when using a C/N ratio of 0.6, the highest total nitrogen removal was obtained and the accumulation of nitrites was reduced, compared to an autotrophic system. The most significant contribution to nitrate consumption was through autotrophic denitrification (AuDeN) for a C/N ratio of 0.6 and 1.2, while for C/N = 1.9 the most significant contribution of nitrate consumption was through heterotrophic denitrification (HD). Finally, organic supplementation (methanol) served to increase the specific nitrate removal rate at high and low initial concentrations of substrate. Therefore, the best C/N ratio was 0.6 since it allowed for increasing the removal efficiency and the denitrification rate., Authors would like to acknowledge the financial support provides by FONDECYT (Chile) under Project 1170103 and a PhD fellowship 21200655 awarded to D. Yanez-Sevilla.

The main aim of anaerobic co-digestion of rice straw is to enhance volumetric methane yields and process stability to achieve synergetic effects. However, high carbon to nitrogen ratio of rice straw causes poor process stability for mono-digestion. This study investigated the co-digestion of rice straw and de-oiled rice bran, a nitrogen-rich by-product of the rice milling industry. The spent bio-slurry (having total solids concentration of 2.19%) from running de-oiled rice bran which inherently contains various types of microbes was used as an inoculum for process start-up. A series of experiments were conducted to optimise the methane yield in semi-continuous anaerobic digester operating at 30 days of hydraulic retention time at mesophilic temperature conditions. Co-digestion studies of rice straw and de-oiled rice bran with three different mixing ratios were conducted by maintaining a specific total solids concentration of 5.0, 7.5, and 10.0% total solids concentration for the designated digester. The biogas production, methane contents, volatile matter degradation efficiency were determined to evaluate the stability and performance of the system. The digester maintained at 5% and 7.5% TS showed nearly similar results in terms of methane yield and volatile matter conversion efficiency. During the entire experimentation the percentage of methane content in the produced biogas was in the range of 24.8–55.4%. The average methane yield of 0.169 and 0.173 L/g-VS was found for digester maintained at 5.0% and 7.5% TS respectively. However, the volatile solid mass removal efficiency of 40.13% and 37.94% was recorded for the digester maintained at 5% and 7.5% TS respectively. Since no chemical or thermal pre-treatment was adopted during the entire process it is highly economical and adaptable for concerned industries. Ultimately, the results of the present study were compared to the previous studies on anaerobic co-digestion of RS, which shows the promising result with no extra added input cost.

In this study, we explored the ability of wild-Serbian Ganoderma lucidum mycelial pellets (GLMPs) in treating synthetic domestic wastewater in a batch reactor under various operating conditions. The GLMPs produce non-hazardous by-products, are environmentally sustainable and able to produce in mass bulk with consistent quality. Riding on the highly efficient of treatment of industrial (textile) wastewater using GLMPs, similar high efficiency is foreseen for domestic wastewater as a green alternative treatment process. The optimal performance of GLMPs in similar synthetic domestic wastewater with a Carbon-to-Nitrogen (C/N) ratio of 16.7:1 was evaluated under three operational conditions. The C/N ratio was chosen based on the urban domestic wastewater characteristic during high peak flow with an initial Chemical Oxygen Demand (COD) of 533 mg/L and ammonia–nitrogen (NH3–N) content of 30 mg/L. The operational parameters of agitation speed (0 rpm, 25 rpm, 50 rpm, and 100 rpm), environmental temperature (25 °C, 30 °C, 35 °C, and 40 °C), and GLMP inoculum percentage (GIP) (0%, 0.25%, 0.50%, 0.75%, and 1.00%) were chosen for the experiment. In the experiment, the agitation speed of 100 rpm and the environmental temperature of 25 °C showed the best performance of the GLMPs within 15 h of retention time with a percentage removal of 92.9% for COD and 93.8% for NH3–N. Furthermore, a high volume of GIP in the batch reactor had an insignificant impact on the performance in the same concentration of wastewater, and 0.25% GIP was the volume used to treat the domestic wastewater.

Lacking systematic evaluations in soil quality and microbial community recovery after different amendments addition limits optimization of amendments combination in coal mine soils. We performed a short‐term incubation experiment with a varying temperature over 12 weeks to assess the effects of three amendments (biochar: C; nitrogen fertilizer at three levels: N‐N1~N3; microbial agent at two levels: M‐M1~M2) based on C/N ratio (regulated by biochar and N level: 35:1, 25:1, 12.5:1) on mine soil properties and microbial community in the Qilian Mountains, China. Over the incubation period, soil pH and MBC/MBN were significantly lower than unamended treatment in N addition and C + M + N treatments, respectively. Soil organic carbon (SOC), total nitrogen (TN), available nitrogen (AN), available phosphorus (AP), available potassium (AK), microbial biomass carbon (MBC), and nitrogen (MBN) contents increased significantly in all amended treatments (p 1%) of the bacterial phyla Bacteroidetes and Firmicutes, and decreased the relative abundance of fungal phyla Chytridiomycota (p, The first attempts to combine three amendments to restore mine soils. N2‐treated soil can promote bacterial species richness and diversity restoration. A new insight for mine soil restoration by regulating C/N ratio by amendments

The shallow coastal water zone of the tide-less southern Baltic Sea is dominated by exposed sandy sediments which are typically inhabited by microphytobenthic communities, but their primary production is poorly studied, and hence four stations between 3.0 and 6.2 m depth were investigated. Sediment cores were carefully taken to keep the natural layering and exposed in a controlled self-constructed incubator. Respiratory oxygen consumption and photosynthetic oxygen production were recorded applying planar oxygen optode sensors. We hypothesized that with increasing water depths the effects of wind- and wave-induced erosion and mixing of the upper sediment layer are dampened and expected higher microphytobenthic biomass and primary production in the incubated cores. Our data partly confirm this hypothesis, as cores sampled at the most exposed stations contained only 50% chlorophyll a m−2 compared to the deeper stations. However, primary production was highly variable, probably due to fluctuating sediment-disturbing conditions before the cores were taken. Due to these physical forces sand grains were highly mobile and rounded, and small epipsamic benthic diatoms dominated, which preferentially occurred in some cracks and crevices as visualized by scanning electron microscopy. The data fill an important gap in reliable production data for sandy sediments of the southern Baltic Sea, and point to the ecological importance and relevant contribution of microphytobenthic communities to the total primary production of this marine ecosystem. Oxygen planar optode sensor spots proved to be a reliable, sensitive and fast detection system for ex situ oxygen exchange measurements in the overlying water of intact sediment cores.

A more resilient adaptation to changing climate calls for crop diversification in vineyards, too. As a contribution to the H2020 collaborative project of the European Union, called Diverfarming, and part of the agroecological experiments during 2018 and 2019, grapevine biomass growth was monitored in connection with carbon storage types in soil and in the deposits removed by soil erosion. Phenometry was carried out interpreting segmented images to follow changes in biomass. It was found that crop growth could be best described by the Richards growth function. The distinction between grapevine and intercrop growth, however, requires further refinement in image analysis. In the laboratory TOC and Ntotal were measured for both the soil and the plant organs as well as for the eroded sediments. Greenhouse gas emissions and photosynthesis were monitored. Looking at the change of Leaf Area Index (LAI) over the growing period, image analysis pointed out the role of cut shoots from pruning in the C and N cycles. Maximum leaf area (at ripening) for guyot cultivation technique was extimated at 7,840 m2 ha-1. Soil loss by erosion was established by sediment traps at the end of vinestock rows. The grain size distribution analysis led to the remarkable result that as erosion proceeded, the ratio of the sand fraction increased but remained within the range for the textural class of loam. Organic matter contents grew to 38 g kg-1. The rate of soil erosion is higher in ploughed than in grassed interrows by orders of magnitude.

Azolla algae currently represent a major threat to the environment and rice cultivation fields. Various studies have shown that one of the practical solutions is to turn this threat into an opportunity for biomass energy production. This research investigates the production potential of methane in Azolla. Test was conducted in a completely randomized design (CRD) with Mini Tap software. Three different C/N ratios, 30, 34 and 38, two levels of thermal pre-treatment (raw and steamed Azolla) and two levels of chemical pre-treatment (NaOH 0% and 9%) were used and effects of each case on the methane production rate was studied. The highest amount of methane (247.7 ml·g−1 vs) was produced at C/N ratio of 30 with application of NaOH (9%) and no thermal pre-treatment (raw Azolla). ANOVA analysis showed that interactions of the effective variables were significant, but the trend was not incremental or decreasing; therefore, ANFIS and stepwise regression modelling were used. The results showed that the ANFIS model provides more accurate mapping between the empirical and predicted values than the regression model. Furthermore, among examined models (triangular; trapezoidal; Gaussian; bell-shaped models), the best model for methane production prediction was Gaussian linear membership function (R 2 = 0.997 and ε (%) = 0.32). According to the regression model, the thermal-chemical factor is the most efficient in prediction of the model (b = 35.6).

To date, forest ecology has not made any clear conclusions regarding the impact of large saprophagous invertebrates such as earthworms on soil carbon dynamics. Some authors claim that earthworm activities result in decreased carbon accumulation. Other studies show that earthworms contribute to soil carbon accumulation. At the same time, many studies do not take into account the differences between trophic and digging activity of different morpho-ecological groups of earthworms in different soil horizons. The objective of this study was to carry out differentiated assessment of the impact of different morpho-ecological groups of earthworms on carbon accumulation and correspondent soil parameters (nitrogen content and С/N ratio) throughout the change in forest succession status. Field operations were performed in the spring and summer of 2016 and 2018 in three regions: Bryansk Oblast (Bryansk Forest reserve), Moscow Oblast (Moskva–Oka plain, Valuyevsky urban forest) and Northwest Caucasus (Krasnodar Krai, Apsheron forestry; Republic of Adygeya, Caucasian Biosphere Reserve). Three main stages of coniferous-broadleaf forest restoration after clear cuttings were identified in each region. Three test plots 50х50 m were allocated for each stage; geobotanical and soil descriptions as well as earthworm registration were carried out on each plot. It was found out that during the change in forest succession status the species composition and the set of morpho-ecological groups of earthworms became more complicated, but there was no successive replacement of any groups with others. Ambiguous effects of different morpho-ecological groups of earthworms on carbon accumulation in forest soils were revealed. Negative correlation was found between the total biomass of earthworms feeding on the soil surface (epigeic, epi-endogeic and anecic species) and litter store. In the humus horizon, the biomass of epi-endogeic species was positively correlated with the content of carbon. C/N ratio and nitrogen content are unidirectionally correlated with the biomass of earthworms in the horizons of their activity: with an increase in the biomass of earthworms of different morpho-ecological groups, the C/N ratio decreases, and the nitrogen content increases.

Soil productivity (SP) without external fertilization influence is an important indicator for the capacity of a soil to support crop yield. However, there have been difficulties in estimating values of SPs for soils after various long-term field treatments because the treatment without external fertilization is used but is depleted in soil nutrients, leading to erroneous estimation. The objectives of this study were to estimate the change of SP across different cropping seasons using pot experiments, and to evaluate the steady SP value (which is defined by the basal contribution of soil itself to crop yield) after various long-term fertilization treatments in soils at different geographical locations. The pot experiments were conducted in Jinxian of Jiangxi Province with paddy soil, Zhengzhou of Henan Province with fluvo-aquic soil, and Gongzhuling of Jilin Province with black soils, China. Soils were collected after long-term field fertilization treatments of no fertilizer (control; CK-F), chemical fertilizer (NPK-F), and combined chemical fertilizer with manure (NPKM-F). The soils received either no fertilizer (F0) or chemical fertilizer (F1) for 3–6 cropping seasons in pots, which include CK-P (control; no fertilizer from long-term field experiments for pot experiments), NPK-P (chemical fertilizer from long-term field experiments for pot experiments), and NPKM-P (combined chemical and organic fertilizers from long-term field experiments for pot experiments). The yield data were used to calculate SP values. The initial SP values were high, but decreased rapidly until a relatively steady SP was achieved at or after about three cropping seasons for paddy and fluvo-aquic soils. The steady SP values in the third cropping season from CK-P, NPK-P, and NPKM-P treatments were 37.7, 44.1, and 50.0% in the paddy soil, 34.2, 38.1, and 50.0% in the fluvo-aquic soil, with the highest value observed in the NPKM-P treatment for all soils. However, further research is required in the black soils to incorporate more than three cropping seasons. The partial least squares path mode (PLS-PM) showed that total N (nitrogen) and C/N ratio (the ratio of soil organic carbon and total N) had positive effects on the steady SP for all three soils. These findings confirm the significance of the incorporation of manure for attaining high soil productivity. Regulation of the soil C/N ratio was the other main factor for steady SP through fertilization management.

Experiments were conducted during four consecutive seasons of 2017, 2018, 2019 and 2020 on three grape cultivars including “Bez-El-Anza”, “Thompson Seedless” and “Red Roomy” planted at the Experimental Orchard of fruit section, Faculty of Agriculture, Assiut University in a complete randomized blocked design. This investigation was carried out to study the effect of spraying Seaweed extract, Amino acids and Vitamins on C/N ratio, yield and berry quality of some grape cultivars. The obtained results showed that Tyrosin at 500 ppm recorded the highest yield (9.47 kg/vine) during the 1st season. All treatments had a significant impact in the respect of TSS %, acidity% and TSS/acid ratio. Concerning C/N ratio, Vit.B12 at 150 ppm recorded the highest ratio (44.85) during the 1st season. Hence, the present study concluded applications of Seaweed extract, amino acid and Vitamins improved vine C/N ratio, yield and berry attributes of “Bez-El-Anza”, ‘Thompson Seedless’ and “Red Roomy” grape cultivars.

This study aimed to evaluate decomposition and release of C and of N from the litter of forest Caatinga species in the humification phase, as well as to estimate the residence time of C and N. Litter decomposition of the species was evaluated in 2014/2015 in the municipality of Floresta, Pernambuco, Brazil, using a method of the litter bags at 270; 300; 330; and 360 day. Litter from species of the Fabaceae family presented different decomposition groups, suggesting that decomposition was more influenced by the C/N ratio than N concentration only. The N release was 6.25% greater than the release of C. C will remain in the litter for more time, while N will be almost totally released in approximately 1.14 years. The species litter decomposition were shared, suggesting that the nutrients cycling is fundamental in the preservation of the Caatinga, mainly due to the longer residence time of C.

Rhodosporidium toruloides is a useful oleaginous yeast, but lipids production is affected by various factors including nutrients in the culture medium. Herein, the R-ZL2 high-yield mutant strain was used to investigate the effects of different carbon sources (sucrose, glucose, xylose), nitrogen sources (ammonium sulphate, ammonium nitrate), and C/N ratio on lipids production capacity, get the following conclusion (1) Compared with glucose and xylose, sucrose was a superior carbon source for lipids production; (2) When using ammonium sulphate as the nitrogen source, a C/N ratio of 200:1 achieved the highest biomass, lipids production and lipids content (10.7 g/L, 6.32 g/L and 59%, respectively), and lipids produced under different C/N conditions have potential for biodiesel production (except for C/N = 40 and C/N = 80); (3) When using ammonium nitrate as the nitrogen source, a C/N ratio of 200:1 achieved the highest biomass, lipids production and lipids content (12.1 g/L, 8.25 g/L and 65%, respectively), and lipids produced under different C/N ratio conditions have potential for biodiesel production. Thus, a combination of sucrose and ammonium nitrate was optimal for the lipid accumulation in R-ZL2. The findings will lay a foundation for further improving lipids yields.

Lignocellulosic materials have a complex physicochemical composition and structure that reduces their decomposition rate and hinders the formation of humic substances during composting. Therefore, a composting experiment was conducted to evaluate the effects of different C/N ratios on lignocellulose (cellulose, hemicellulose and lignin) degradation and the activities of corresponding enzymes during aerobic composting. The study had five C/N ratios, namely, T1 (C/N ratio of 15), T2 (C/N ratio of 20), T3 (C/N ratio of 25), T4 (C/N ratio of 30) and T5 (C/N ratio of 35). The results showed that treatments T3 and T4 had the highest rate of degradation of cellulose and hemicellulose, while treatment T3 had the highest rate of degradation of lignin. Among the five treatments, treatment T3 enhanced the degradation of the lignocellulose constituents, indicating a degradation rate of 6.86–35.17%, 15.63–44.08% and 31.69–165.60% for cellulose, hemicellulose and lignin, respectively. The degradation of cellulose and lignin occurred mainly at the thermophilic and late mesophilic phases of composting, while hemicellulose degradation occurred at the maturation phase. Treatment T3 was the best C/N ratio to stimulate the activities of manganese peroxidase, lignin peroxidase, polyphenol oxidase and peroxidase, which in turn promoted lignocellulose degradation.

Based on the improved high-efficiency sewage treatment performance of submerged membrane bioreactors (SMBRs), we focused on how to adjust the C/N ratio of the influent water during reactor start-up to prevent an excessive C/N ratio from causing membrane fouling. In this study, an experimental method of gradually adjusting the influent C/N ratio to quickly start the reactor was proposed, and the results showed that biofilm formation in R1 (SMBR, three influent C/N ratios of 5, 10, and 20) was approximately completed in 32 days, shorter than that (40 days) required in R2 (SMBR, influent C/N ratio of 20). Higher removal efficiencies of 76.4% for TN, 70.1% for COD, and 79.2% for NH3-N were obtained in R1 than in R2. The high-throughput sequencing results indicated that after 150 days of operation, the Shannon index of bacteria in R1 increased from 2.97 to 4.41 and the growth of Nakamurella, Ferruginibacter, and Rhodanobacter was promoted in the reactor, which indicated substantial microbial diversity in the biofilm. Therefore, gradually adjusting the influent C/N ratio could effectively enhance the nitrogen removal performance of denitrification microbial communities in SMBRs. This study offers a reliable approach for starting the SMBR-enhanced biological nutrient removal process in wastewater treatment plants by gradually adjusting the influent C/N ratio.

Background Leaf senescence occurs in an age-dependent manner, but the rate and timing of leaf senescence may be influenced by various biotic and abiotic factors. In the course of stress, the function, composition, and different components of photosynthetic apparatus occur to be synthesized homogeneously or degraded paradoxically due to different senescence-related processes. Nitrogen (N) deficiency is one of the critical environmental factors that induce leaf senescence, and its incidence may curtail leaf photosynthetic function and markedly alter the genetic information of plants that might result in low grain yield. However, the physiological and genetic mechanism underlying N deficiency regulates premature senescence, and flag leaf function, ROS homeostasis, and intercellular sugar concentration in rice during grain filling are not well understood. In this paper, Zhehui7954 an excellent indica restorer line (wildtype) and its corresponding mutant (psf) with the premature senescence of flag leaves were used to study the effect of different N supplies in the alteration of physiological and biochemical components of flag leaf organ and its functions during grain filling. Results The results showed that the psf mutant appeared to be more susceptible to the varying N supply levels than WT. For instance, the psf mutant showed considerably lower Pn, Chl a, Chl b, and Car contents than its WT. N deficiency (LN) decreased leaves photosynthetic activities, N metabolites, but significantly burst O2•−, H2O2, and relative conductivity (R1/R2) concentrations, which was consistent with the expression levels of senescence-associated genes. Sucrose, glucose, and C/N ratio concentrations increased with a decrease in N level, which was closely associated with N and non-structural carbohydrate translocation rates. Increases in POD activity were positively linked with the senescence-related enhancement of ROS generation under LN conditions, whereas, SOD, CAT, and APX activities showed opposite trends. High N (HN) supply significantly inhibits the transcripts of carbohydrate biosynthesis genes, while N assimilation gene transcripts gradually increased along with leaf senescence. The psf mutant had a relatively higher grain yield under HN treatment than LN, while WT had a higher grain yield under MN than HN and LN. Conclusions This work revealed that the C/N ratio and ROS undergo a gradual increase driven by interlinking positive feedback, providing a physiological framework connecting the participation of sugars and N assimilation in the regulation of leaf senescence. These results could be useful for achieving a higher yield of rice production by appropriate N supply and plant senescence regulation.

Herein, the responses of the operational performance of a membrane bioreactor (MBR) with a high ammonium-nitrogen (NH4+-N) load and microbial community structure to increasing carbon to nitrogen (C/N) ratios were studied. Variation in the influent C/N ratio did not affect the removal efficiencies of chemical oxygen demand (COD) and NH4+-N but gradually abated the ammonia oxidization activity of sludge. The concentration of the sludge in the reactor at the end of the process increased four-fold compared with that of the seed sludge, ensuring the stable removal of NH4+-N. The increasing influent COD concentration resulted in an elevated production of humic acids in soluble microbial product (SMP) and accelerated the rate of membrane fouling. High-throughput sequencing analysis showed that the C/N ratio had selective effects on the microbial community structure. In the genus level, Methyloversatilis, Subsaxibacter, and Pseudomonas were enriched during the operation. However, the relative abundance of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) involved in nitrification declined gradually and were decreased by 86.54 and 90.17%, respectively, with influent COD increasing from 0 to 2000 mg/L. The present study offers a more in-depth insight into the control strategy of the C/N ratio in the operation of an MBR with a high NH4+-N load.

The use of biomass as renewable energy source is of interest in reducing dependence on fossil fuels and associated impacts of climate change. Water hyacinth (WH), an invasive aquatic plant of environmental concern has large biomass that is available for biogas production. Co-digestion of this largely lignocellulose biomass with other substrates may correlate process parameters and improve biogas production. This study evaluated co-digestion of WH biomass with various mix proportions of ruminal slaughterhouse waste (RSW) at 24, 32 and 37°C in order to assess the optimum proportion and temperature. The rate of biomethanation increased with temperature from 0.23 at 24ºC to 0.75 and 0.96 at 32ºC and 37ºC, respectively, and similarly methane yield improved from 14 at 24ºC to 40 and 52 L/kg air dried water hyacinth at 32ºC and 37ºC respectively. A WH: RSW ratio of 30% showed optimum acclimatization and methane yield in a residence time of 60 days. The duration of the initial drop in pH that indicates hydrolysis stage decreased with increase in proportion of RSW, indicating faster hydrolysis and fermentation processes. Longer and stable latter alkaline pH zone suggested improved biomethanation and greater biogas production. Co-digestion with 30% RSW at 24ºC improved biogas yield by 75% from 8.05 to 14.09L/Kg biomass, methane component of biogas by 9% from 59 to 68% and reduced the retention time for substrate by 36%, suggesting synergy in co-digestion with respect to biogas quality. Changing the temperature from 24 to 32ºC increased the yield by 186% and reduced retention time by 73%. The results demonstrated synergy in co-digestion of the two substrates and the process dynamics that are useful in a possible process commercialization. ©2019. CBIORE-IJRED. All rights reserved

The processes of nitrogen (N) mineralization from organic amendments (OA) is important to provide mineral forms (NH4+ and NO3−) of N for plants. Assessment of N mineralization is usually done by using the C/N ratio of OAs but limits to the predicting capability of such indicator have been reported. Here, we propose a new definition of organic carbon (C) quality based on 13C-CPMAS NMR that provide a more accurate prediction of N mineralization. A mesocosm incubation experiment was carried out to assess the effects of ten OA types on soil N mineralization in three different soils. OAs were chemically characterized by C/N ratio and in solid state spectroscopy by 13C-CPMAS NMR. Nitrogen mineralization in terms of NH4+ and NO3− was monitored after 3, 10, 30, 100, and 300 days of incubation. N mineralization was fast for OAs with high C quality coupled with high N content (e.g., meat powder, fish meal and alfalfa litter), while the same process was slow for amendment with low C quality even with high N content (e.g. humus, alfalfa biochar). On the contrary, a rapid but short-term N immobilization was found for OAs with high C quality but low N content (e.g., glucose). OAs with low C quality and low N content (e.g., sawdust, cellulose, wood biochar and grass litter) showed a slow, but long-lasting N immobilization. We found that C/N ratio was unable to predict the N mineralization for OAs with low C quality. Considering 13C-CPMAS NMR spectral regions, the carbonyl C, and N-alkyl and methoxyl C regions had the most significant positive correlation with N mineralization, while the di-O-alkyl C and O-alkyl C were strongly associated with N immobilization. This study demonstrates that the biochemical quality of organic C defined by 13C-CPMAS NMR is capable of predicting N dynamic pattern better than C/N ratio.

In this study, the isotopic composition (δ13C and δ15N), total organic carbon content, total nitrogen content, and C/N ratios of suspended particulate organic matter (POM) in Zhanjiang Bay, which is a semi-enclosed bay with concentrated artificial activities in Southern China, were analyzed in order to investigate the seasonal variations in the principal POM sources in the monsoon region. In summer, the δ13C and δ15N values showed a weak correlation with the chlorophyll a (Chl a), suggesting that terrigenous sources were dominant. However, in winter, the particulate organic carbon and particulate nitrogen values were correlated with the Chl a in the middle bay and bay mouth. Moreover, the δ13C values showed a significant correlation with Chl a during the winter, indicating that the contribution of the in situ phytoplankton was relatively important and was affected by the monsoon in winter. Compared with the corresponding δ13C values, the δ15N values exhibited a complex spatial distribution. By using a Bayesian mixing model, in the upper bay, the source of POM was mainly from marine organic matter (49%) in summer, and almost an equilibrated contribution of all sources in winter. In the middle bay and bay mouth, the POM contribution mainly originated from marine organic matter (53%) during the winter. In contrast, the POM source was mainly soil organic matter (63%) in summer, suggesting that the POM was sourced from the runoff from the upstream basin. Our results suggest that the seasonal shifts of the source of POM should be taken into account when estimating C or N mass balance in the monsoon-controlled bay.

Aims Data on the decomposition of fine roots are scarce for the Mediterranean basin. This work aims to compare chemical traits, decomposition rate, and temperature sensitivity (Q10) for root and leaf litter of 43 Mediterranean species. Methods We carried out a two-years litterbag decomposition experiment using 43 fine roots litter and leaf litter types incubated in laboratory conditions at three different temperatures, i.e. 4 °C, 14 °C, and 24 °C. Litter was characterized for carbon (C), nitrogen (N), lignin and cellulose concentration, C/N, and lignin/N ratios. Results Fine root litter had lower N content but higher lignin concentration, lignin/N, and C/N ratios compared to leaf litter. The decay rate of fine root litter was slower than leaf litter. For both tissues, the decay rate was negatively associated with lignin concentration, lignin/N, and C/N ratios but positively with N concentration. Q10 was higher for fine root than leaf litter, with a positive correlation with lignin while negative with N concentration. Conclusions Our findings demonstrate a higher Q10 accompanied by a slower decomposition rate of fine root litter compared to leaf litter in Mediterranean ecosystems. These results must be considered in modeling organic C at the ecosystem scale.

Haloarchaea produce C50 carotenoids such as bacterioruberin, which are of biotechnological in-terest. This study aimed to analyze the effect of different environmental and nutritional conditions on the cellular growth and dynamics of carotenoids accumulation in Haloferax mediterranei. The maximum production of carotenoids (40 µg·mL−1) was obtained during the stationary phase of growth, probably due to nutrient-limiting conditions (one-step culture). By seven days of culture, 1 mL culture produced 22.4 mg of dry weight biomass containing 0.18 % (w/w) of carotenoids. On the other hand, carbon-deficient cultures (low C/N ratio) were observed to be optimum for C50 bacterioruberin production by Hfx. mediterranei, but negatively affected the growth of cells. Thus, a two-steps process was evaluated for optimum carotenoids yield. In the first step, a nutri-ent-repleted culture medium enabled the haloarchaea to produce biomass, while in the second step, the biomass was incubated under osmotic stress and in a carbon-deficient medium. Under the conditions used, the obtained biomass contained 0.27% (w/w) of carotenoids after seven days, which accounts for 58.49 µg·mL−1 of carotenoids for a culture with turbidity 14.0. This work was funded by a research grant from MINECO Spain (RTI2018-099860-B-I00) and the University of Alicante (VIGROB-309). We are also indebted to the Andalusian Government (research project BIO-214). ZM was assisted by a pre-doctoral grant from “Plan Propio de Investigación” of the University of Huelva, Spain. MG was awarded with a pre-doctoral fellowship from the Valencian Community Government (ACIF/2019/043).

Sunflower plants (Helianthus annuus L.) in a CO2-enriched atmosphere (eCO2) were used herein to examine the developmental and physiological effects of biofertilization with mycorrhizae (Rhizophagus irregularis). The eCO2 environment stimulated colonization using R. irregularis mycorrhizal fungi, as compared to plants grown under ambient CO2 conditions (aCO2). This colonization promotes plant growth due to an increased nutrient content (P, K, Mg, and B), which favors a greater synthesis of photosynthetic pigments. Biofertilized plants (M) under eCO2 conditions have a higher concentration of carbon compounds in their leaves, as compared to non-biofertilized eCO2 plants (NM). The biofertilization (M) of sunflowers with R. irregularis decreased the C/N ratio, as compared to the NM plants, decreasing the hydrogen peroxide content and increasing the antioxidant enzyme activity (catalase and APX). These results suggest that sunflower symbiosis with R. irregularis improves the absorption of N, while also decreasing the plant’s oxidative stress. It may be concluded that biofertilization with mycorrhizae (R. irregularis) may potentially replace the chemical fertilization of sunflower plants (H. annuus L.), resulting in more environmentally friendly agricultural practices. This information is essential to our understanding of the mechanisms influencing the C and N dynamic in future climate change scenarios, in which high CO2 levels are expected.

Fil: Aguilara, Lorena. Universitat Politécnica de Catalunya; España Fil: Aguilara, Lorena. UNESCO Chair on Sustainability; Francia Fil: Gallegos, Ángel. UNESCO Chair on Sustainability; Francia Fil: Gallegos, Ángel. Universitat Politécnica de Catalunya; España Fil: Pérez, Leonardo Martín. Pontificia Universidad Católica Argentina. Facultad de Química e Ingeniería del Rosario. Instituto de Investigaciones en Ingeniería Ambiental, Química y Biotecnología Aplicada; Argentina Fil: Pérez, Leonardo Martín. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentinas Fil: Pérez, Leonardo Martín. Politécnica ecnica de Catalunya; España Fil: Pérez, Leonardo Martín. NESCO Chair on Sustainability; Francia Fil: Arias, Carlos A. University of Aarhus. Department of Biological Sciences; Dinamarca Fil: Arias, Carlos A. Aarhus University. Centre for Water Technology; Dinamarca Fil: Rubio, Raquel. Universitat Politécnica de Catalunya; España Fil: Rubio, Raquel. UNESCO Chair on Sustainability; Francia Fil: Haulani, Leila. Universitat Politécnica de Catalunya; España Fil: Haulani, Leila. UNESCO Chair on Sustainability; Francia Fil: Garciá Raurich, Josep. Universitat Politécnica de Catalunya. Centro de Investigación en Seguridad y Control Alimentario; España Fil: Pallarés, Marc. Grupo de Desarrollo Empresarial; España Fil: de Pablo, Joan. Universitat Politécnica de Catalunya. Resource Recovery and Environmental Management; España Fil: Morató, Jordi. Universitat Politécnica de Catalunya; España Fil: Morató, Jordi. UNESCO Chair on Sustainability; Francia Abstract: In this work, we have evaluated the impact of intermittent induced aeration in total nitrogen (TN), ammonia (NH4-N) and nitrate-nitrogen (NO3-N) removal in four pilot-scale vertical flow constructed wetlands (VFCW) (two aerated two non-aerated) using cork by-product or gravel as the filter material and planted with Phragmites australis. Both aerated and non-aerated systems achieved high COD and BOD5 elimination rates ( 90%) at the end of the 5-month test period. However, the aerated systems presented maximal COD and BOD5 removal from the third month of operation onwards since air supply favored the oxidative bioprocesses occurring within the wetlands. Cork and gravel aerated VFCW also proved to be more efficient (p

Aims: Data about woody debris (WD) decomposition are very scarce for the Mediterranean basin. The specific aim of this work is to explore the relationships between WD traits with the decay rate. Methods: We carried out a three-year litterbag decomposition experiment using ten WD types incubated in two plant communities (i.e. shrubland and woodland) and in laboratory conditions. WD was characterized for 31 chemical and anatomical traits, including macro- and micronutrients, lignin, and cellulose as well as organic chemistry by Solid-state Cross-Polarization Magic Angle Spinning Carbon-13 Nuclear Magnetic Resonance (13C CPMAS NMR) and Fourier transform infrared spectroscopy/ Attenuated Total Reflection (FT-IR/ATR spectroscopy). Results: WD decay rate was negatively associated with di-O-alkyl, lignin/N and C/N ratios, but positively with N concentration. Less consistent but positive correlations were recored for K, Mn, and Na concentration. The alkyl C and carboxylic C regions, associated with aliphatic and amide compounds, was positively correlated with WD decomposition. Conversely, di-O-alkyl C and O-alkyl C fractions, largely associated with cellulose and hemicellulose, were negatively correlated with WD decay rate. Finally, the positive correlation between Na concentration and WD mass loss in field conditions suggest a role of this neglected micronutrient for wood decomposition. WD specific density and anatomical features, have a minor capability to explain decomposition rate. Conclusions: Our findings demonstrate a major role of WD chemical traits in explaining the variability of decomposition in Mediterranean ecosystems.

It is well established that an optimal aerobic and anaerobic microbial metabolism is achieved with a C/N ratio between 20 and 30. Most studies are currently based on chemically-measured carbon and nitrogen contents. However, some organic wastes can be composed of recalcitrant carbon fractions that are not bioavailable. To know the biodegradable C/N ratio, two different methods to determine the aerobic and anaerobic biodegradable organic carbon (BOC AE [subíndex] and BOC AN [subíndex]) are proposed and used to analyze a wide variety of different organic samples. In general, raw wastes and digested products have more amount of BOCAE. On the contrast, the samples collected after an aerobic treatment have higher content of BOC AN [subíndex]. In any case, all the BOC fractions are lower than the total organic carbon (TOC). Therefore, the C/N ratios based on BOC are always lower than the total C/N ratio based on the TOC measure. The knowledge of the real bioavailable C/N ratio is crucial for the biological treatments of organic materials. To reduce the test time necessary for BOC determination, the values of BOC for all the samples obtained at different times were compared and correlated with the final BOC. A method that allows for the determination of BOC AE [subíndex] in 4 d is proposed. In relation to the anaerobic assay, the biogas potential calculated after 21 and 50 d was positively correlated with the final potential defined after 100 d of assay.

Background Heterotrophic cultivation of microalgae has been proposed as a viable alternative method for novel high-value biomolecules, enriched biomass, and biofuel production because of their allowance of high cell density levels, as well as simple production technology. Tetradesmus bernardii, a newly isolated high-yielding oleaginous microalga under photoautotrophic conditions, is able to grow heterotrophically, meaning that it can consume organic carbon sources in dark condition. We investigated the effect of different carbon/nitrogen (C/N) ratios on the growth and lipid accumulation of T. bernardii in heterotrophic batch culture under two nitrogen sources (NaNO3 and CO(NH2)2). In addition, we conducted time-resolved transcriptome analysis to reveal the metabolic mechanism of T. bernardii in heterotrophic culture. Results T. bernardii can accumulate high biomass concentrations in heterotrophic batch culture where the highest biomass of 46.09 g/L was achieved at 100 g/L glucose concentration. The rate of glucose to biomass exceeded 55% when the glucose concentration was less than 80 g/L, and the C/N ratio was 44 at urea treatment. The culture was beneficial to lipid accumulation at a C/N ratio between 110 and 130. NaNO3 used as a nitrogen source enhanced the lipid content more than urea, and the highest lipid content was 45% of dry weight. We performed RNA-seq to analyze the time-resolved transcriptome of T. bernardii. As the nitrogen was consumed in the medium, nitrogen metabolism-related genes were significantly up-regulated to speed up the N metabolic cycle. As chloroplasts were destroyed in the dark, the metabolism of cells was transferred from chloroplasts to cytoplasm. However, storage of carbohydrate in chloroplast remained active, mainly the synthesis of starch, and the precursor of starch synthesis in heterotrophic culture may largely come from the absorption of organic carbon source (glucose). With regard to lipid metabolism, the related genes of fatty acid synthesis in low nitrogen concentration increased gradually with the extension of cultivation time. Conclusion T. bernardii exhibited rapid growth and high lipid accumulation in heterotrophic culture. It may be a potential candidate for biomass and biofuel production. Transcriptome analysis showed that multilevel regulation ensured the conversion from carbon to the synthesis of carbohydrate and lipid.

A sequencing batch reactor (SBR) with an intermittent aeration mode was established to achieve partial nitrification (PN) and the short-term effects of C/N ratios were investigated. Stable nitrite accumulation was achieved after 107 cycles, about 56d, with the average ammonia nitrogen removal efficiency (ARE) and nitrite accumulation rate (NAR) of 96.92% and 82.49%, respectively. When the C/N ratios decreased from 4.64 to 3.87 and 2.32, ARE and NAR still kept a stable and high level. However, when the C/N ratio further decreased to 0.77, nitrite accumulation became fluctuation, and ARE, total nitrogen (TN), and chemical oxygen demand (COD) removal performance declined obviously. Except for four common phyla (Proteobacteria, Bacteroidetes, Chloroflexi, and Acidobacteria) in the wastewater treatment system, Patescibacteria, the newly defined superphylum, was found and became the most dominant phylum in the PN sludge for their ultra-small cell size. The only ammonia oxidation bacteria (AOB), Nitrosomonas, and nitrite oxidation bacteria (NOB), Nitrospira, were detected. The relative abundance of NOB was low at different C/N ratios, showing the stable and effective inhibition effects of intermittent aeration on NOB growth.

Cyanotoxins are the underlying cause of the threat that globally pervasive Cyanobacteria Harmful algal blooms (CyanoHABs) pose to humans. Major attention has been focused on the cyanobacterial hepatotoxin microcystins (MCs), however, there is a dearth of studies on cyanobacterial neurotoxin anatoxins. In this study, we explored how an anatoxin-producing Cuspidothrix issatschenkoi strain responded to culture with inorganic and organic nitrogen sources in terms of growth and anatoxins production. The results of our study revealed that ʟ- alanine could greatly boost cell growth, and was associated with the highest cell productivity, while urea significantly stimulated anatoxin production with the maximum anatoxin yield reaching 25.86 &mu, g/mg dry weight, which was 1.56-fold higher than that in the control group (BG11). To further understand whether the carbon/nitrogen balance in C. issatschenkoi would affect anatoxin production, we explored growth and toxin production in response to different carbon/nitrogen ratios (C/N). Anatoxin production was mildly promoted when the C/N ratio was within low range, and significantly inhibited when the C/N ratio was within high range, showing approximately a three-fold difference. Furthermore, the transcriptional profile revealed that anaC gene expression was significantly up-regulated over 2&ndash, 24 h when the C/N ratio was increased, and was significantly down-regulated after 96 h. Overall, our results further enriched the evidence that urea can stimulate cyanotoxin production, and ʟ-alanine could boost C. issatschenkoi proliferation, thus providing information for better management of aquatic systems. Moreover, by focusing on the intracellular C/N metabolic balance, this study explained the anatoxin production dynamics in C. issatschenkoi in response to different N sources.

In order to quantify the reduction potential for nitrous oxide (N2O) release from arable soils through the removal of crop residues, we conducted an experiment after sugar beet (Beta vulgaris L.) harvest with three treatments: (i) ploughing of the crop residues (+CR:D), (ii) returning residues after ploughing on the surface (+CR:S), and (iii) removal of the residues and ploughing (&minus, CR). N2O fluxes were measured over 120 days in south Germany. High positive correlations between N2O fluxes and the CO2 fluxes and soil nitrate contents suggested denitrification as the main N2O source. N2O emissions in +CR:D was higher than in +CR:S (2.39 versus 0.93 kg N2O&minus, N ha&minus, 1 120 d&minus, 1 in +CR:D and +CR:S). Residue removal in &minus, CR reduced the N2O emission compared to +CR:D by 95% and to +CR:S by 87%. We further conducted a meta-analysis on the effect of crop residue removal on N2O emissions, where we included 176 datasets from arable soils with mainly rain fed crops. The overall effect of residue removal showed a N2O reduction of 11%. The highest N2O reduction of 74% was calculated for the removal subgroup with C/N-ratio &lt, 25. Neither the remaining C/N-ratio subgroups nor the grouping variables &ldquo, tillage&rdquo, or &ldquo, residue quantity&rdquo, differed within their subgroup.

Soils originating from the Caiuá sandstone formation have low soil organic matter (SOM), clay content, and cation exchange capacity (CEC). The predominance of one component over the other might decisively influence the CEC of these soils. Particle size distribution and selective dissolution procedures associated to a suit of methods to determine the exchangeable capacity properties might clarify the relative importance of each soil component. The objective of this work was to evaluate the contribution of the different components of the solid fraction and their intrinsic attributes to the CEC of sandy-loam soils and their relation to the total organic carbon (TOC), C:N ratio, and soil mineralogy. For this purpose, 34 soil samples were selected from the Caiuá sandstone formation with significant variation in the carbon content. Clay size fraction was characterized by X-ray diffraction, routine chemical analysis, and total specific surface area-SSA T using EGME, before and after the removal of SOM with sodium hypochlorite solution. Different values of CEC and effective cation exchange capacity (ECEC) were determined following standard procedures. The soils presented high sand content (82.9 ± 5.9 %) and the mineralogy of the clay fraction is dominated by kaolinite (>80 %) with the presence of illite, 2:1 clay minerals, and small amounts of iron and aluminum oxides. The CEC and ECEC values at pH 7.0 and ~5.6, respectively due to the SOM are 408.6 and 148.7 cmol c kg -1 of carbon, respectively. The SOM was responsible for 32 to 84 % (average 52 %) and 24 to 67 % (average of 46 %) of the CEC and ECEC of the soils, respectively. The CEC and ECEC of the inorganic fraction are 2.32 and 0.78 cmol c kg -1 of minerals, respectively. The CEC of the clay fraction increased with the TOC but decreased exponentially with the clay content. The total carbon content increased linearly with the C/N ratio. The SSA T showed a significant (p

In this study, the effect of aerobic denitrification on nitrogen removal was investigated using two zero-discharge biofloc-based recirculating aquaculture systems with representative carbon-to-nitrogen (C/N) ratios of 15 (CN15) and 20 (CN20). Aquaculture wastewater, residual feed, and fish feces were treated in an aerated suspended growth reactor (SGR, dissolved oxygen > 5.0 mg L–1). Low toxic NH3 (

Wheat is an important staple food crop of the world and it accounts for 18–20% of human dietary protein. Recent reports suggest that CO2 elevation (CE) reduces grain protein and micronutrient content. In our earlier study, it was found that the enhanced production of nitric oxide (NO) and the concomitant decrease in transcript abundance as well as activity of nitrate reductase (NR) and high affinity nitrate transporters (HATS) resulted in CE-mediated decrease in N metabolites in wheat seedlings. In the current study, two bread wheat genotypes Gluyas Early and B.T. Schomburgk differing in nitrate uptake and assimilation properties were evaluated for their response to CE. To understand the impact of low (LN), optimal (ON) and high (HN) nitrogen supply on plant growth, phenology, N and C metabolism, ROS and RNS signaling and yield, plants were evaluated under short term (hydroponics experiment) and long term (pot experiment) CE. CE improved growth, altered N assimilation, C/N ratio, N use efficiency (NUE) in B.T. Schomburgk. In general, CE decreased shoot N concentration and grain protein concentration in wheat irrespective of N supply. CE accelerated phenology and resulted in early flowering of both the wheat genotypes. Plants grown under CE showed higher levels of nitrosothiol and ROS, mainly under optimal and high nitrogen supply. Photorespiratory ammonia assimilating genes were down regulated by CE, whereas, expression of nitrate transporter/NPF genes were differentially regulated between genotypes by CE under different N availability. The response to CE was dependent on N supply as well as genotype. Hence, N fertilizer recommendation needs to be revised based on these variables for improving plant responses to N fertilization under a future CE scenario.

Litter mass loss and nutrient release are key links in the material cycling and energy flowing in ecosystems and of special ecological significance in maintaining ecosystem stability, improving soil structure and promoting vegetation restoration in the arid and semi-arid regions. Furthermore, litter mass loss could be affected by the change in precipitation patterns. However, currently, most studies on the response of litter mass loss to precipitation pattern change focus on the precipitation amount much more than the precipitation frequency. Therefore, we conducted a three-year manipulative research in a desert steppe to assess the effects of decreasing precipitation amount and increasing precipitation interval on the litter mass loss of Stipa klemenzii, and their relationships with litter chemical traits (contents of carbon (C), nitrogen (N), phosphorus (P), potassium (K), lignin and ash, C/N ratio and lignin/N ratio) and abiotic factors (light intensity and temperature and humidity of soil and air). The results showed that (1) both the treatments have negative effects on litter mass loss; (2) for abiotic factors, both the treatments only affected soil moisture; for biotic factors, both the treatments decreased the litter lignin contents, the increased precipitation interval treatment decreased the litter N and K contents while increased the litter C/N ratio and lignin/N ratio; (3) the main control of litter mass loss was due to our manipulation of drought regime and its effects on the soil decomposition environment, rather to other factors such as litter quality or light intensity; (4) compare to decreased precipitation amount, increased precipitation interval has more impact on litter mass loss, and this was caused by the increased litter C/N ratio in increased precipitation interval treatment. We speculated that increased precipitation interval was a harsher abiotic factor for the decomposer, and more research on this should be conducted in the future.

Elucidating the mineralization of organic composts makes it possible to understand the release of nutrients to plants. The objective of this study was to evaluate the mineralization of nitrogen (N) and carbon (C) from organic compost from residues of the production and slaughter of small ruminants, applied on a Neossolo Flúvico (Fluvents). The compost consists of remains of grass (forage), manure and slaughter residues such as blood, viscera and the carcass of goats and sheep. Under laboratory conditions, two experiments were conducted in a completely randomized design, considering the doses of organic compost at the following levels: zero; 3.75, 7.5, 15 and 30 Mg ha-1. For the N and C mineralization tests, 11 and 32 collection times (sampling periods) were evaluated, respectively. Inorganic N content (ammonium and nitrate) was measured in the N mineralization test, and CO2-C concentration was quantified in the C mineralization test. The largest increments between the applied doses of organic compost from residues of the production and slaughter of small ruminants were 70% and 69% for potentially mineralizable N and C, with amounts of 7.5 and 30 Mg ha-1 at doses of 3.75 and 7.5 Mg ha-1, respectively. Organic C and N from residues of the production and slaughter of small ruminants are rapidly mineralized in the soil (up to 45 days) due to their low C/N ratio. A elucidação do processo de mineralização de compostos orgânicos permite entender a liberação de nutrientes para as plantas. Objetivou-se com este trabalho avaliar a mineralização de nitrogênio e carbono de composto orgânico proveniente de resíduos da produção e abate de pequenos ruminantes, aplicados sobre um Neossolo Flúvico. O composto consiste de restos de capim (forrageiras), estercos e resíduos do abate como sangue, vísceras e a carcaça de caprinos e ovinos. Em condições de laboratório, dois experimentos foram conduzidos em um delineamento inteiramente casualizado, considerando-se as doses de composto orgânico nos seguintes níveis: zero; 3,75; 7,5; 15 e 30 Mg ha-1. Para o ensaio de mineralização de nitrogênio e carbono foram avaliados 11 e 32 tempos de coletas (épocas de amostragem), respectivamente. No ensaio de mineralização de nitrogênio foi medido o teor de nitrogênio inorgânico (amônio e nitrato) e no experimento de carbono foi quantificado a concentração de C-CO2. O maior incremento entre as doses aplicadas de composto orgânico proveniente de resíduos da produção e abate de pequenos ruminantes foi de 70% e 69% para o nitrogênio e o carbono potencialmente mineralizável com as quantidades de 7,5 e 30 Mg ha-1, em relação as doses de 3,75 e 7,5 Mg ha-1, respectivamente. O carbono e o nitrogênio orgânico provenientes com composto de resíduos da produção e do abate de pequenos ruminantes são rapidamente mineralizados no solo (até 45 dias) devido à sua baixa relação C/N. &nbsp

Increasing the C/N ratio of input feed has been reported as a practical approach for improving water quality and enhancing shrimp growth through changing the bacterial community of rearing water. However, little is known about the effects of different C/N ratios of feed input on the intestinal microbiota and metabolome of shrimp. In the present study, the effects of three different C/N ratio levels (CN6, CN10, and CN15) maintained by adding sucrose on the growth, intestinal microbiota and metabolome of Litopenaeus vannamei, and bioflocs formation were investigated after 17 days of feeding. The results indicated that higher C/N ratio (10 and 15), especially CN15, of feed input significantly enhance the length and weight of shrimp individuals accompanied by a significant accumulation of bioflocs, compared to that of CN6. The increase of C/N ratio input decreased the α-diversity of the intestinal microbiota and changed the microbial community structure through increasing the relative abundance of Actinobacteria, Rhodobacteraceae (mainly consist of Roseobacter and Paracoccus groups), Alteromonadaceae, and inhibiting the growth of Cyanobacteria, certain Rhodobacteraceae, Mycoplasmataceae and Vibrio. The change of microbial community caused by increasing C/N ratio input was closely associated with various bioactive metabolites of flavonoids, benzenoids, prenol lipids, and indole derivatives, which are benefit for shrimp growth either as an antimicrobial agent or as a nutrient component. Overall, this study demonstrated that manipulating high C/N ratio of feed input helps to the growth of shrimp through increasing the relative abundance of potential beneficial bacteria and the accumulation of various bioactive metabolites to suppress the growth of detrimental bacteria.

The input of land use specific organic matter into lowland streams may impact sediment characteristics in terms of food resources and habitat structure, resulting in differences in macroinvertebrate community composition. Therefore, we investigated to what extent land use specific sediment food and habitat characteristics structure macroinvertebrate communities. To this purpose linear multiple regression models were constructed, in which macroinvertebrate biotic indices were considered as response variables and sediment characteristics as predictor variables, analysed in 20 stream stretches running through five different land use types. Sediment characteristics and macroinvertebrate community composition were land use specific. The carbon/nitrogen (C/N) ratio, woody debris substrate cover and the origin of fatty acids influenced macroinvertebrate community composition. Shannon-Wiener diversity was better explained by fatty acids origin, such as in grassland streams, where a higher relative content of plant derived fatty acids related to a higher macroinvertebrate diversity. In cropland and wastewater treatment plant (WWTP) streams with a low C/N ratio and dominated by microbial derived fatty acids, higher abundances of Oligochaeta and Chironomus sp. were observed. Ephemeroptera, Plecoptera, and Trichoptera (EPT) richness was positively related to woody debris substrate cover, which only occurred in forest streams. Hence, macroinvertebrate community composition was influenced by the origin of the organic material, being either allochthonous or autochthonous and when autochthonous being either autotrophic or heterotrophic. It is therefore concluded that sediment food and habitat characteristics are key ecological filters.

Sugar beet crown and root rot caused by Rhizoctonia solani is a major yield constraint. Root rot is highly increased when R. solani and Leuconostoc mesenteroides co-infect roots. We hypothesized that the absence of plant cell-wall-degrading enzymes in L. mesenteroides and their supply by R. solani during close contact, causes increased damage. In planta root inoculation with or without cell-wall-degrading enzymes showed greater rot when L. mesenteroides was combined with cellulase (22 mm rot), polygalacturonase (47 mm), and pectin lyase (57 mm) versus these enzymes (0–26 mm), R. solani (20 mm), and L. mesenteroides (13 mm) individually. Carbohydrate analysis revealed increased simpler carbohydrates (namely glucose + galactose, and fructose) in the infected roots versus mock control, possibly due to the degradation of complex cell wall carbohydrates. Expression of R. solani cellulase, polygalacturonase, and pectin lyase genes during root infection corroborated well with the enzyme data. Global mRNAseq analysis identified candidate genes and highly co-expressed gene modules in all three organisms that might be critical in host plant defense and pathogenesis. Targeting R. solani cell-wall-degrading enzymes in the future could be an effective strategy to mitigate root damage during its interaction with L. mesenteroides.

Predicting N mineralization from green manure in different soil types during the cold season is instrumental for improving crop management with higher N use efficiency and reduced risks of N losses in a cool and humid climate. The objective of our work was to study the effects of low temperatures and soil type on the net nitrogen (N) mineralization and the relationship between N and carbon (C) mineralization from N-rich plant material. A silty clay loam and a sandy loam were incubated with or without clover leaves for 80 days at 0, 4, 8.5 or 15 °C. The results showed a substantial mineralization of N in clover leaves (7% of N added), unaffected by temperature, already on 3rd day. This was followed by net N immobilization for about 4 weeks in the clay soil, with similar tendencies in the sandy soil, and more severely at the higher than the lower temperatures. After 80 days of incubation, net N mineralization was only 13–22% of total N in clover leaves. The ratio of net mineralized N to C was higher at lower temperatures, and higher in the sandy than in the clay soil. After the immobilization period, the N mineralization increased, positively related to temperature, and the ratio of net mineralized N to C became constant. In conclusion, low temperature during the initial phase of mineralization altered the ratio between net N and C mineralization from easily decomposable plant material, and the net N mineralization occurred more rapidly in the sandy soil. The change in stoichiometry at low temperatures, as well as the modifying effect of soil type, should be considered when predicting N mineralization of N-rich plant material.

The composting of sewage sludge and maize straw mixtures was investigated in this study. The aim was to analyze the influence of different proportions of sewage sludge and maize straw in the mixtures on composting process dynamics (expressed by heat production) and gas emissions. The results showed that all examined mixtures reached a strong thermophilic phase of composting; however, the lowest dynamic of temperature growth was observed in the case of the biggest sewage sludge content (60% of sewage sludge in the composting mixture). The ammonia concentration inside bioreactor chambers was directly related to the content of sewage sludge in the composted mixture. Excessive contents of sewage sludge had a considerable effect on very low C/N ratios and high losses through ammonia emissions. Tests were carried out in reactors with a capacity of 160 dm3 under controlled conditions. All mixtures were aerated by the average air-flow of about 2.5 dm3∙min−1, i.e., the minimum air-flow that allows a temperature of about 70 °C to be reached and a sufficiently long thermophilic phase, which ensures proper composting.

Reductive soil disinfestation (RSD) has recently attracted much attention owing to its effectiveness for controlling pathogens. In this study, we aimed to evaluate the effects of different C/N substrates on RSD and to explore the changes in microbial community structure during RSD treatment. The experimental set up included 10 groups, as follows: CK, without substrates; RSD treatments with alfalfa (Medicago sativa L.)[AL], maize (Zea mays Linn. Sp.) straw [MS], and rice (Oryza sativa L.) straw [RS], with three levels of addition (0.5% [L], 2% [M], and 5% [H]), yielding ALL, ALM, ALH, MSL, MSM, MSH, RSL, RSM, and RSH groups. Compared with CK, RSD treatments significantly increased the content of NH4+-N, and effectively eliminated the accumulated NO3--N in the soil. The relative abundances of organic acid producers, including Clostridium, Coprococcus, and Oxobacter, in all RSD groups were significantly higher than those in the CK by day 21. Moreover, on day 21, Aspergillus and Fusarium in all RSD groups were significantly lower than those in the CK. In summary, RSD treatments clearly increased the relative abundances of organic acid generators and effectively inhibited pathogens; however, when the C/N was too low and the amount of addition too high, ammonia poisoning and rapid growth of some microorganisms (e.g., Pseudallescheria and Arthrographis) may occur.

Weed residues can influence nutrient cycling in agroecosystems. Quantifying this potential nutrient source may influence weed control and fertilisation practices. Nicandra physalodes (L.) Gaertn. is a weed with a short life cycle and a great ability to accumulate dry matter. Field observations suggest that N. physaloides residues are easily decomposed in soil. The objective of this study was to evaluate the effect of increasing of N, P and K doses on the growth of N. physalodes, as well as the nutrient content, chemical characteristics and C/N ratio of the weed. A randomised block design, arranged in split-plot with three replications, was utilised. The main plots were given four doses of NPK (Dose 1 - 0, 0.3 and 17.2 mg dm-3; Dose 2 - 30, 450.3 and 75.4 mg dm-3; Dose 3 - 60, 900.3 and 133.4 mg dm-3; and Dose 4 - 120, 1800.3 and 249.68 mg dm-3), and the subplots were harvested at ten time points after emergence (26, 33, 40, 47, 54, 61, 76, 91, 106 and 121 days). Higher dry matter production and N, P and K content were observed in plants grown on higher levels of fertiliser. The increase of N, P and K levels in the soil resulted in greater total accumulation of these macronutrients. The highest macronutrient contents were K and N. The treatments did not affect neutral detergent fibre (NDF), acid detergent fibre (ADF) and C/N ratio of plant. N. physalodes had low C/N ratio, low NDF and ADF levels, and great nutrient accumulation, suggesting that this plant is quickly decomposed, providing a rapid cycling of nutrients. RESUMO Os resíduos de plantas daninhas são importantes para a ciclagem de nutrientes nos agroecossistemas. A quantificação desta potencial fonte de nutrientes pode influenciar o manejo dessas plantas e as práticas de adubação. Nicandra physalodes (L.) Gaertn. (joá-de-capote) é uma planta daninha de ciclo curto com rápido crescimento e grande capacidade de acumular biomassa. Dessa forma, objetivou-se conhecer o potencial de acúmulo e ciclagem de nutrientes de N. physalodes e avaliar se o aumento de nitrogênio (N), fósforo (P) e potássio (K) no solo influenciam essas características. Utilizou-se delineamento de blocos casualizados, arranjado em parcelas subdivididas com três repetições. As parcelas foram constituídas de quatro doses crescente de N, P e K (Dose 1 - 0, 0,3 e 17,2; Dose 2 - 30, 450,3 e 75,4; Dose 3 - 60, 900,3 e 133,4 e Dose 4 - 120, 1800,3 e 249,68 mg dm-3) e as subparcelas de dez épocas de coleta das plantas (26, 33, 40, 47, 54, 61, 76, 91, 106 e 121 dias após emergência). O aumento nos níveis de N, P e K no solo proporcionou maiores produções de massa seca e acúmulo total desses macronutrientes em plantas de N. physalodes, sendo que os maiores acúmulos foram de K e N. A adubação não influenciou os teores de fibra em detergente neutro (FDN), fibra em detergente ácido (FDA) e a relação carbono/ nitrogênio da planta. N. physalodes apresenta baixa relação C/N, o que aliado aos baixos teores de FDN e FDA e ao bom acúmulo de nutrientes, sugere que o material vegetal dessa planta seja rapidamente decomposto, proporcionando uma ciclagem rápida de nutrientes no solo.

Purpose The objective of research was emphasized on the optimal conditions (initial pH and C/N ratio) for enhancing bioenergy from food waste by a two-stage fermentation process. Methods Bioenergy production from food waste was operated by mixed culture under thermophilic temperature in batch reactor. Thermophilic biohydrogen production was optimized in terms of initial pH (5.0–9.0) and then was optimized in terms of C/N ratio (10–50) in the first stage. After that, thermophilic biomethane production was optimized in terms of initial pH (6.0–10.0) in the second stage. Results The results revealed that the thermophilic biohydrogen production from food waste at an initial pH 7.0 presented the maximum hydrogen yield of 176.10 mL H2/g COD. At this optimal initial pH, the maximum hydrogen yield of 214.88 mL H2/g COD was achieved at C/N ratio 30. Subsequently, the effluent from the first stage of thermophilic biohydrogen production from food waste under the optimal initial pH of 7.0 and the optimal C/N ratio of 30 was used as a substrate in the second stage of thermophilic biomethane production. Thermophilic biomethane production from hydrogen fermentation effluent provided the maximum methane yield of 310.77 mL CH4/g COD at initial pH 7.0. At these optimal conditions, COD removal was achieved at 70–90%. Conclusion Therefore, a two-stage thermophilic fermentation process could effectively enhance biohydrogen and biomethane production, including reduction of organic waste at the same time.

Biochars have been proposed for remediation of metal-contaminated water due to their low cost, high surface area and high sorption capacity for metals. However, there is a lack of understanding over how feedstock material and pyrolysis conditions contribute to the metal sorption capacity of biochar. We produced biochars from 10 different organic materials by pyrolysing at 450 °C and a further 10 biochars from cedar wood by pyrolysing at 50 °C intervals (250–700 °C). Batch sorption experiments were conducted to derive the maximum Cu and Zn sorption capacity of each biochar. The results revealed an exponential relationship between Cu and Zn sorption capacity and the feedstock C/N ratio and a sigmoidal relationship between the pyrolysis temperature and the maximum Cu and Zn sorption capacity. FTIR analysis revealed that as temperature increased, the abundance of functional groups reduced. We conclude that the high sorption capacity of high temperature biochars is due to an electrostatic attraction between positively charged Cu and Zn ions and delocalised pi-electrons on the greater surface area of these biochars. These findings demonstrate a method for predicting the maximum sorption capacity of a biochar based on the feedstock C/N ratio and the pyrolysis temperature. Electronic supplementary material The online version of this article (10.1007/s11356-017-1047-2) contains supplementary material, which is available to authorized users.

This work evaluated the feasibility of glycerol as the sole carbon source for nutrient biological removal in an intermittently aerated bioreactor. The reactor operation was divided into two phases: the first one aimed only at removing nitrogen; and the second one aimed at removing nitrogen and phosphorus. In the first operational phase, three C/N (Carbon / Nitrogen) ratios were tested: 1.2, 1.5 and 1.8. For a C/N ratio of 1.8, higher denitrification efficiency was achieved (91 ± 8%). During the second phase, the reactor was subjected to periods of aeration and non-aeration of 2 h and 4 h, respectively, for a C/P (Carbon / Phosphorus) ratio of 10. The biological phosphorus removal in this phase was not significant (12 ± 9%), indicating that there was no development of PAO (Phosphorus Accumulating Organisms), since phosphate release did not occur during the anaerobic phase. This can be explained by the lack of VFA (Volatile Fatty Acids), which should come from the anaerobic degradation of the remaining amount of glycerol after denitrification was completed. The optical microscopy analysis indicated the presence of filamentous bacteria similar to the genusBeggiatoa, which could also have consumed part of the substrates from the glycerol fermentation.

Background: Surfactant is one of the most important raw materials used in various industrial fields, such as emulsifiers, corrosion inhibitors, foaming agent and detergent products. However, the commercial surfactant production is still costly and its demand is steadily increasing. This study aims to evaluate the performance of typical strains of Bacillus sp. to produce biosurfactants through a fermentation process. It also included the investigation of effect of initial glucose concentration and the ratio of carbon to nitrogen. Results: The biosurfactant was produced in the range of 1-2.46 g/L at initial glucose concentrations of 10-70 g/L. The optimum condition was achieved at a carbon to nitrogen ratio of 12.4 with the decrease in surface tension up to 27 mN/m. Conclusions: For further development and industrial applications, the modified Gompertz equation was proposed to predict the cell mass and biosurfactant production as the goodness of fitting was obtained. The modified Gompertz equation was also extended to enable the excellent prediction of the surface tension. Normal 0 false false false EN-US X-NONE AR-SA /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Tabla normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman",serif; mso-ansi-language:EN-GB; mso-fareast-language:EN-GB;}