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Numerous onshore oil production wells currently exist, and the petroleum hydrocarbon contamination of the surrounding soil caused by oil production wells is not well understood. Moreover, the impact of the distribution of the total petroleum hydrocarbons (TPH) in the soil on the microbiota requires further investigation. Accordingly, in this study, the distribution of petroleum hydrocarbons in the soils around oil production wells was investigated, and their alteration of the microbiota was revealed. The results revealed that in the horizontal direction, the heavily TPH-contaminated soils were mainly distributed within a circle with a radius of 200 cm centered on the oil production well; and in the vertical direction, the heavily TPH-contaminated soils were distributed within the 0–50 cm soil layer. A significant positive correlation was found between the microbial abundance and the TPH concentration in the soil with relatively low total carbon contents. Heavy TPH contamination (TPH concentration of >3000 mg/kg) significantly reduced the microbial diversity and altered the microbiota compared with the light TPH contamination (TPH concentration of around 1000 mg/kg). In the heavily TPH-contaminated soils, the relative abundances of the Proteobacteria and Bacteroides increased significantly; the network complexity among the soil microorganisms decreased; and the co-occurrence patterns were altered. In summary, the results of this study have reference value in the remediation of soils around oil production wells and provide guidance for the construction of microbial remediation systems for petroleum contamination. [Display omitted] • Soils in the immediate vicinity of the oil wells is heavily contaminated with TPH. • Microbial abundance in soils is significantly and positively correlated with TPH. • Heavy petroleum contamination reduces microbial α diversity and alters β diversity. • High petroleum hydrocarbons concentrations reduce microbial interactions in soils. [ABSTRACT FROM AUTHOR]

Detection of N -acyl homoserine lactones (AHLs) is useful for understanding quorum sensing (QS) behaviors, including biofilm formation, virulence and metabolism. For detecting AHLs and indicating the host cells in situ, we constructed the plasmid pUCGMA2T 1–4 to make a dual fluorescent whole-cell biosensor based on the AhlI/R AHL system of Pseudomonas syringae pv. syringae B728a. The plasmid contains three components: constitutively expressed P nptII :: gfp for indicating host cells, P ahlI :: mcherry that produces red fluorescence in response to AHL, and the ahlR gene that encodes an AHL regulatory protein. Meanwhile, two copies of T 1–4 (four tandem copies of a transcriptional terminator) were added into the plasmid to reduce background. The results showed that when the plasmid was placed into Escherichia coli, the dual fluorescence whole-cell biosensor was able to respond with red fluorescence within 6 hr to 5 × 10 −8 –1 × 10 −5 mol/L of 3OC6-HSL. Bright green fluorescence indicated the host cells. Furthermore, when the plasmid was transferred to wild-type Pseudomonas PhTA125 (an AHL-producing bacterium), it also showed both green and red fluorescence. This result demonstrates that this plasmid can be used to construct whole-cell indicators that can indicate the AHL response and spatial behaviors of microbes in a microenvironmental niche. [ABSTRACT FROM AUTHOR]

Abstract: The purpose of this study was to determine the interactions between arsenic (As) resistant bacteria and As, using surface-enhanced Raman scattering (SERS) and Fourier transform infrared (FTIR) spectroscopy. According to our 16S rDNA results, eight bacteria isolated from the environment can be identified to four genera (Arthrobacter, Pseudomonas, Sphingomonas, and Acinetobacter). The bacteria were separated into cell wall and protoplast in the study to assess the As(V) attack. The As(V) stress on bacteria could be identified with SERS, but not with FTIR. The bacteria in our study primarily resist As(V) through sequestration of As(V) by the cell wall. The change in SERS peaks and their relationships with cell wall suggested that As(V) mainly interacts with functional groups on the cell wall including polysaccharides and flavin derivates. [Copyright &y& Elsevier]

Environments with high-salt concentrations are often populated by dense microbial communities. Halophilic microorganisms can be isolated from different saline environments and different strains even belonging to the same genus have various applications. Wastewater and soil rich in both organic matter and salt are difficult to treat using conventional microorganisms typically found in wastewater treatment and soil bioremediation facilities. Studies on decontaminative capabilities and decontamination pathways of organic contaminants (i.e., aromatic compounds benzoate, cinnamate, 3-phenylpropionate, 4-hydroxybenzoic acid), heavy metals (i.e., tellurium, vanadium), and nutrients in the biological treatment of saline wastewater and soil by halophilic microorganisms are discussed in this review. [Copyright &y& Elsevier]

Previous research has shown that Stenotrophomonas has the ability to reduce Cr(VI). In this study, we determined whether the reduction capacity of Cr(VI) is conserved in Stenotrophomonas rhizophila DSM14405T, a plant-growth-promoting rhizobacterium (PGPR). Our results show that S. rhizophila DSM14405T displays high Cr(VI) resistance at a minimal inhibitory concentration of 1000 mg/L. Furthermore, it completely reduced 50 mg/L Cr(VI) in 28 h at pH 7.5 at 30 °C. The results of X-ray photoelectron spectroscopy and high performance liquid chromatography coupled to inductively coupled plasma mass spectrometry analysis confirmed the ability of S. rhizophila DSM14405T to convert Cr(VI) to Cr(III), and indicated the adsorption and intracellular accumulation of Cr(III). Transcriptomic analysis revealed that in the presence or absence of Cr(VI), transcriptomes upon short-term exposure showed more differentially expressed genes than those after long-term exposure. GO and KEGG analyses showed that most of the differentially expressed genes were related to Cr(VI) resistance, including genes related to iron homeostasis, central metabolism, DNA repair and anti-oxidative stress, and sulfur metabolism. Highly Cr(VI)-resistant and reductive abilities of this PGPR strain render it a suitable candidate for combined plant-microbe remediation of chromium contaminants from soil. Image 1 • A PGPR Stenotrophomonas rhizophila , displays high Cr(VI) resistance and reductive ability. • S. rhizophila can completely reduce 50 mg/L Cr(VI) within 28 h. • High salt has less stress on S. rhizophila Cr(VI) reduction efficiency. • The mechanism underlying Cr(VI) resistance and reduction of S. rhizophila was revealed. • Results provide new candidate for combined plant-microbe remediation of Cr(VI). Mechanism underlying Cr(VI) resistance and reduction of a plant-growth-promoting rhizobacterium - Stenotrophomonas rhizophila. [ABSTRACT FROM AUTHOR]

Microbial fuel cells (MFCs) have become a promising technology for wastewater treatment accompanying electricity generation. Carbon and nitrogen removal can be achieved by utilizing the electron transfer between the anode and cathode in an MFC. However, large-scale power production and high removal efficiency must be achieved at a low cost to make MFCs practical and economically competitive in the future. This article reviews the principles, feasibility and bottlenecks of MFCs for simultaneous carbon and nitrogen removal, the recent advances and prospective strategies for performance improvement, as well as the involved microbes and electron transfer mechanisms. [ABSTRACT FROM AUTHOR]

• Chlorination of 5 common sulfamides followed the second-order kinetics. • A large number of reaction intermediates were detected for the first time. • Chlorination solutions of SDZ, STZ and SMT severely inhibited bacteria growth. • Primary toxic intermediates in the chlorination solution were proposed. Many antibiotic disinfection byproducts have been detected but their toxicity has not been evaluated adequately. In this report, the chlorination reaction kinetics of five common sulfamides (SAs), reaction intermediates and their toxicity were investigated. Chlorination of sulfapyridine (SPD), sulfamethazine (SMT), sulfathiazole (STZ), and sulfisoxazole (SIZ) followed the second-order kinetics, and were degraded completely within 10 min. A large number of reaction intermediates were deteced by LC-MS, among which a total of 16 intermediates were detected for the first time. Toxicity of the five SAs chlorination solutions was evaluated separately by examining their effects on the growth rate of S. salivarius K12 , a commensal bacterium in the human digestive system. After 30 min chlorination, solutions of SMT, STZ and sulfadiazine (SDZ) each exhibited severe toxicity by inhibiting the bacteria growth completely, whereas the inhibition was only 50 % and 20 % by SIZ and SPD respectively. Based on the comparison between toxicity test results and mass spectra, three SA chlorination intermediates, m/z 187.2 (C 10 H 10 N 4), m/z 287.2 (C 9 H 7 N 3 O 4 S 2) and m/z 215 (C 7 H 10 N 4 O 2 S/C 12 H 14 N 4) were proposed to be the primary toxicants in the chlorination products. Our study demonstrated the power of combined approach of chemical analysis and toxicity testing in identifying toxic disinfection byproducts, and highlighted the ne ed for more research on the toxicity evaluation and risk assessment of antibiotic disinfection byproducts. [Display omitted] [ABSTRACT FROM AUTHOR]

• SOC bioavailability significantly differed among soil particle-size fractions. • SOC bioavailability of fine sand increased by 200 %, whereas clay reduced by 60 % • The porosity of fine sand was 60% of clay. • Abundances of soil elements of clay were 6–30 times higher than fine sand. • Microbial activity, mediated by soil morphology, affected SOC bioavailability. Despite the fact that physical and chemical processes have been widely proposed to explicate the stabilization mechanisms of soil organic carbon (SOC), thebioavailability of SOC linked to soil physical structure, microbial community structure, and functional genes remains poorly understood. This study aims to investigate the SOC division based on bioavailability differences formed by physical isolation, and to clarify the relationships of SOC bioavailability with soil elements, pore characteristics, and microbial activity. Results revealed that soil element abundances such as SOC, TN, and DOC ranked in the same order as the soil porosity as clay > silt ≥ coarse sand > fine sand in both top and sub soil. In contrast to silt and clay, which had reduced SOC bioavailability, fine sand and coarse sand had dramatically enhanced SOC bioavailability compared to the bulk soil. The bacterial and fungal community structure was significantly influenced by particle size, porosity, and soil elements. Copiotrophic bacteria and functional genes were more prevalent in fine sand than clay, which also contained more oligotrophic bacteria. The SOC bioavailability was positively correlated with abundances of functional genes, C degradation genes, and copiotrophic bacteria, but negatively correlated with abundances of soil elements, porosity, oligotrophic bacteria, and microbial biomass (p < 0.05). This indicated that the soil physical structure divided SOC into pools with varying levels of bioavailability, with sand fractions having more bioavailable organic carbon than finer fractions. Copiotrophic Proteobacteria and oligotrophic Acidobacteria, Firmicutes, and Gemmatimonadetes made up the majority of the bacteria linked to SOC mineralization. Additionally, the fungi Mortierellomycota and Mucoromycota, which are mostly involved in SOC mineralization, may have the potential for oligotrophic metabolism. Our results indicated that particle-size fractionation could influence the SOC bioavailability by restricting SOC accessibility and microbial activity, thus having a significant impact on sustaining soil organic carbon reserves in temperate agricultural ecosystems, and provided a new research direction for organic carbon stability. [ABSTRACT FROM AUTHOR]

As a major reservoir of antibiotics, animal manure contributes a lot to the augmented environmental pressure of antibiotic resistance genes (ARGs). This might be the first study to explore the effects of different ventilation types on the control of ARGs and to identify the relationships between archaeal communities and ARGs during the composting of dairy manure. Several ARGs were quantified via Real-time qPCR and microbial communities including bacteria and archaea were analyzed by High-throughput sequencing during vacuum-type composting (VTC) and positive-pressure composting (PPC). The total detected ARGs and class I integrase gene (intI1) under VTC were significantly lower than that under PPC during each stage of the composting (p < 0.001). The relative abundance of potential human pathogenic bacteria (HPB) which were identified based on sequencing information and correlation analysis decreased by 74.6% and 91.4% at the end of PPC and VTC, respectively. The composition of archaeal communities indicated that methane-producing archaea including Methanobrevibacter , Methanocorpusculum and Methanosphaera were dominant throughout the composting. Redundancy analysis suggested that Methanobrevibacter and Methanocorpusculum were positively correlated with all of the detected ARGs. Network analysis determined that the possible hosts of ARGs were different under VTC and PPC, and provided new sights about potential links between archaea and ARGs. Our results showed better performance of VTC in reducing ARGs and potential HPB and demonstrated that some archaea could also be influential hosts of ARGs, and caution the risks of archaea carrying ARGs. Unlabelled Image [ABSTRACT FROM AUTHOR]

The incomplete denitrification due to insufficient carbon resource in the wastewater treatment plants (WWTPs) resulted in low nitrogen removal efficiency, which has become a widespread problem in China and all around the world. Reducing the requirement of carbon source by manipulating the nitrogen removal pathway from conventional nitrification-denitrification to partial nitrification-denitrification is considered as an efficient solution. In this article, the feasibility of combining free nitrous acid (FNA) sludge treatment and DO control to achieve partial nitrification-denitrification in a continuous flow system (aerobic-anoxic-oxic process) using real sewage was assessed. The nitrite pathway was rapidly established in the experimental reactor within 23 days by simultaneously lowering DO concentration in aerobic zone to 0.5 mg/L and treating 30% of the activated sludge per day from the reactor in the FNA sludge treatment unit with FNA concentration of 1.2 mg N/L and exposure time of 18 h. The nitrite oxidizing bacteria (NOB) were efficiently washed out and the partial nitrification process could maintain stable in the experimental reactor even after cease of FNA treatment and increase of DO concentrations in the main stream to 1.5 mg/L, with an average nitrite accumulation rate of above 78%. In contrast, the nitrite accumulation rate was just around 58% during low DO concentrations phase and declined quickly to below 1% after the DO concentrations were increased to 1.5 mg/L in the control reactor which only utilized single strategy of DO control to achieve nitrite pathway. Moreover, a better sludge settleability and nitrogen removal performance could also be realized in the experimental reactor. The results of nitrifying bacteria activities and quantities detection demonstrated that although NOB activities in both reactors were effectively inhibited, a certain amount of NOB (6.26 × 106 copies/g MLSS) were remained in the control reactor and multiplied rapidly as the DO concentration increased, which might break down the partial nitrification. Furthermore, the quantity results of nitrogen cycling related functional genes showed that the increment of the ratio of nitrate reduced bacteria to total bacteria was 0.35% larger than that of nitric oxide bacteria in the control reactor, while those two ratios increased similarly by 1.11% and 1.12% in the experimental reactor, respectively, which might be one potential cause of reduction in N 2 O emission of nitrite pathway achieved by FNA-based technologies. Image 1 • Optimal FNA conc. + exposure time are determined to inactivate NOB and sustain AOB. • Nitrite pathway is built by FNA sludge treatment + DO control in AAO process. • High NAR and TN removal rate are achieved in long-term treating real sewage. • FNA treatment + DO control reach better SVI + process stability than DO control. • More nosZ genes are enriched by FNA treatment + DO control than DO control. [ABSTRACT FROM AUTHOR]

Abstract Quorum sensing (QS) regulation of the composition of ammonia-oxidising archaea (AOA) and ammonia-oxidising bacteria (AOB) communities and functions in wastewater treatment was investigated. Specifically, we explored the role of N -acyl- l -homoserine lactones (AHLs) in microbial community dynamics in activated sludge. On average, the specific ammonia-oxidising-rate increased from 1.6 to 2.8 mg NH 4 +-N/g MLSS/hr after treatment with long-chain AHLs for 16 days, and the addition of AHLs to sludge resulted in an increased number of AOA/AOB amoA genes. Significant differences were observed in the AOA communities of control and AHL-treated cultures, but not the AOB community. Furthermore, the dominant functional AOA strains of the Crenarchaeota altered their ecological niche in response to AHL addition. These results provide evidence that AHLs play an important role in mediating AOA/AOB microbial community parameters and demonstrate the potential for application of QS to the regulation of nitrogen compound metabolism in wastewater treatment. Graphical abstract AHLs have an important role in mediating AOA/AOB microbial community parameters, and this discovery shows possibility of applying QS to the regulation of nitrogen compound metabolism in wastewater treatment. Unlabelled Image [ABSTRACT FROM AUTHOR]

Ammonia (NH 3 ) volatilization is one of the primary pathways of nitrogen (N) loss from soils after chemical fertilizer is applied, especially from the alkaline soils in Northern China, which results in lower efficiency for chemical fertilizers. Therefore, we conducted an incubation experiment using an alkaline soil from Tianjin (pH 8.37–8.43) to evaluate the suppression effect of Trichoderma viride ( T. viride ) biofertilizer on NH 3 volatilization, and compared the differences in microbial community structure among all samples. The results showed that viable T. viride biofertilizer (T) decreased NH 3 volatilization by 42.21% compared with conventional fertilizer ((CK), urea), while nonviable T. viride biofertilizer (TS) decreased NH 3 volatilization by 32.42%. NH 3 volatilization was significantly higher in CK and sweet potato starch wastewater (SPSW) treatments during the peak period. T. viride biofertilizer also improved the transfer of ammonium from soil to sweet sorghum. Plant dry weights increased 91.23% and 61.08% for T and TS, respectively, compared to CK. Moreover, T. viride biofertilizer enhanced nitrification by increasing the abundance of ammonium-oxidizing archaea (AOA) and ammonium-oxidizing bacteria (AOB). The results of high-throughput sequencing indicated that the microbial community structure and composition were significantly changed by the application of T. viride biofertilizer. This study demonstrated the immense potential of T. viride biofertilizer in reducing NH 3 volatilization from alkaline soil and simultaneously improving the utilization of fertilizer N by sweet sorghum. [ABSTRACT FROM AUTHOR]

N -acyl-homoserine lactones (AHLs) serve as quorum-sensing signals, which control a number of bacterial processes in many proteobacteria. Here we report the effects of exogenous short-chain AHL on the denitrifying process of Paracoccus denitrificans , which are capable of aerobic and anaerobic growth by utilizing nitrate. The denitrification activity of these cells was monitored by measuring denitrification products (including nitrate, nitrite, and nitrous oxide), and the individual messenger ribonucleic acid (mRNA) levels of nitrate, nitrite, nitric oxide and nitrous oxide reductases. The results indicated that 2 μmol/L C6-homoserine lactone (HSL) has little effect on cell density under either anaerobic or aerobic culture conditions, and the nitrate reduction activity appeared slightly affected by N -hexanoyl-DL-homoserine lactone (C6-HSL). However, exogenous C6-HSL significantly affected the transcription of nitrite reductase and nitric oxide reductase genes in P. denitrificans regardless of the presence of oxygen, and N 2 O accumulation activity in P. denitrificans was suppressed by C6-HSL under aerobic condition. In contrast, exogenous C6-HSL stimulated the production of N 2 O under anaerobic condition, suggesting that the regulation of denitrification by quorum sensing may be important in N 2 O release. [ABSTRACT FROM AUTHOR]

The development of communities of three important composting players including actinobacteria, fungi and clostridia was explored during the composting of wheat straw for mushroom production. The results revealed the presence of highly diversified actinobacteria and fungal communities during the composting process. The diversity of the fungal community, however, sharply decreased in the mature compost. Furthermore, an apparent succession of both actinobacteria and fungi with intensive changes in the composition of communities was demonstrated during composting. Notably, cellulolytic actinomycetal and fungal genera represented by Thermopolyspora , Microbispora and Humicola were highly enriched in the mature compost. Analysis of the key cellulolytic genes revealed their prevalence at different composting stages including several novel glycoside hydrolase family 48 exocellulase lineages. The community of cellulolytic microbiota also changed substantially over time. The prevalence of the diversified cellulolytic microorganisms holds the great potential of mining novel lignocellulose decomposing enzymes from this specific ecosystem. [ABSTRACT FROM AUTHOR]

Immigrant bacteria located on leaf surfaces are important to the health of plants as well as to people who consume fresh fruits and vegetables. However, the spatial distribution and organization of these immigrant bacteria on leaf surfaces are still poorly understood. To examine the spatial organization of these strains, two bacterial strains on tobacco leaves: (1) an indigenous strain, Pseudomonas stutzeri Nov. Y2011 labeled with green fluorescent protein, and (2) an immigrant strain Pantoea agglomerans labeled with cyan fluorescent protein isolated from pear, were studied. Under moist conditions, P. agglomerans cells quickly disappeared from direct observation by laser-scanning confocal microscopy, although elution results indicated that large amounts of live cells were still present on the leaves. Following exposure to desiccation stress, particles of cyan fluorescent protein-labeled P. agglomerans were visible within cracked aggregates of P. stutzeri Nov. Y2011. Detailed observation of sectioned aggregates showed that colonies of immigrant P. agglomerans were embedded within aggregates of P. stutzeri Nov. Y2011. Furthermore, carbon-resource partitioning studies suggested that these two species could coexist without significant nutritional competition. This is the first observation of an immigrant bacterium embedding within aggregates of indigenous bacteria on leaves to evade harsh conditions in the phyllosphere. [ABSTRACT FROM AUTHOR]

Abstract: Systemic study on thermal dilute-acid hydrolysis of cotton straw has been conducted. The process of sequential two-step reaction has been established, which can greatly improve the utilization efficiency of lignocellulosic biomass. The hydrolyses were carried out in an 1L erlenmeyer flask placed in the pressure steam sterilizer, where the hydrolysis retention time (0–60min), liquid to solid ratio (8–14:1) and acid concentration (0–1mol/L) were examined for the first stage. Optimization of first stage hydrolysis is desirable to achieve the highest yield of the sugars from hemicellulose and also as a pretreatment for the second acid hydrolysis. The solid residuals were further dilute-acid (0.2mol/L) hydrolyzed in this study. This second-stage hydrolysis mainly completed the conversion of cellulose to levulinic acid and formic acid. At last, dilute-acid conversion of cotton straw to sugars (in the first stage), levulinic acid and formic acid (in the second stage) was completed. [Copyright &y& Elsevier]

Abstract: The short-chain fatty acids (SCFAs) accumulated in waste activated sludge (WAS) fermentation was adopted as an alternative extra carbon source for biohydrogen production in microbial electrolysis cells (MECs). WAS was pretreated by bi-frequency ultrasonic and the highest SCFAs were accumulated at 3rd day. Three groups of tests were conducted in single chamber MECs for H2 production under different SCOD concentrations. SCOD removals were up to 60% at diluted influent, but reduced to 50% at original concentration. Highest H2 yield was 1.2 mL H2/mg COD at 2-fold dilution with 155% energy efficiency. Results showed that >90% of acetate and ∼90% of propionate were effectively converted to hydrogen, and next were n-butyrate and n-valerate (at dilutions), but <20% of iso-butyrate and iso-valerate were converted. The overall biohydrogen recovery in this study was 120 ml H2/g VSS/d. This work shows a possibility of cascade utilization of WAS fermentation liquid and H2 generation in MEC. [Copyright &y& Elsevier]

Abstract: The phyllosphere is inhabited by large populations of epiphytic bacteria that are able to modulate their phenotypes and behavior by quorum sensing (QS). However, the impact of acyl-homoserine lactones (AHLs) involved in QS on the ecology of bacteria in their natural habitat remains unclear. Therefore, we used a bioassay and liquid chromatography–mass spectrometry to detect AHLs in the tobacco phyllosphere. Our results identified several AHLs in the tobacco phyllosphere, the majority of which were short-chain AHLs. Furthermore, the addition of an exogenous N-(3-oxohexanoyl) homoserine lactone (3OC6HSL), which is seen in the naturally occurring tobacco phyllosphere, generated variability in the composition of the bacterial community as determined by denaturing gradient gel electrophoresis (DGGE) analysis and phospholipid fatty acid (PLFA) analysis. Notably, the ratio of Gram-positive (GP) bacteria increased in response to treatment with 1 μM AHL, but decreased incipiently when treated with 10 μM AHL. These observations provide insight into the composition of the leaf-colonizing epiphyte community responsible for AHLs, particularly GP bacteria as they do not use AHLs as signaling molecules for QS. [Copyright &y& Elsevier]

Although pesticides have been extensively used for controlling insects and disease pathogens of plants, little is known regarding the impacts of applying these pesticides on the microbial community in the plant phyllosphere. Here, we report the effects of cypermethrin pesticide application upon the microbial community of the pepper plant phyllosphere. Assessments were made using culture-independent techniques including phospholipid fatty acid analysis (PLFA) and 16S rRNA gene directed Polymerase Chain Reaction with Denaturing Gradient Gel Electrophoresis (PCR–DGGE). During the 21 day greenhouse study, PLFA results indicated that both total and bacterial biomass increased after application of the pesticide. PLFA profiles also indicated that Gram-negative bacteria became predominant. DGGE analysis confirmed a significant change in bacterial community structure within the phyllosphere following the pesticide application where different dendrogram clusters were observed between control and treated samples. Phylogenetic analysis also suggested a change in bacterial phyla following treatment, where bands sequenced within control cultures were predominantly of the Firmicutes phylum, but those bands sequenced in the treated samples were predominantly members of the Bacteroidetes and γ-Proteobacteria phyla. In conclusion, this study revealed an increase in bacterial abundance and a shift in community composition within the pepper plant phyllosphere following the pesticide application, and highlighted the effective use of PLFA and PCR–DGGE for studying the effect of pesticides upon indigenous phyllosphere microbes. [Copyright &y& Elsevier]

Abstract: To reduce the cellobiose inhibition of exoglucanase and endogulcanase and enhance cellulose hydrolysis during simultaneous saccharification and fermentation (SSF), a β-glucosidase encoding gene named BGL1 was cloned from Saccharomycopsis fibuligera and integrated into the chromosomal rDNA region of the Saccharomyces cerevisiae industrial strain NAN-27 producing NAN-227. Compared with the parental strain, which had no detectable activity, the β-glucosidase specific activity in NAN-227 was 1.02IU/mg of protein. When cellobiose was used as the sole carbon source in a shake-flask, NAN-227 consumed 6.2g/L of cellobiose and produced 3.3g/L of ethanol in 48h. The yield was 0.532g/g. The parent strain only consumed 1.92g/L of cellobiose and no ethanol was detected. During the SSF of acid-pretreated corncobs NAN-227 produced 20g/L of ethanol at 72h, which was similar to the parent strain when 20IU of β-glucosidase/g of substrate was added. [Copyright &y& Elsevier]

Abstract: Protein adsorption onto solid substrates usually takes place in an irreversible fashion and this irreversible adsorption also occurs in some enzymatic reactions. In this work the adsorption behavior of intact β-1, 4-glucan-cellobiohydrolase (CBH I) from Trichoderma reesei onto microcrystalline cellulose was monitored by surface plasmon resonance and UV-spectral method. It was found that there existed reversible binding and irreversible binding of CBH I during its interaction with cellulose substrate. To evaluate the influence of adsorption on cellulose enzymatic hydrolysis, the reaction dynamics on pure cellulose were determined. A plot of the hydrolysis rate against the surface density of irreversibly adsorbed CBH I, revealed an inverse relationship in which an apparent decrease in the hydrolysis rate was observed with increasing surface density. Taken together, results presented here should be useful for modifying the binding characteristics of CBH I and making them more effective in cellulose hydrolysis. [Copyright &y& Elsevier]

Nitrification and denitrification are crucial processes in the nitrogen cycle, a vital microbially driven biogeochemical cycle. N -acyl-homoserine lactone (AHL)-mediated quorum sensing (QS) is widespread in bacteria and plays a key role in their physiological status. Recently, there has been an increase in research into how the AHL-mediated QS system is involved in nitrification and denitrification. Consequentially, the AHL-mediated QS system has been considered a promising regulatory approach in nitrogen metabolism processes, with high potential for real-world applications. In this review, the universal presence of QS in nitrifiers and denitrifiers is summarized. Many microorganisms taking part in nitrification and denitrification harbor QS genes, and they may produce AHLs with different chain lengths. The phenotypes and processes affected by QS in real-world applications are also reviewed. In wastewater bioreactors, QS could affect nitrogen metabolism efficiency, granule aggregation, and biofilm formation. Furthermore, methods commonly used to identify the existence and functions of QS, including physiological tests, genetic manipulation and omics analyses are discussed. [Display omitted] • AHL-mediated quorum sensing is widespread in nitrifiers and denitrifiers. • AHL-mediated quorum sensing system is ubiquitous in virous ecosystems. • There is scope for real-world application of quorum sensing. • Methods used in AHL-mediated quorum sensing researches were reviewed. [ABSTRACT FROM AUTHOR]

Yellow mealworms (Tenebrio molitor larvae) are capable of biodegrading polystyrene (PS) and low-density polyethylene (LDPE). This study tested biodegradation of one expanded PS (EPS) with a weight-average molecular weight (M w) 256.4 kDa and two LDPE foams with respective M w of 130.6 kDa (PE-1) and 288.7 kDa (PE-2) in T. monitor larvae obtained in Beijing, China. The larvae consumed EPS and both LDPEs over a 60 day. Fourier transform infrared spectroscopy and thermogravimetric analyses of frass confirmed the formation of new oxygen-containing functional groups, as well as a change in physical property and chemical modification, indicating that biodegradation of EPS and LDPE occurred. Gel permeation chromatography analysis confirmed broad depolymerization of EPS and PE-1 (i.e., a decrease in both M w and a number-average molecular weight (M n)) but revealed limited extent depolymerization of PE-2 (i.e. , increase in M n and decrease in M w). For all materials, the size-average molecular weight (M z) was decreased. Biodegradation and oxidation of EPS and LDPE were confirmed using FTIR and TGA analysis. Depression of gut microbes by the antibiotic gentamicin resulted in significant inhibition of EPS depolymerization but did not stop LDPE depolymerization, resulting in the increase in M n and revealing that PS biodegradation was gut microbe-dependent but LDPE biodegradation was less dependent or independent of gut microbes. Gut microbial community analysis indicated that, as expected, under different dietary conditions, the intestinal flora significantly shifted to communities associated with biodegradation of EPS and LDPE. The results indicated the complexity and limitation of biodegradation of plastics in plastics-eating T. molitor larvae. Image 1 • Biodegradation of PS and two LDPE with decreased M z by Tenebrio molitor larvae. • Broad depolymerization of PS and one LDPE with decreased both M w and M n. • Limited extent depolymerization of LDPE with decreased M w but increased M n. • The antibiotic gentamicin inhibited depolymerization of PS but not LDPE. • Distinct microbiomes observed with three different diets bran, PS, and LDPE. [ABSTRACT FROM AUTHOR]

• Biofertilizer reduced NH 3 emission in farmland by 44%. • Biofertilizer decreased the conversion of fertilizer nitrogen to NH 4 +-N. • Biofertilizer increased the abundance of bacterial amoA and comammox amoA. • Biofertilizer shifted the soil nitrogen cycling microbiomes. Excessive ammonia (NH 3) emitted from nitrogen fertilizer application in farmland have caused serious disturbance to global environment, including reduction of visibility, formation of regional haze, and increase of nitrogen deposition. Application of biofertilizer has been considered as an effective approach for soil improvement and agriculture sustainability. In this study, a field experiment was conducted to evaluate the potential of B. subtilis biofertilizer on mitigating NH 3 volatilization and to investigate the underlying mechanisms. Compared with organic fertilizer, the incorporation of B. subtilis biofertilizer reduced NH 3 volatilization by up to 44%. Moreover, the application of B. subtilis biofertilizer reduced the abundance of ureC gene, and increased the abundance of functional genes (bacterial amoA and comammox amoA) and ammonia-oxidizing bacteria (AOB). This indicated that the conversion of fertilizer nitrogen to NH 4 +-N was decreased and the nitrification process was increased. In brief, the application of B. subtilis biofertilizer reduced the "source" and increased the "sink" of NH 4 +-N, thus reducing the retention of NH 4 +-N in alkaline soil, and mitigating NH 3 volatilization. These results indicated that B. subtilis biofertilizer is an effective control strategy for agricultural NH 3 emission, maintaining high crop yield and mitigating environmental disturbance. [ABSTRACT FROM AUTHOR]

Nitrogen losses caused by excess fertilizer application in agriculture are one of the main sources of non-point pollution. Biofertilizer has been considered as an effective alternative to synthetic nitrogen fertilizer, but the effectiveness and mechanism for controlling non-point pollution remains unclear. In this study, the effect of biofertilizer containing Bacillus subtilis on nitrogen loss in agricultural soil was investigated. Compared with the application of urea alone, the strategy of substituting 50% urea with biofertilizer reduced the nitrogen loss from farmland soil by 54%. Moreover, this strategy also increased nitrogen use efficiency by 11.2% and achieved a 5.0% increase in crop yield. Application of biofertilizer decreased the abundance of bacterial amoA gene and increased the abundance of narG , nirS , nirK , and nosZ genes in soil. This implied a decrease in nitrification and an increase in denitrification. Thus, it reduced the accumulation of NO 3 −-N in soil and greatly reduced nitrogen runoff and leaching loss. In addition, biofertilizer decreased the abundance of nitrogen-fixing gene nifH by up to 2 times. Application of biofertilizer also increased the abundance of Bacteroidetes and Chloroflexi, which play important roles in degradation of soil organic matter. In conclusion, the biofertilizer regulated the microbial nitrogen transformation process in soil and reduced nitrogen loss from agroecosystems. • Biofertilizer reduced nitrogen loss in farmland by 54%. • Biofertilizer increased nitrogen utilization by 11.2% and yield by 5.0%. • Biofertilizer slowed nitrification and enhanced denitrification in soil. • Biofertilizer increased the abundance of Bacteroidetes and Chloroflexi. [ABSTRACT FROM AUTHOR]

• Niche differentiation of DAMO bacteria and archaea in a Tibetan alpine wetland is evidenced. • DAMO bacteria occupy a specific niche in surface soil and play a role in methane oxidation. • DAMO archaea play an important role in methane oxidation in subsurface soil. • Stratified methane oxidation by bacteria and archaea is a vital methane sink in wetlands. Denitrifying anaerobic methane oxidation (DAMO) is a vital methane sink in wetlands. However, the interactions and niche partitioning of DAMO bacteria and archaea in freshwater wetland soils, in addition to the interactions among microorganisms that couple methane and nitrogen cycling is still unclear, despite that these factors may govern the fate of methane and nitrogen in wetlands. Here, we evaluated the vertical distribution of DAMO bacteria and archaea in soil layers along with the potential interactions among populations in the methane-coupled nitrogen cycling microbial community of Tibetan freshwater wetlands. A combination of molecular biology, stable isotope tracer technology, and microbial bioinformatics was used to evaluate these interrelated dynamics. The abundances and potential methane oxidation rates indicated that DAMO bacteria and archaea differentially occupy surface and subsurface soil layers, respectively. The inferred interactions between DAMO bacteria and nitrogen cycling microorganisms within their communities are complex, DAMO bacteria apparently achieve an advantage in the highly competitive environment of surface soils layers and occupy a specific niche in those environments. Conversely, the apparent relationships between DAMO archaea and nitrogen cycling microorganisms are relatively simple, wherein high levels of cooperation are inferred between DAMO archaea and nitrate-producing organisms in subsurface soils layers. These results suggest that the vertical distribution patterns of DAMO bacteria and archaea enable them to play significant roles in the methane oxidation activity of different soil layers and collectively form an effective methane filtration consortium. [ABSTRACT FROM AUTHOR]