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Purpose The work aimed to investigate the effect of cow dung and cellulolytic bacteria on humic characteristics during municipal solid waste composting. Four Bacillus isolates (B. subtilis, B. tequilensis, B. venezuelans and B. amyloliquefaciens) sourced from dumpsite soil were formulated as consortium for the study. Methods Four treatments were considered with addition of bulking agents (ratio 1:7:6) to 15 kg MSW. Treatment Cs1 (control): only MSW, Cs2: MSWâ+âcellulolytic bacterial inoculum @ 5 ml (2âÃâ109 CFU mlâ1); Cs3âMSWâ+âcow dung slurry @ 1 kg (1:100 based on wet weight) and Cs4âMSWâ+âcellulolytic bacterial inoculum @ 5 ml (2âÃâ109 CFU mlâ1)â+âcow dung slurry @ 1 kg (diluted 1:100 based on wet weight). The analyses of humic acids were done by elemental analyzer, UV and Fourier transform infrared spectroscopy during 90 days of composting. Results MSW amended with consortia of effective microorganisms and cow dung slurry projected highest humification degree at 82.4% (Pâ

Following the extraction of essential oil, citrus (Mousambi, Kinnow, and Orange) peel wastes were used to produce pectin. The yield of essential oil and pectin was maximum in orange. Pectin was characterized by Fourier-transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) spectroscopy. The degree of esterification (DE) and methoxyl content (MC) was maximum in orange whereas, the equivalent weight was maximum in Mousambi. A significant increase (61.8%) in the Lactobacillus fermentum population was observed with pectin as compared with sugar. Three sources followed the Orange > Kinnow > Mousambi trend as a prebiotic source. It was attributed to higher DE as well as higher MC. Enhancement in the bacterial population was in the range of 79.16–87.50%. The present work confirms the potential of pectin as a probiotic source for the enhancement of the bacterial population. Thus, it has a large scope for use in the food industry targeting a circular economy.

Background: Oleaginous yeasts can be grown on different carbon sources, including lignocellulosic hydrolysate containing a mixture of glucose and xylose. However, not all yeast strains can utilize both the sugars for lipogenesis. Therefore, in this study, efforts were made to isolate dual sugar-utilizing oleaginous yeasts from different sources. Results: A total of eleven isolates were obtained, which were screened for their ability to utilize various carbohydrates for lipogenesis. One promising yeast isolate Trichosporon mycotoxinivorans S2 was selected based on its capability to use a mixture of glucose and xylose and produce 44.86 ± 4.03% lipids, as well as its tolerance to fermentation inhibitors. In order to identify an inexpensive source of sugars, nondetoxified paddy straw hydrolysate (saccharified with cellulase), supplemented with 0.05% yeast extract, 0.18% peptone, and 0.04% MgSO4 was used for growth of the yeast, resulting in a yield of 5.17 g L−1 lipids with conversion productivity of 0.06 g L−1 h−1. Optimization of the levels of yeast extract, peptone, and MgSO4 for maximizing lipid production using Box–Behnken design led to an increase in lipid yield by 41.59%. FAME analysis of single cell oil revealed oleic acid (30.84%), palmitic acid (18.28%), and stearic acid (17.64%) as the major fatty acids. Conclusion: The fatty acid profile illustrates the potential of T. mycotoxinivorans S2 to produce single cell oil as a feedstock for biodiesel. Therefore, the present study also indicated the potential of selected yeast to develop a zero-waste process for the complete valorization of paddy straw hydrolysate without detoxification.How to cite: Sagia S, Sharma A, Singh S, et al. Single cell oil production by a novel yeast Trichosporon mycotoxinivorans for complete and ecofriendly valorization of paddy straw. Electronic Journal of Biotechnology 2020;44. https://doi.org/10.1016/j.ejbt.2020.01.009. Keywords: Biodiesel, Fatty acids, Lignocellulosic biomass, Lignocellulosic hydrolysate, Lipid production, Lipogenesis, Oleaginous yeast, Paddy straw, Single cell oil, Trichosporon mycotoxinivorans, Yeast

Crude oil contamination of soil and water resources is a widespread issue. The present study evaluated the degradation of aliphatic hydrocarbons (C11–C36) in crude oil by 17 bacteria isolated from a crude oil–contaminated soil. The results suggested that Pseudomonas sp. and Bacillus amyloliquefaciens were the best hydrocarbon-degrading bacteria in the presence of surfactant Tween-80 (0.1% w/v). Based on the present investigation and a previous study, Pseudomonas sp. + B. amyloliquefaciens and fungus Aspergillus sydowii were identified as best oil degraders and were immobilized in alginate–bentonite beads, guargum–nanobenonite water dispersible granules (WDGs), and carboxy methyl cellulose (CMC)–bentonite composite. Sandy loam soil was fortified with 1, 2, and 5% crude oil, and total petroleum hydrocarbon (TPH) degradation efficiency of free cultures and bio-formulations was evaluated in sandy loam soils. Compared to a half-life (t1/2) of 69.7 days in the control soil (1% oil), free cultures of Pseudomonas sp. + B. amyloliquefaciens and A. sydowii degraded TPH with t1/2 of 10.8 and 19.4 days, respectively. Increasing the oil content slowed down degradation, and the t1/2 in the control and soils inoculated with Pseudomonas sp. + B. amyloliquefaciens and A. sydowii was 72.9, 14.7, and 22.2 days (2%) and 87.0, 23.4, and 30.8 days (5%), respectively. Supplementing soil with ammonium sulfate (1%) enhanced TPH degradation by Pseudomonas sp. + B. amyloliquefaciens (t1/2–10 days) and A. sydowii (t1/2–12.7 days). All three bio-formulations were effective in degrading TPH (1%), and the t1/2 was 10.7–11.9 days (Pseudomonas sp. + B. amyloliquefaciens and 14–20.2 days (A. sydowii) and were at par with free cultures. Microbial diversity analysis based on taxonomic markers and functional markers suggested that the bioaugmentation process helped keep soil in the active stage and restored the original microbial population to some extent. The present study concluded that bio-formulations of crude oil–degrading microbes can be exploited for its degradation in the contaminated environment.

The above ground growth of the plant is highly dependent on the belowground root system. Rhizosphere is the zone of continuous interplay between plant roots and soil microbial communities. Plants, through root exudates, attract rhizosphere microorganisms to colonize the root surface and internal tissues. Many of these microorganisms known as plant growth promoting rhizobacteria (PGPR) improve plant growth through several direct and indirect mechanisms including biological nitrogen fixation, nutrient solubilization, and disease-control. Many PGPR, by producing phytohormones, volatile organic compounds, and secondary metabolites play important role in influencing the root architecture and growth, resulting in increased surface area for nutrient exchange and other rhizosphere effects. PGPR also improve resource use efficiency of the root system by improving the root system functioning at physiological levels. PGPR mediated root trait alterations can contribute to agroecosystem through improving crop stand, resource use efficiency, stress tolerance, soil structure etc. Thus, PGPR capable of modulating root traits can play important role in agricultural sustainability and root traits can be used as a primary criterion for the selection of potential PGPR strains. Available PGPR studies emphasize root morphological and physiological traits to assess the effect of PGPR. However, these traits can be influenced by various external factors and may give varying results. Therefore, it is important to understand the pathways and genes involved in plant root traits and the microbial signals/metabolites that can intercept and/or intersect these pathways for modulating root traits. The use of advanced tools and technologies can help to decipher the mechanisms involved in PGPR mediated determinants affecting the root traits. Further identification of PGPR based determinants/signaling molecules capable of regulating root trait genes and pathways can open up new avenues in PGPR research. The present review updates recent knowledge on the PGPR influence on root architecture and root functional traits and its benefits to the agro-ecosystem. Efforts have been made to understand the bacterial signals/determinants that can play regulatory role in the expression of root traits and their prospects in sustainable agriculture. The review will be helpful in providing future directions to the researchers working on PGPR and root system functioning.

With the growing consumer demand for natural food products, including food flavors, efforts toward identifying biotechnological interventions for their production have increased tremendously. The present paper reviews the production of flavor compounds by microbial biosynthesis or biotransformation, and their enzymes involved in synthesis and conversion from progenitor substrates. More importantly, the use of abundant, inexpensive, and nutrient-rich lignocellulosic waste generated by the processing set-ups of agro-industries as a potential substrate for the microbial production of flavor compounds under solid-state fermentation is reviewed. The article provides insights regarding the development of an efficient and cost-effective process to produce important flavors from agroresidues. The biotechnological route will also help in safe and eco-friendly management of wastes generated from agriculture.

Abstract Background Saccharification is the most crucial and cost-intensive process in second generation biofuel production. The deficiency of β-glucosidase in commercial enzyme leads to incomplete biomass hydrolysis. The decomposition of biomass at high temperature environments leads us to isolate thermotolerant microbes with β-glucosidase production potential. Results A total of 11 isolates were obtained from compost and cow dung samples that were able to grow at 50 °C. On the basis of qualitative and quantitative estimation of β-glucosidase enzyme production, Bacillus subtilis RA10 was selected for further studies. The medium components and growth conditions were optimized and β-glucosidase enzyme production was enhanced up to 19.8-fold. The β-glucosidase from B. subtilis RA10 retained 78% of activity at 80 °C temperature and 68.32% of enzyme activity was stable even at 50 °C after 48 h of incubation. The supplementation of β-glucosidase from B. subtilis RA10 into commercial cellulase enzyme resulted in 1.34-fold higher glucose release. Furthermore, β-glucosidase was also functionally elucidated by cloning and overexpression of full length GH1 family β-glucosidase gene from B. subtilis RA10. The purified protein was characterized as thermostable β-glucosidase enzyme. Conclusions The thermostable β-glucosidase enzyme from B. subtilis RA10 would facilitate efficient saccharification of cellulosic biomass into fermentable sugar. Consequently, after saccharification, thermostable β-glucosidase enzyme would be recovered and reused to reduce the cost of overall bioethanol production process.

Organic farming needs to be promoted as a means of sustaining soil health and reducing the cost of farming, especially for small farmers. The present study deals with the effect of organic compost, prepared using Efficient Microorganism (EM) consortium and applied along with full or half of the recommended dose of chemical fertilizers, on the growth of Calendula and Marigold plants, soil physico-chemical parameters and soil enzyme activities. Soil enzyme activities were improved with the increase in the rate of EM compost application in both Calendula and Marigold. Carotenoid pigment increased by 46.11% and 12.19% with application of EM compost over the control in Calendula and Marigold flowers respectively. Soil humus, available nitrogen and organic carbon content also increased due to the supplementation of EM compost resulting in better soil fertility. For Calendula, treatment T5 (Half dose NPK + EM compost 20 000 kg⋅hm−2) was found to be the most promising in terms of acid phosphatase (82.63 µg p-Nitrophenyl Phosphate⋅g−1⋅h−1), dehydrogenase (10.46 µg Triphenyl Formazan⋅g−1⋅d−1) and β-glucosidase (0.30 IU⋅g−1) activities. In Marigold, treatment C (Half dose NPK + EM compost 5 000 kg⋅hm−2) was the most promising in terms of amendment in soil enzyme activities.

The rice-wheat cropping sequence is the major cropping system of India, which generates large quantities of crop residues. The disposal of paddy straw becomes a major concern in the rice belt of India, as it is burnt to clear the field for succeeding wheat crop. Incorporation of the residues in soil is not feasible because of insufficient time between harvesting of the rice and sowing of wheat, and immobilization of the nitrogen, which causes a reduction in the subsequent crop yield. Microbial interventions to accelerate the degradation may be a viable option for the effective management of farm residues. In this study, a field experiment including three treatments: residues removal (absolute control) and straw retention (@3t/ha) with/without inoculation of fungal consortium was undertaken at the farm of Indian Agricultural Research Institute, New Delhi during 2017-18. Application of fungal consortium (Coprinopsis cineria LA2 and Cyathus stercoreus ITCC 3745) alongwith straw incorporation resulted in a significant increase in the population of microbes. Higher activities of dehydrogenase (8.13 μg TPF /g/d), Carboxymethyl cellulase (0.46 IU/g of soil/d), xylanase (0.06 IU/g of soil/ d), FDA hydrolase (4.31μg fluorescein released /g/h) and alkaline phosphatase (242.98 μg PNP/g/h) enzymes were recorded in the soil of fungal consortium treated plot. Microbial intervention in residue management increased CO2 emission two to three fold within 15-60 days which indicates the role of inoculation in hastening the degradation process. Therefore, microbial priming can be a suitable option for in situ management of paddy straw.

Lignocellulosic biomass is the most abundant renewable source of energy that has been widely explored as second-generation biofuel feedstock. Despite more than four decades of research, the process of ethanol production from lignocellulosic (LC) biomass remains economically unfeasible. This is due to the high cost of enzymes, end-product inhibition of enzymes, and the need for cost-intensive inputs associated with a separate hydrolysis and fermentation (SHF) process. Thermotolerant yeast strains that can undergo fermentation at temperatures above 40°C are suitable alternatives for developing the simultaneous saccharification and fermentation (SSF) process to overcome the limitations of SHF. This review describes the various approaches to screen and develop thermotolerant yeasts via genetic and metabolic engineering. The advantages and limitations of SSF at high temperatures are also discussed. A critical insight into the effect of high temperatures on yeast morphology and physiology is also included. This can improve our understanding of the development of thermotolerant yeast amenable to the SSF process to make LC ethanol production commercially viable.

Water contamination is often reported in agriculturally intensive areas such as the Indo-Gangetic Plain (IGP) in south-eastern Asia. We evaluated the impact of the organic and conventional farming of basmati rice on water quality during the rainy season (July to October) of 2011 and 2016 at Kaithal, Haryana, India. The study area comprised seven organic and seven conventional fields where organic farming has been practiced for more than two decades. Water quality parameters used for drinking (nitrate, NO3; total dissolved solids (TDS); electrical conductivity (EC) pH) and irrigation (sodium adsorption ratio (SAR) and residual sodium carbonate (RSC)) purposes were below permissible limits for all samples collected from organic fields and those from conventional fields over the long-term (~15 and ~20 years). Importantly, the magnitude of water NO3 contamination in conventional fields was approximately double that of organic fields, which is quite alarming and needs attention in future for farming practices in the IGP in south-eastern Asia.

Economics of ethanol production from lignocellulosic biomass depends on complete utilization of constituent carbohydrates and efficient fermentation of mixed sugars present in biomass hydrolysates. Saccharomyces cerevisiae, the commercial strain for ethanol production uses only glucose while pentoses remain unused. Recombinant strains capable of utilizing pentoses have been engineered but with limited success. Recently, presence of endogenous pentose assimilation pathway in S. cerevisiae was reported. On the contrary, evolutionary engineering of native xylose assimilating strains is promising approach. In this study, a native strain S. cerevisiae LN, isolated from fruit juice, was found to be capable of xylose assimilation and mixed sugar fermentation. Upon supplementation with yeast extract and peptone, glucose (10%) fermentation efficiency was 78% with ~90% sugar consumption. Medium engineering augmented mixed sugars (5% glucose + 5% xylose) fermentation efficiency to ~50 and 1.6% ethanol yield was obtained with concomitant sugar consumption ~60%. Statistical optimization of input variables Glucose (5.36%), Xylose (3.30%), YE (0.36%), and peptone (0.25%) with Response surface methodology led to improved sugar consumption (74.33%) and 2.36% ethanol within 84 h. Specific activities of Xylose Reductase and Xylitol Dehydrogenase exhibited by S. cerevisiae LN were relatively low. Their ratio indicated metabolism diverted toward ethanol than xylitol and other byproducts. Strain was tolerant to concentrations of HMF, furfural and acetic acid commonly encountered in biomass hydrolysates. Thus, genetic setup for xylose assimilation in S. cerevisiae LN is not merely artifact of xylose metabolizing pathway and can be augmented by adaptive evolution. This strain showed potential for commercial exploitation.

β-glucosidase is a crucial element of the microbial cellulose multienzyme complex since it is responsible for the regulation of the entire cellulose hydrolysis process. Therefore, the aim of the present work was to explore the diversity and distribution of glycosyl hydrolase family 1 β-glucosidase genes in three different environmental niches including, Himalayan soil, cow dung and compost by metagenomic approach. Preliminary evaluation through metabolic profiling using BIOLOG based utilization patterns of carbon, nitrogen, phosphorus and sulphur revealed the environment and substrate specific nature of the indigenous microbial population. Furthermore, clonal library selection, screening and sequence analysis revealed that most of the GH1 β-glucosidase proteins had low identities with the available database. Analysis of the distribution of GH1 β-glucosidase gene fragments and β-glucosidase producing microbial community revealed the environment specific nature. The OTUs obtained from Himalayan soil and compost metagenomic libraries were grouped into 19 different genera comprising 6 groups. The cow dung sample displayed the least diversity of GH1 β-glucosidase sequences, with only 14 genera, distributed among three groups- Bacteroidetes, Firmicutes and Actinobacteria. The metagenomic study coupled with metabolic profiling of GH1 β-glucosidase illustrated the existence of intricate relationship between the geochemical environmental factors and inherent microbial community.

A proteolytic strain of Bacillus pumilus MP 27 was isolated from water samples of Southern ocean produced alkaline protease. Since protease production need expensive ingredients, an economically viable process was developed by using low cost carbon source, wheat straw, supplemented with peptone. This protease was active within temperature ranges 10˚C -70˚C at pH 9. This process was optimized by response surface methodology using a Box Bekhman design by Design Expert 7.0 software that increased the protease activity to 776.5 U/ml. Moreover, the enzyme was extremely stable at a broad range of temperature and pH retaining 69% of its activity at 50 ºC and 70% at pH 11. The enzyme exhibited excellent compatibility with surfactants and commercial detergents, showing 87% stability with triton X-100 and ̴ 100% stability with Tide commercial detergent. The results of the wash performance analysis demonstrated considerably good de-staining at 50ºC and 4ºC with low supplementation (109 U/ml). Molecular modeling of the protease revealed the presence of serine proteases, subtilase family and serine active site and further docking supported the association of catalytic site with the various substrates. Certainly, such protease can be considered as a good detergent additive in detergent industry with a possibility to remove the stains effectively even in a cold wash.

Microorganisms in the rhizosphere mediate the cycling of nutrients, their enhanced mobilisation and facilitate their uptake, leading to increased root growth, biomass and yield of plants. We examined the promise of beneficial cyanobacteria and eubacteria as microbial inoculants, applied singly or in combination as consortia or biofilms, to improve growth and yields of okra. Interrelationships among the microbial activities and the micro/macro nutrient dynamics in soils and okra yield characteristics were assessed along with the changes in the soil microbiome. A significant effect of microbial inoculation on alkaline phosphatase activity was recorded both at the mid-crop and harvest stages. Microbial biomass carbon values were highest due to the Anabaena sp. - Providencia sp. (CR1 + PR3) application. The yield of okra ranged from 444.6–478.4 g−1 plant and a positive correlation (0.69) recorded between yield and root weight. The application of Azotobacter led to the highest root weight and yield. The concentration of Zn at mid-crop stage was 60–70% higher in the Azotobacter sp. and Calothrix sp. inoculated soils, as compared to uninoculated control. Iron concentration in soil was more than 2–3 folds higher than control at the mid-crop stage, especially due to the application of Anabaena-Azotobacter biofilm and Azotobacter sp. Both at the mid-crop and harvest stages, the PCR-DGGE profiles of eubacterial communities were similar among the uninoculated control, the Anabaena sp. - Providencia sp. (CW1 + PW5) and the Anabaena-Azotobacter biofilm treatments. Although the profiles of the Azotobacter, Calothrix and CR1 + PR3 treatments were identical at these stages of growth, the profile of CR1 + PR3 was clearly distinguishable. The performance of the inoculants, particularly Calothrix (T6) and consortium of Anabaena and Providencia (CR1 + PR3; T5), in terms of microbiological and nutrient data, along with generation of distinct PCR-DGGE profiles suggested their superiority and emphasized the utility of combining microbiological and molecular tools in the selection of effective microbial inoculants.

The present investigation evaluated the effect of inoculating different cyanobacterial formulations on a set of hybrids of maize, in terms of plant defense enzyme activity, soil health parameters, Zn concentration, and yields. Microbial inoculation showed significant effects on accumulation of Zn in flag leaf, with A4 (Anabaena–Azotobacter biofilm) recording the highest values. Analysis of variance (ANOVA) indicated that both the hybrids and cyanobacterial treatments brought about significant variation in terms of glomalin-related soil proteins and polysaccharides in soil and the activity of defense enzymes in roots and shoots of the plants. Cyanobacterial inoculants—A4 (Anabaena–Azotobacter biofilm) and A1 (Anabaena sp.–Providencia sp., CW1 + PW5) enhanced the activity of peroxidase, PAL and PPO in roots, which also showed a positive correlation with Zn concentration in the flag leaf. Grain yield ranged from 7.0 to 7.29 t/ha among the different inoculants. Comparative analyses of treatments showed that A3 (Anabaena–Trichoderma-biofilmed formulation) and hybrid B8 (Bio-9681) were superior in terms of parameters investigated. This represents the first report on the genotypic responses of maize hybrids to cyanobacteria-based inoculants. Future research should focus on dissecting the role of root exudates and cyanobacteria-mediated Zn mobilization pathway in maize.

The influence of plant growth promoting bacteria (PGPB) and cyanobacteria, alone and in combination, was investigated on micronutrient enrichment and yield in rice–wheat sequence, over a period of two years. Analysis of variance (ANOVA) in both crops indicated significant differences in soil dehydrogenase activity and micronutrient enrichment in grains (Fe, Zn in rice, and Cu, Mn in wheat). The combined inoculation of Anabaena oscillarioides CR3, Brevundimonas diminuta PR7, and Ochrobactrum anthropi PR10 (T6) significantly increased nitrogen, phosphorus, and potassium (NPK) content and improved rice yield by 21.2%, as compared to the application of recommended dose of NPK fertilizers (T2). The treatment T5 (Providencia sp. PR3 + B. diminuta PR7 + O. anthropi PR10) recorded an enhancement of 13–16% in Fe, Zn, Cu, and Mn concentrations, respectively, in rice grains. In wheat, Providencia sp. PW5 (T6) recorded the highest yield (5.23 Mg ha−1) and significantly higher enrichment of Fe and Cu (44–45%) in the grains. This study highlighted the promise of combinations of cyanobacteria/bacteria and their synergistic action in biofortification and providing savings of 40–60 kg N ha−1. Future focus needs to be towards integrating such promising environment-friendly and environmentally sustainable options in nutrient management strategies for this cropping sequence.