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The worldwide increase of industrialization and reduction in the forest cover has led to the accumulation of harmful contaminants into the environment. One such “emerging” group of contaminants is phthalate esters that have been reported from all around the world. Di ethyl phthalate (DEP) has wide applications as plasticizers of polyvinyl chloride, and attributable to its endocrine disrupting and anti-androgenic activity. In agriculture, there is wide use of plastic films such as in mulching and greenhouse. Due to heat and other factors, DEP from plastic leaches down is difficult to degrade and enters the food chain. In the present study, nine different DEP degrading bacterial morphotypes were isolated from three soil samples collected from the Centre for Cultivated Protection Technology IARI, New Delhi, India. All the isolates were able to grow in DEP amended MS medium and finally three efficient bacterial isolates namely Achromobacter sp. strain DEPA3, Pseudomonas sp. strain DEPB3, and Enterobacter sp. strain DEPC1 were selected for the degradation of DEP in MS broth and soil microcosm individually as well as the mixed consortium. In MS broth, 84.91–96.14% DEP degradation was observed while in soil microcosm 81.16–92.39% degradation occurred within 30 days of inoculation. In the future, the potential isolates selected in the present study can be employed for bioremediation of contaminated sites.

The enormous availability of lignocellulosic biomass makes it a potential renewable feedstock for the continuous supply of second-generation bioethanol. The present study focuses on the exploitation of jute biomass left over after fiber extraction for bioethanol production by subjecting it to physical and chemical pretreatments (alkali, acid, ammonia fiber expansion, steam) followed by enzymatic saccharification and fermentation. The compositional analysis of jute biomass indicated that it contained cellulose (42.52 ± 5.54%), hemicellulose (12.24 ± 0.06%), lignin (31.58 ± 3.67%), and extractives (6.21 ± 0.42%). The biomass was subjected to different pretreatments and the structural and chemical changes along with crystallinity of cellulose were examined through scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction, respectively. Enzymatic saccharification of pretreated biomass revealed that among all the pretreatment methods, alkali (2% NaOH) treated substrate produced significantly higher amount of reducing sugar (19.51 g/L) compared with other pretreated biomass after 72 h of hydrolysis. The fermentation of the reducing sugars released during saccharification was carried out by a thermotolerant yeast Saccharomyces cerevisiae JRC6 resulting in 7.55 g/L of ethanol within 72 h of fermentation with 77.73% fermentation efficiency. Furthermore, lignin was aslo recovered from the spent liquor obtained after alkali pretreatment of the substrate and the remnant wash was analyzed by LC-MS for the presence of valuable platform chemicals. This study for the first time illustrates the potential of jute sticks as a feedstock for second-generation bioethanol.

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

Lactic acid is one of the most commonly used organic acids in various industries due to its versatile applications. To meet the market demand its production by various methods, such as chemically and microbiologically, is gaining significant interest. Chemically synthesized lactic acid (hydrolysis of acetonitrile) is generally a racemic mixture of D- and L-lactic acid which further needs purification for use in pharma and food industries. On the other hand, lactic acid produced by microbial fermentation is in an optically pure form of D- or L-lactic acid and does not require any further purification. Microbes used for lactic acid fermentation, such as bacteria, fungi, yeast, and algae, have the potential to use lignocellulosic biomass, organic agrowaste, kitchen waste, dairy, and petroleum industry waste as a feedstock. Therefore recycling of different organic waste for the production of lactic acid not only resolves the issues of waste management but may also help in reducing the production cost of lactic acid. These microorganisms ferment both pentose and hexose sugars to the desired product by two different pathways, i.e., homolactic and heterolactic fermentation pathways. In the course of these pathways, other than lactic acid there are a few other economically important platform chemicals (acetic acid, ethanol, butanol, etc.) also produced. Different microbes play a specific role at different stages of organic waste recycling to lactic acid. Briefly, lignocellulolytic and different glucoamylases-producing microbes (fungi and bacteria) are the main players in the initial steps of pretreatment and saccharification of biomass. After saccharification, when monomeric or dimeric sugar is released from the biomass, the fermentative lactic acid bacteria converts these sugars to the isomeric form of lactic acid. The obtained lactic acid is purified further by various mechanisms and the pure lactic acid then can be used in pharmaceutical, cosmetic, textile, and food industries.

Due to growing consumer preference towards natural ingredients in food products, the production of flavors by microbial biotransformation of agrowastes provides an eco-friendly, cost-effective and sustainable pathway for biovanillin production. In the present study, biovanillin was produced by microbial biotransformation of ferulic acid (FA) using Streptomyces sp. ssr-198. The strain was able to grow in glucose medium supplemented with 1 g/L FA and produce 20.91 ± 1.11 mg/L vanillin within 96 h, along with 5.78 ± 0.13 mg/L vanillic acid in 144 h. Estimation of enzymes involved in FA degradation detected maximum feruloyl-CoA synthetase activity (1.21 ± 0.03 U/mg protein) at 96 h and maximum vanillin dehydrogenase activity (0.31 ± 0.008 U/mg protein) at 168 h, with small amounts of ferulic acid esterase activity (0.13 ± 0.002 U/mg protein) in the fermentation medium. Further, the glucose deficient production medium supplemented with 3 g/L of ferulic acid when inoculated with Streptomyces sp. ssr-198 (6% wet weight) produced maximum vanillin (685 ± 20.11 mg/L) within 72 h at 37 °C under agitation (150 rpm) and declined thereafter. Furthermore, in a one-pot experiment, wherein crude ferulic acid esterase (700 IU/g of substrate) from Enterococcus lactis SR1 was added into 10% w/v wheat bran (natural source of ferulic acid) based medium and was inoculated with 1% w/v of Streptomyces sp. ssr-198 resulted in maximum vanillin production (1.02 ± 0.02 mg/g of substrate) within 60 h of incubation. The study provides an insight into synergistic effect of using FAE of E. lactis SR1 and Streptomyces sp. ssr-198 for bioproduction of biovanillin using agro residues. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13205-021-03006-0.

Exogenous addition of growth stimulants or other chemicals to soil-less medium is a common practice for enhancing biomass and productivity, and a promising amendment option can be cyanobacteria, a ubiquitous group of photosynthetic, plant growth promoting and agriculturally beneficial microorganisms, used as biofertilizers in agriculture. The performance of three nitrogen-fixing cyanobacterial cultures- Anabaena torulosa (BF1), Anabaena doliolum (BF4) and Anabaena laxa (RPAN8), through amendment to two media - namely rooting mix (cocopeat, vermiculite and perlite in 3:1:1) and sand contained in Pro-Trays was evaluated at fortnightly intervals up to 30 days. An enhancement, up to 2- to 3-fold in chlorophyll (as an index of photosynthetic biomass) and 30–45% IAA was observed in the extracts of cyanobacterium–amended media, over control; rooting mix was more promising as compared to sand. The addition of cyanobacteria also brought a significant enhancement of 30–40% in the availability of nitrogen and micronutrients–Mn, Cu, Zn and Fe in both media. Phytotoxicity studies with seeds of mustard, radish, maize and wheat, revealed no inhibition, highlighting the promise of these fortified rooting mixes as organic inputs in nursery propagation.

The present investigation aimed to utilize plant growth–promoting diazotrophic cyanobacteria as an option to raise the chrysanthemum varieties Pusa Aditya and Jaya in a nursery by co-culturing hydroponically. Fresh stem cuttings of chrysanthemum were planted in BG 11 medium (−N) which was inoculated to log-phase cultures of Anabaena torulosa (BF1), Anabaena doliolum (BF4), and Anabaena laxa (RPAN8) individually. Analyses of chrysanthemum growth and biometric/biochemical parameters after 30 days of co-cultivation revealed that co-culturing treatments performed significantly better, as compared with BG11 medium alone. Anabaena laxa brought about an increment of 27–40% in IAA production in the root tissues of both varieties grown in hydroponics. Quantification of biofilm formation on roots (measured as OD550) illustrated a two- to four-fold increment in the co-culture treatments. PEP carboxylase activity was significantly enhanced in root and shoot tissues of cuttings in Jaya, and the medium chlorophyll enhanced by several folds in both varieties. Significant increases in root dry biomass were recorded, which positively correlated with root protein (r = 0.992) in Pusa Aditya, illustrating the superiority of co-culturing as a promising option for nursery propagation. The economic benefits of BG 11 medium (without combined N) as a novel growth medium for growing the cyanobacterium and raising chrysanthemum nursery, in co-culturing mode, were also highlighted. Anabaena torulosa (BF1) performed well in both Pusa Aditya and Jaya, while Anabaena laxa (RPAN8) was significantly superior in Jaya. Future research is focused towards integration of such novel and cheap organic inputs in maintaining disease-free and nutrient-enriched plants in long-term experiments up to flowering stage.

Mesta crop biomass is one of the unexplored lignocellulosic feedstocks for second-generation bioethanol production. The compositional analysis of two mesta species, namely Hibiscus sabdariffa and H...

Co-utilization of xylose and glucose and subsequent fermentation using Saccharomyces cerevisiae could enhance ethanol productivity. Directed engineering approaches have met with limited success due to interconnectivity of xylose metabolism with other intrinsic, hidden pathways. Therefore, random approaches like protoplast fusion were used to reprogram unidentified mechanisms. Saccharomyces cerevisiae LN, the best hexose fermenter, was fused with xylose fermenting Pichia stipitis NCIM 3498. Protoplasts prepared using glucanex were fused under electric impulse and fusants were selected using 10% ethanol and cycloheximide (50 ppm) markers. Two fusants, 1a.23 and 1a.30 showing fast growth on xylose and tolerance to 10% ethanol, were selected. Higher extracellular protein expression observed in fusants as compared to parents was corroborated by higher number of bands resolved by twodimensional analysis. Overexpression of XYL1, XYL2, XKS and XUT4 in fusants as compared to S. cerevisiae LN as observed by RT-PCR analysis was substantiated by higher specific activities of XR, XDH and XKS enzymes in fusants. During lignocellulosic hydrolysate fermentation, fusants could utilize glucose faster than the parent P. stipitis NCIM 3498 and xylose consumption in fusants was higher than S. cerevisiae LN.

Lactic acid is an intermediate-volume specialty chemical, used in the production of biodegradable polymers and other chemicals. Although lactic acid production process is well established, however, the cost of production is very high. Therefore, in this study; starchy biomass (cassava) was hydrolyzed with in-house enzyme cocktail prepared from Aspergillus foetidus MTCC508 and Bacillus subtilis RA10. Process optimization using Taguchi experimental design helped to optimize the most effective ratio of fungal and bacterial amylase for effective saccharification of cassava. A higher sugar yield of 379.63 mg/gds was obtained under optimized conditions, using 30 U/gds of bacterial enzyme and 90 U/gds of the fungal enzyme at pH 4 within 48 h of saccharification. Among 11 lactic acid bacteria isolated, Lactobacillus fermentum S1A and Lactobacillus farraginis SS3A produced the highest amount of lactic acid 0.81 g/g and 0.77 g/g, respectively, from the cassava hydrolysate. The study proved the potential renewable source of cassava biomass as a source for fermentable sugars that can be fermented to lactic acid with high yield. In future, this cost-effective and environmental-friendly bioprocess can be upscaled for industrial lactic acid production. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s13205-020-02349-4) contains supplementary material, which is available to authorized users.

Ferulic acid is a known precursor for vanillin production but the significance of agro waste as substrates for its extraction, in combination with microbes is a less explored option. Various lactic acid bacteria were screened for the production of ferulic acid esterase (FAE) and Enterococcus lactis SR1 was found to produce maximum FAE (7.54 ± 0.15 IU/ml) in the synthetic medium under submerged fermentation. To make the process cost effective, various lignocellulosic agroresidues were evaluated for the production of FAE from the bacterium. It was found that wheat bran serves as the best substrate for FAE production (4.18 ± 0.12 IU/ml) from E. lactis SR1. Further, optimization of fermentation conditions for FAE production from E. lactis SR1 using wheat bran as carbon source led to an increase in the enzyme production (7.09 ± 0.21 IU/ml) by 1.5 fold. The FAE produced was used alone or in combination with commercial holocellulase for biological release of FA from the tested agroresidues. The highest release of FA (mg/g) by enzymatic extraction occurred in sugarbeet pulp (2.56), followed by maize bran (1.45), wheat bran (1.39) and rice bran (0.87), when both the enzymes (FAE and holocellulase) were used together. Alkaline extraction and purification of ferulic acid (FA) from these agro residues also showed that sugarbeet pulp contains the highest amount of FA (5.5 mg/g) followed by maize bran (3.0 mg/g), wheat bran (2.8 mg/g) and rice bran (1.9 mg/g), similar to the trend obtained in biological/enzymatic extraction of FA from these residues. Furthermore, the substrates were found to release higher reducing sugars when both commercial holocellulase and FAE were used in combination than by the use of holocellulase alone. Thus, FAEs not only release FA but also enabled hemicellulase and cellulase to release more sugars from plant material. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s13205-020-02360-9) contains supplementary material, which is available to authorized users.

Biofilm formation of a nitrogen-fixing cyanobacterium Anabaena torulosa with a beneficial fungus Trichoderma viride (An-Tr) was examined under laboratory conditions. A gradual enhancement in growth over A. torulosa alone was recorded in the biofilm, with 15–20% higher values in nitrogen fixation, IAA and exopolysaccharide production illustrating the synergism among the partners in the biofilm. To investigate the role of such biofilms in priming seed attributes, mesocosm studies using primed seeds of two maize inbred lines (V6, V7) were undertaken. Beneficial effects of biofilm (An-Tr) were recorded, as compared to uninoculated treatment and cyanobacterial consortium (Anabaena–Nostoc; BF 1-4) at both stages (7 and 21 DAS, days after sowing) with a significant increase of more than 20% in seedling attributes, along with 5–15% increment in seed enzyme activities. More than three- to fivefold higher values in nitrogen fixation and C-N mobilizing enzyme activities, and significant increases in leaf chlorophyll, proteins and PEP carboxylase activity were observed with V7-An-Tr biofilm. Cyanobacterial inoculation brought about distinct changes in the soil phospholipid fatty acid profiles (PLFA); particularly, significant changes in those representing eukaryotes and anaerobic bacteria. Principal component analyses illustrated the significant role of dehydrogenase activity and microbial biomass carbon and distinct elicited effects on soil microbial communities, as evidenced by the PLFA. This investigation highlighted the promise of cyanobacteria as valuable priming options to improve mobilization of nutrients at seed stage, modulating the abundance and activities of various soil microbial communities, thereby, enhanced plant growth and vigour of maize plants. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s13205-020-2141-6) contains supplementary material, which is available to authorized users.

Banana peel waste was explored as a substrate for single-cell oil production using a promising oleaginous yeast Rhodotorula glutinis NRRL Y-1091 and fungus Ganoderma wiiroense under solid-state versus submerged fermentation for 8 days. Higher productivity and yield of lipids of 0.020 g lipid/g starch was recorded in both types of fermentation, with the fungal isolate G. wiiroense as compared to R. glutinis. Amylase, β glucosidase and inulinase activity were also monitored, which followed a similar trend, with highest values on 6th or 8th day of incubation. Lipase activity was not detected in the crude extract of both strains. Inulinase activity was highest at 8th day incubation in submerged fermentation with the fungal isolate G. wiiroense. FAME analyses revealed that the composition of the lipids had promising potential as good-quality biodiesel. The high levels of inulinase activity in the yeast and fungal strains enhanced the production of monomeric sugars from inulin present in banana peel, which, in turn, facilitated greater conversion to lipids and stimulated bio-oil production.

Alpha-L-arabinofuranoside arabinofuranohydrolase (ARA), more commonly known as alpha-L-arabinofuranosidase (E.C. number 3.2.1.55), is a hydrolytic enzyme, catalyzing the cleavage of alpha-L-arabinose by acting on the non-reducing ends of alpha-L-arabinofuranosides, alpha-L-arabinans containing (1,3)- and/or (1,5)-linked arabinoxylans and arabinogalactans. ARA functions as debranching enzyme removing arabinose substituents from arabinoxylan and arabinoxylooligomers, thereby, boosting the hydrolysis of arabinoxylan fraction of hemicellulose and improving bioconversion of lignocellulosic biomass. Previously, comprehensive information on this enzyme has not been reviewed thoroughly. Therefore, the main aim of this review is to highlight the important properties of this interesting enzyme, microorganisms used for its production, and enhanced production using genetic engineering approach. An account on synergism with other biomass hydrolyzing enzymes and various industrial applications of this enzyme has also been provided along with an outlook on further research and development.

An investigation was undertaken to compare the effect of different concentrations of three metal nanoparticles i.e. silver (Ag), zinc oxide (ZnO) and copper oxide (CuO), on a cyanobacterium Calothrix elenkinii. Chlorophyll accumulation in C. elenkinii acclimatised to Ag NPs after 1 week at concentrations of 0.1 and 0.5 mg L−1, while it reduced at 1.0 mg L−1. A similar trend was recorded with CuO NPs, in terms of protein content with incubation time. Nitrogen-fixing potential also showed a gradual increase with Ag NPs, up to concentrations of 0.2 mg L−1 during incubation of 1 week, but sharply decreased at 0.5 mg L−1 after 48 h. Both the nitrogen-fixing potential and protein content were stimulated in the presence of CuO NPs. ZnO NPs, in general, were not compatible with the growth and metabolic activities of this cyanobacterium. Microscopic studies revealed the aggregation of NPs on the surface of C. elenkinii filaments, resulting in distinct morphological changes, particularly enhanced hormogonia and akinete formation. It is envisaged that with the increase in incubation period, C. elenkinii acclimatised to counteract the effect of Ag and CuO NPs and utilise them for its growth. The adaptive strategies of this cyanobacterium make it an ideal model system for future nanotoxicological studies.

Series of chitosan grafted zinc containing nanoclay polymer bio-composites (CZNCPBCs) with variable percentage (8%, 10% and 12%) of clay and nanoclay were synthesized by a novel method. Clays as well as CZNCPBCs were characterized through X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR). Release study of Zn2+ from CZNCPBCs in Zn deficient soils revealed that combination having 12% nanoclay showed slowest release rate. Olsen-P content was found maximum in 8% clay containing composite. However, combination containing 8% clay recorded highest equilibrium water absorbency as well as moisture content at a particular tension. Inoculation with fungal species revealed that Aspergillus spp. was more effective as compared with Trichoderma spp. in evolution of cumulative CO2-C, indirectly indicating biodegradability. CZNCPBCs were found to be promising as controlled release (CR) Zn2+ fertilizer formulation.

Microbial production of ethanol and 2,3-butanediol (2,3-BD) from agro-residues has been attracting interest because of their applications in various industries, including generation of biofuel mole...

Polylactic acid (PLA) is becoming one of the most paramount polymers due to its eco-friendly, biocompatible, and biodegradable nature. The feedstock (lactic acid) employed for PLA synthesis can be produced from agro-resources. Polylactic acid is expected to replace many conventional polymers, notably those used in food packaging and agricultural mulch. PLA processing techniques are ring-opening polymerization and direct condensation reactions. Mostly, polycondensation reaction uses a metal catalyst (Zn/Sn oxides), which is not safe for biomedical applications as it contains metal contamination. To make PLA more commercially appealing, ways to accelerate its degradation are constantly pursued. The work will include the synthesis of novel biodegradable metal-free bioplastic to solve the environmental plastic problems. A bioprocess was developed for manufacturing high molecular weight PLA using an enzymatic polymerization process. FTIR, NMR, GPC, XRD, DSC, TGA, and SEM analysis demonstrated the considerable change in the characteristic, morphological and thermal structures of PLA. Lactide formation was analyzed by FTIR and NMR study, followed by the monomer polymerization using lipase enzyme. The degree of crystallinity drops by 11.12% after degradation. GPC and TGA analysis confirmed the maximum MW loss and lowered Tmax by 46 °C after being buried in compost. SEM analysis showed the existence of cracks and voids after degradation. This new approach for the synthesis of metal-free degradable PLA would encourage its use for plastic and biomedical products in the future.

This study aims to improve the iron and zinc mobilization from soil to maize kernels using cyanobacteria-based formulations. Towards this, focused analyses of plant physiological attributes, nutrient availability in soil and its enrichment in the kernels of maize hybrid, Pusa Vivek QPM 9 Improved (G1) and its parental inbreds Pusa Maize Inbred Provitamin 1 (G2) and Pusa Maize Inbred Provitamin 2 (G3) was undertaken. The treatments included formulations of individual agriculturally beneficial organisms-a cyanobacterium- Anabaena torulosa, fungus-Trichoderma viride, and a bacterium Providencia sp. and their laboratory-developed biofilms - A. torulosa – Trichoderma viride (An-Tr) and A. torulosa – Providencia sp. (An-PW5). Application of An-Tr biofilm formulation led to 14- and 3.3-fold increase in nitrogenase activity and chlorophyll of soil respectively, over control, at the seedling stage. Hybrid (G1) recorded a significant increase of 1.2–1.5-fold in terms of nitrogenase activity over the parent genotypes. The highest zinc content in maize kernels, with a 1.34-fold increase over control, was recorded with An-Tr biofilm treatment, while T. viride increased kernel Fe content by 2.1-fold. Multivariate analyses illustrated a significant correlation of soil biological parameters-nitrogenase activity, chlorophyll, polysaccharides, Fe, Zn, with kernel Fe and Zn content in maize genotypes. Linear discriminant analyses validated the significant effects of individual microbial inoculation and biofilms. An-Tr biofilm- G1 (hybrid) combination can be a model system for in-depth analyses of beneficial effects of microbe-mediated biofortification of maize, leading to improved kernel quality and 25 % N savings.

Microbial conversion of agro-residues into valuable products such as GABA and lactic acid is of considerable environmental and biotechnological significance. In this study, twenty-nine lactic acid bacteria were isolated from traditional fermented milk and screened for lactic acid and GABA production. Among these, one strain LP-9, identified as Lactobacillus plantarum demonstrated co-production of GABA (0.86 g/L) and lactic acid (19.81 g/L) in De Man, Rogosa and Sharpe (MRS) broth supplemented with 1% monosodium glutamate (MSG). Under RSM optimized conditions, cumulative effect of factors influencing microbial product formation led to a two-fold increase in production of GABA (1.53 g/L) as compared to unoptimized conditions along with substantial production of lactic acid (21.87 g/L). Further, to develop an economical bioprocess on these lines, L. plantarum LP-9 was tested for its capability to utilize agro residues (wheat bran, rice bran and corn bran) and cassava (starchy food crop as control) in form of carbon source for GABA and lactic acid production using conditions optimized in RSM. The substrates were saccharified with enzyme cocktail containing α -amylase, amyloglucosidase, and cellulase followed by fermentation with L. plantarum LP-9 in MRS medium supplemented with 1% MSG but without sugar. The results showed that the saccharified agroresidues tested gave significant and comparable production of GABA (1.14–1.30 g/L) and lactic acid (22.83–29.82 g/L) as that obtained with cassava (1.39 g/L GABA and 31.76 g/L LA). This study illustrated the potential of isolate L. plantarum LP-9 to co-produce GABA and lactic acid from agro residues via biorefinery approach. The developed bioprocess will also help in safe, efficient and ecofriendly disposal of agriwastes.

Lignocellulosic biomass, a promising renewable energy source, can be used for the production of second generation bioethanol. Simultaneous saccharification and fermentation (SSF), the process which alleviates the problem of separate hydrolysis and fermentation (SHF), requires thermotolerant ethanologenic yeast for bioethanol production. Therefore, ten yeast strains isolated from diverse sources, belonging to various genera like Saccharomyces, Candida, Pichia and Wickerhamomyces were evaluated for their thermotolerance, sugar utilization pattern, inhibitor tolerance and ethanol production potential with glucose, xylose and alkali pretreated paddy straw. All the tested strains were found to be thermotolerant, capable of significant growth at 40°C. Candida tropicalis Y6 was capable of utilizing a wide range of sugars as compared with other yeast isolates. Strains of Candida showed better inhibitor tolerance as compared to Saccharomyces and Pichia strains and exhibited only 5.1-18.8% and 4.7-7.9% reduction in growth with furfural and 5-hydroxymethyl furfural, respectively. Saccharomyces cerevisiae JRC6, isolated from distillery waste, produced ethanol with 88.3% and 89.1% theoretical efficiency at 40°C and 42°C, respectively, from glucose. This strain also produced significantly higher amount of ethanol (3.8 g/L) with better fermentation efficiency (87.9%) from alkali pretreated paddy straw at 40°C, as compared with the other yeast strains. Therefore, S. cerevisiae JRC6, based on its ability to ferment sugars at a higher temperature, can be a promising candidate for production of ethanol from lignocellulosic biomass via SSF process.

The present investigation was aimed towards pretreatment optimization of corncob to maximize cellulose and hemicellulose recovery, followed by substrate selection for holocellulase production using psychrotolerant Aspergillus niger SH3. Dilute alkali pretreatment (1.5% NaOH) resulted in higher recovery of cellulose (59.66%) and hemicellulose (28.34%) from corncob, while corn stover proved to be the best substrate for holocellulase production. Further, saccharification was optimized by Box-Behnken design to select the suitable conditions for maximum sugar release from pretreated corncob. The optimum conditions for maximum sugar release were 8% (w/v) substrate loading, 11 FPU/gds enzyme loading at temperature 38 °C and pH 3.0 which resulted in 114.5% higher sugar yield (912 mg/gds of pretreated biomass) as compared with un-optimized conditions (425.35 mg/gds). Theoretical yield of 48.8% ethanol was achieved through simultaneous saccharification and fermentation (SSF) using pretreated corncob. This study illustrates the potential of different corn residues as a promising substrate for bioethanol production.

An atrazine degrading enrichment culture, a consortium of bacteria of genus Bacillus along with Pseudomonas and Burkholderia, was immobilized in sodium alginate and was used to study atrazine degradation in mineral salts medium (MSM), soil and wastewater effluent. Sodium alginate immobilized consortium, when stored at room temperature (24 ± 5°C), was effective in degrading atrazine in MSM up to 90 days of storage. The survival of bacteria in alginate beads, based on colony formation unit (CFU) counts, suggested survival up to 90 days and population counts decreased to 1/5th on 120 days. Comparison of atrazine degrading ability of the freely suspended enrichment culture and immobilized culture suggested that the immobilized culture took longer time for complete degradation of atrazine as a lag phase of 2 days was observed in the MSM inoculated with alginate immobilized culture. The free cells resulted in complete degradation of atrazine within 6 days, while immobilized cells took 10 days for 100% a...

The present study reports the diversity in extracellular proteins expressed by the filamentous fungus, Aspergillus terreus CM20 with respect to differential hydrolytic enzyme production profiles in submerged fermentation (SmF) and solid-state fermentation (SSF) conditions, and analysis of the extracellular proteome. The SSF method was superior in terms of increase in enzyme activities resulting in 1.5–3 fold enhancement as compared to SmF, which was explained by the difference in growth pattern of the fungus under the two culture conditions. As revealed by zymography, multiple isoforms of endo -β-glucanase, β-glucosidase and xylanase were expressed in SSF, but not in SmF. Extracellular proteome profiling of A. terreus CM20 under SSF condition using liquid chromatography coupled tandem mass spectrometry (LC–MS/MS) identified 63 proteins. Functional classification revealed the hydrolytic system to be composed of glycoside hydrolases (56%), proteases (16%), oxidases and dehydrogenases (6%), decarboxylases (3%), esterases (3%) and other proteins (16%). Twenty families of glycoside hydrolases (GH) (1, 3, 5, 7, 10, 11, 12, 15, 16, 28, 30, 32, 35, 43, 54, 62, 67, 72, 74 and 125), and one family each of auxiliary activities (AA7) and carbohydrate esterase (CE1) were detected, unveiling the vast diversity of synergistically acting biomass-cleaving enzymes expressed by the fungus. Saccharification of alkali-pretreated paddy straw with A. terreus CM20 proteins released high amounts of glucose (439.63 ± 1.50 mg/gds), xylose (121.04 ± 1.25 mg/gds) and arabinose (56.13 ± 0.56 mg/gds), thereby confirming the potential of the enzyme cocktail in bringing about considerable conversion of lignocellulosic polysaccharides to sugar monomers.

Cellulose is one of the most significant renewable energy sources present on earth and is also the most abundant biomolecule present in biomass. Hence producing indigenous cellulases for depolymerization of cellulose for use in various bioprocesses, namely biofuel production and commodity biochemical synthesis, is vital for the development of sustainable future biorefineries. Cellulolytic enzymes are a set of several enzymes, produced mainly by microorganisms both fungi and bacteria, that synergistically catalyze degradation of holocellulose-releasing oligosaccharides, cellobiose, and glucose units. Interestingly, cellulases are inducible enzymes, whose regulation is precisely regulated by activation and repression mechanisms. These inducible enzymes are produced only in the presence of complex cellulosic substrates, but repressed when simple sugars are present. The cellulosic substrates can either be pure substrates (cellulose powder) or raw lignocellulosic material. Lignocellulosic biomass, being plentiful as well as inexpensive, is usually the preferred substrate for the production of this enzyme system as compared to the pure substrates. Recent transcriptome profiling and quantitative proteomic approaches also reveal induction of specific proteins in the presence of utilizable lignocellulosic carbon sources by different microorganisms. This chapter discusses various pure and lignocellulosic substrates used for microbial cellulase production by either liquid submerged or solid-state fermentation.

The biorefinery concept involves production of fuel and chemicals from lignocellulosic biomass and thus can be considered as an analog to chemical refineries, that produce fuels and products from petroleum. Bioconversion of lignocellulosic residues involves the use of microbial hydrolytic enzymes, namely cellulases and hemicellulases, which release fermentable sugars from the delignified (pretreated) substrate. These enzymes are secreted in higher amounts by filamentous fungi to obtain energy from the biomass in natural habitats. Therefore, cellulases and xylanases to be used in biorefineries are usually produced from fungi. However, an efficient and economical process for the development of commercial biorefineries is still not formulated. This is because most of the present-day biomass conversion processes use mesophilic hydrolytic enzymes, which get denatured at increased temperatures, resulting in consumption of large amounts of enzyme and thus, half of the process cost in biorefineries is attributed to the enzyme production process. Therefore, employment of thermostable enzymes for hydrolysis of lignocellulosic biomass at higher temperatures can help in increasing reaction rates tremendously, thereby requiring lesser enzyme, in turn reducing process cost. In addition, consolidated bioprocessing (CBP) of untreated substrate by thermophilic filamentous fungi, which co-produce ligninases as well as cellulases and hemicellulases can deconstruct lignin as well as cellulose and hemicellulose to fermentable sugars at elevated temperature, leading to the feasibility of future biorefineries. This review discusses lignocellulosic bioconversion by the application of thermostable lignocellulolytic enzyme from thermophilic fungi into biofuels and commodity chemicals.

Production of platform chemicals has been advocated as a sustainable option to tackle the problems associated with agro-waste management. In this report, for the first time, efforts were made to effectively produce second-generation lactic acid from rice straw pretreated with imidazolium ionic liquid [EMIM][OAc] and subsequently fermented with a promising Lactobacillus plantarum SKL-22 strain saccharified with a commercial cellulase enzyme. Medium optimization was carried out to enhance the lactic acid (LA) yield by response surface methodology. In a 5 L bioreactor, the process was further upscale, and a yield increment of 1.11% was observed. The process using rice straw as substrate led to a LA yield of 36.75 g/L from L. plantarum SKL-22 in a single pot bioprocess. Overall, the above finding has shown the ability of L. plantarum SKL-22 to produce LA from the hydrolysate of rice straw. This study presented a novel environmental-friendly method for LA production.

Lactic acid is one of the essential platform chemicals, and despite the availability of a range of downstream processes, its effective recovery is still elusive. A phase partitioning process using n-butanol and a chaotropic salt ammonium sulphate was developed to recover lactic acid from the fermentation broth of Lactobacillus pentosus SKL-18. During the optimization of various process parameters, the extraction medium's pH was found to be critical, with 2.5 being the best. The optimized process resulted in a lactic acid yield of 86% and found it to be 93% pure. The purity and characteristics of lactic acid were confirmed by FTIR and NMR spectra. This solvent-based extraction procedure is an economical and straightforward downstream process for purifying lactic acid produced from agro- and bakery-residues. The pure lactic acid can further be used for enzymatic synthesis of high value-added product PLA, a biodegradable and biocompatible plastics.

Bioethanol has been recognized as a promising contemporary fuel. One of the most abundant renewable resources for bioethanol production is paddy straw with high carbohydrate content. A pretreatment step disintegrates the recalcitrant lignocellulosic structure in biomass, which facilitates the access of hydrolytic enzymes to the glucan macrostructure. Biological pretreatment is an eco-friendly alternative to harsh thermo-chemical pretreatment methodologies. In this study, paddy straw (rice variety Pusa 2511) was subjected to biological pretreatment with white-rot fungus, Trametes hirsuta and simultaneously with steam pretreatment at 121 °C. Resultant saccharification efficiencies of differentially pretreated paddy straw were compared to evaluate biological pretreatment. After pretreatment cellulose content in steam treated paddy straw was 39.5%, whereas for biological it was 37.6% and respective lignin contents were 14.2% and 4.7%. Lignin removal was substantially higher in biological pretreatment than steam pretreatment. The saccharification yields of biological pretreatment were at par with steam pretreated paddy straw. Highest saccharification efficiency was observed after 24 h, at 2% glucan loading, for both biological (76.5%) and steam pretreatment (74.1%). Maximum production of sugar (52.91 g L −1 ) was observed in biologically pretreated biomass at 10% glucan loading after 24 h. Fermentation of biomass hydrolysates with Saccharomyces cerevisiae , showed low ethanol production from biologically (0.86 g L −1 ) as well as steam pretreated biomass (1.13 g L −1 ) with fermentation efficiency ranging from 26 to 52%, suggesting presence of inhibitory factors necessitating detoxification of hydrolysates. This study, established biological pretreatment as feasible method for pretreatment and higher sugar yields.

Parthenium sp., a belligerent noxious herbaceous wasteland weed, became a threat to environment and biodiversity, so its management is necessary to prevent future problems. A new laccase producing strain of white-rot fungus Pseudolagarobasidium acaciicola LA 1 was isolated and evaluated for laccase production through solid-state fermentation of different lignocellulosics biomass. Parthenium biomass was selected as a suitable substrate for laccase production and optimization studies were undertaken. The maximum laccase (34,444 U/g of dry weight) was achieved with Parthenium biomass as solid substrate within 7 days at 30 °C under optimized condition. SDS-PAGE and zymography confirmed the presence of single laccase of 62.8 kDa. Laccase functioned optimally at pH 4.5 and temperature of 60 °C with ABTS (2,2′-Azino-bis-3-ethylbenzothiazoline-6-sulfonic acid). The enzyme retained 94 % of its original activity at 60 °C for 30 min and was found to be highly stable within the pH ranges 4.0–7.0 for 24 h. The presence of Cu+2 (10 mM) and ethanol (10 % v/v) enhanced the laccase activity. Crude laccase was applied for decolorization of Remazol Brilliant Blue R (RBBR) and Reactive Black 5 (RB5). The biodegradation was monitored by UV–vis spectroscopy and 90 % decolorization of RBBR (100 mg/L) was observed within 4 h of incubation. This study shows the potential of P. acaciicola for production of thermostable laccase using Parthenium biomass and its application for dye decolorization.

The current study was aimed at optimizing the fermentation conditions for efficient ethanol production from biologically pretreated paddy straw. The yeast strain Saccharomyces cerevisiae LN1 showed highest fermentation efficiency at pH 5.0 and temperature 30 °C. Paddy straw pretreated with fungus Myrothecium roridum LG7 was saccharified with indigenous holocellulase from Aspergillus niger SH3 producing total sugar yield of 26.14 mg/ml with 19.23 mg/ml of glucose. Enzymatic hydrolysate was then fermented using S. cerevisiae LN1 to observe the effect of nutrient supplementation (yeast extract, MgSO4·7H2O and (NH4)2SO4) on ethanol production. Higher ethanol was produced from saccharified material fermented without supplementation of any nutrient source. With the scale-up of ethanol production under optimized conditions in 7L bioreactor, 4.46 g/l of ethanol was produced with fermentation efficiency of 47.2 %. TLC of enzymatic hydrolysate confirmed the presence of p-coumaric acid, ferulic acid, vanillic acid, gallic acid and many other aromatic compounds and inhibitors in the saccharified material which limit fermentation efficiency of yeast strain. Thus, optimization of fermentation conditions can lead to development of a cost-effective process for efficient ethanol production, exploitation of which also requires removal of aromatic compounds and inhibitors which may hinder the ethanol production efficiency.

Impact of atmospheric CO 2 enrichment on soil aggregation, carbon and other nutrient availability and soil enzyme activities in relation to root and nodule biophysics in chickpea ( Cicer arietinum L.; Pusa-1105 genotype) was studied in an open top chamber experiment at IARI, New Delhi, India, continuing since 2003. Soil samples were collected at the end of the crop growing seasons of 2010–11 and 2011–12, and analyzed. Root growth and nodulation were also studied in these seasons. Soil C and P pools, and associated enzyme activities responded differently to CO 2 enrichment, while total soil N did not change. Soil labile C fractions viz., water soluble carbohydrate (WSC) and microbial biomass C (MBC) significantly increased, although recalcitrant C fraction declined marginally. The soil-CO 2 flux increased by 28%. Dehydrogenase and fluorescein diacetate hydrolysis activity in soil increased by 44% and 67% respectively; and the β-glucosidase activity enhanced by 20% under enriched CO 2 condition. The CO 2 enrichment induced root growth and N 2 -fixation by root nodules, which were evidenced by increase in legheamoglobin content and nitrogenase activity. Nodules were bulky and had higher starch and soluble sugar contents under enriched atmospheric CO 2 condition, allowing for greater N 2 -fixation. The rhizosphere C:N ratio, however, remained unaffected. It could be possible that larger partitioning of C to roots along with greater N 2 -fixation by nodules in chickpea might stabilize the net C:N ratio in the soil. Moreover, the increased soil biological activity under CO 2 enrichment resulted in marginal depletion of soil recalcitrant C with increase in labile C pools. These are likely to offset the stability of soil C pools in a legume-based agroecosystems under the enriched CO 2 condition in the semi-arid climate.

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 towards 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 artefact of xylose metabolizing pathway and can be augmented by adaptive evolution. This strain showed potential for commercial exploitation.

Production of lipid from oleaginous yeast using starch as a carbon source is not a common practice; therefore, the purpose of this investigation was to explore the capability of starch assimilating microbes to produce oil, which was determined in terms of biomass weight, productivity, and lipid yield. Saccharomyces pastorianus, Rhodotorula mucilaginosa, Rhodotorula glutinis, and fungal isolate Ganoderma wiiroense were screened for the key parameters. The optimization was also performed by one-factor-at-a-time approach. Considering the specific yield of lipid and cell dry weight yield, R. glutinis and R. mucilaginosa showed superiority over other strains. G. wiiroense, a new isolate, would also be a promising strain for starch waste utilization in terms of extracellular and intracellular specific yield of lipids. Extracellular specific yield of lipid was highest in R. glutinis culture (0.025 g g

Background Bioethanol obtained by fermenting cellulosic fraction of biomass holds promise for blending in petroleum. Cellulose hydrolysis yields glucose while hemicellulose hydrolysis predominantly yields xylose. Economic feasibility of bioethanol depends on complete utilization of biomass carbohydrates and an efficient co-fermenting organism is a prerequisite. While hexose fermentation capability of Saccharomyces cerevisiae is a boon, however, its inability to ferment pentose is a setback. Results Two xylose fermenting Kodamaea ohmeri strains were isolated from Lagenaria siceraria flowers through enrichment on xylose. They showed 61% glucose fermentation efficiency in fortified medium. Medium engineering with 0.1% yeast extract and peptone, stimulated co-fermentation potential of both strains yielding maximum ethanol 0.25 g g−1 on mixed sugars with ~ 50% fermentation efficiency. Strains were tolerant to inhibitors like 5-hydroxymethyl furfural, furfural and acetic acid. Both K. ohmeri strains grew well on biologically pretreated rice straw hydrolysates and produced ethanol. Conclusions This is the first report of native Kodamaea sp. exhibiting notable mixed substrate utilization and ethanol fermentation. K. ohmeri strains showed relevant traits like utilizing and co-fermenting mixed sugars, exhibiting excellent growth, inhibitor tolerance, and ethanol production on rice straw hydrolysates. Electronic supplementary material The online version of this article (10.1186/s13065-018-0375-8) contains supplementary material, which is available to authorized users.

Enzymatic hydrolysis is the most crucial step in bioconversion of lignocellulosic biomass to ethanol as efficient conversion of polymers to fermentable sugars determines final ethanol concentration. Cellulase complex used for commercial biomass hydrolysis is mostly derived from Trichoderma sp. and contains β-glucosidase

Rice straw is the most abundant agricultural residue on a global scale and is widely available as feedstock for cellulosic fuel production. However, it is highly recalcitrant to biochemical deconstruction and also generates inhibitors that affect enzymatic saccharification. Rice straw from eastern Arkansas was subjected to dilute acid pretreatment (160 °C, 48 min and 1.0% sulfuric acid) and solid-state fermentation with two lignocellulolytic fungi, Trametes hirsuta and Myrothecium roridum, and their saccharification efficacies were compared. T. hirsuta and M. roridum were tested separately; pretreatment of rice straw with either strain for seven days resulted in 19 and 70% enrichment of its holocellulose content, respectively. However, liquid chromatography analysis of the alkali extracts showed significant differences in cell wall degradation by T. hirsuta and M. roridum. T. hirsuta removed 15% more phenolic compounds and 38% more glucan than M. roridum, while M. roridum removed 77% more xylan than T. hirsuta. Fungal and dilute acid pretreated biomass was then hydrolyzed using Accellerase® 1500, a saccharification cocktail. Saccharification efficiency of M. roridum was 37% higher than that of dilute acid pretreatment of rice straw, requiring 8% lower enzyme loading and 50% shorter enzymatic hydrolysis duration. Alkali extraction of fungal pretreated biomass also yielded 10–15 g kg−1 of acid precipitable polymeric lignin (APPL), which is a valuable co-product for biorefineries. In comparison to dilute acid pretreatment, fungal pretreatment could be a cost-effective alternative for the degradation of recalcitrant biomass, such as rice straw.

Nutrient management practices play a significant role in improving the nutritional quality of tomato. The present study deals with the evaluation of compost prepared using Effective Microorganisms (EM), on antioxidant and defense enzyme activities of Tomato (Lycopersicon esculentum). A field experiment with five treatments (control, chemical fertilizer and EM compost alone and in combination) was conducted in randomized block design. An increment of 31.83% in tomato yield was recorded with the combined use of EM compost and half recommended dose of chemical fertilizers (N50P30K25+EM compost at the rate of 5tha−1). Similarly, fruit quality was improved in terms of lycopene content (35.52%), antioxidant activity (24–63%) and defense enzymes activity (11–54%), in tomatoes in this treatment as compared to the application of recommended dose of fertilizers. Soil microbiological parameters also exhibited an increase of 7–31% in the enzyme activities in this treatment. Significant correlation among fruit quality parameters with soil microbiological activities reveals the positive impact of EM compost which may be adopted as an eco-friendly strategy for production of high quality edible products.

A biosurfactant producing isolate of Stenotrophomonas maltophilia (BR-12) was isolated from crude oil-contaminated soil from Vadodara oil refinery (India) and characterized on the basis of biochemical tests and identified by 16S rRNA sequencing. It was also assessed for its Pyrene bioremediation potential under submerged conditions in minimal media spiked with Pyrene at 20, 50, and 100 µg mL−1. Analysis of microbial growth parameters revealed that BR-12 grew best at 50 µg mL−1 Pyrene concentration, leading to 87 % degradation of Pyrene within 20 days and production of high amount of biosurfactant (2.2 g L−1). Since biosurfactant production ability of bacteria can play a major role in enhancing its ability to degrade Pyrene, this promising strain needs to be further exploited in bioremediation of PAH-contaminated sites.

Low cost agro-waste biosorbents namely eucalyptus bark (EB), corn cob (CC), bamboo chips (BC), rice straw (RS) and rice husk (RH) were characterized and used to study atrazine and imidacloprid sorption. Adsorption studies suggested that biosorbents greatly varied in their pesticide sorption behaviour. The EB was the best biosorbent to sorb both atrazine and imidacloprid with KF values of 169.9 and 85.71, respectively. The adsorption isotherm were nonlinear in nature with slope (1/n) values

Second generation biofuel production has been appeared as a sustainable and alternative energy option. The ultimate aim is the development of an industrially feasible and economic conversion process of lignocellulosic biomass into biofuel molecules. Since, cellulose is the most abundant biopolymer and also represented as the photosynthetically fixed form of carbon, the efficient hydrolysis of cellulose is the most important step towards the development of a sustainable biofuel production process. The enzymatic hydrolysis of cellulose by suites of hydrolytic enzymes underlines the importance of cellulase enzyme system in whole hydrolysis process. However, the selection of the suitable cellulolytic enzymes with enhanced activities remains a challenge for the biorefinery industry to obtain efficient enzymatic hydrolysis of biomass. The present review focuses on deciphering the novel and effective cellulases from different environmental niches by unculturable metagenomic approaches. Furthermore, a comprehensive functional aspect of cellulases is also presented and evaluated by assessing the structural and catalytic properties as well as sequence identities and expression patterns. This review summarizes the recent development in metagenomics based approaches for identifying and exploring novel cellulases which open new avenues for their successful application in biorefineries.

Cold tolerant microbes play a pivotal role in the decomposition of cellulosic biomass in temperate environments. This study was aimed to evaluate β-glucosidase production from psychrotolerant microorganisms isolated from cold desert soil of the Kargil district, Himalayan region, India. A total of 12 morphotypes were isolated at 4 °C and, based on qualitative screening, seven isolates were selected for molecular identification and phenotypic microarray. Pseudomonas lutea BG8 was selected based on its β-glucosidase production potential. The characterization of β-glucosidase revealed the alkali-tolerant nature of the enzyme with a temperature optimum at 40 °C and ability to retain considerable activity over a broad pH range (5–10). The enzyme retained 95.15% activity even in the presence of 1000 mM glucose, indicating an absence of feedback inhibition and high glucose tolerance. The enzyme stability experiment revealed that the β-glucosidase enzyme retained 49.96% activity at pH 5 and 30 °C after 16 h of incubation. The Km and kcat of the β-glucosidase enzyme were found to be 0.636 ± 0.103 mM and 102.7 ± 0.004 s−1, respectively. The cold temperature active β-glucosidase from P. lutea BG8 was found to be highly efficient for bioconversion of cellobiose to ethanol along with S. cerevisiae by simultaneous saccharification and fermentation process with 91.42% (0.49 g ethanol per g cellobiose) fermentation efficiency at 4 °C. This novel β-glucosidase can lead to considerable energy savings due to its lower temperature optimum, as compared to commercial β-glucosidase.

The present work describes the secretome profiling of a phytopathogenic fungus, Phoma exigua by liquid chromatography coupled tandem mass spectrometry (LC–MS/MS) based proteomics approach to highlight the suites of enzymes responsible for biomass hydrolysis. Mass spectrometry identified 33 proteins in the Phoma secretome when grown on α-cellulose as the sole carbon source. The functional classification revealed a unique extracellular enzyme system mainly belonging to the family of glycosyl hydrolase proteins (52%). This hydrolytic system consisted of cellulases (endo-1,4-β-glucanase, cellobiohydrolase I, exoglucanase, and β-glucosidase), hemicellulases (1,4-β-xylosidase and endo-1,4-β-xylanase) and other hypothetical proteins including GH3, GH5, GH6, GH7, GH11, GH20, GH32 and GH54. The synergistic action of this enzyme cocktail was assessed by the saccharification of alkali treated wheat straw. Since the Phoma secretome has limited β-glucosidase activity, it was supplemented with commercial β-glucosidase. After supplementation, this enzyme complex resulted in high yields of glucose (177.2 ± 1.0 mg/gds), xylose (209.2 ± 1.5 mg/gds) and arabinose (25.2 ± 0.3 mg/gds). The secretome analysis and biomass hydrolysis by P. exigua revealed its unique potential as a source of hydrolytic enzymes for lignocellulosic biomass hydrolysis.

The aim of this work was to evaluate glycosyl hydrolases produced by diverse thermophilic fungal strains for saccharification of alkali and biologically (Trametes hirusita/Myrothecium roridum) treated Parthenium hysterophorus and rice straw. The compositional analysis of hydrolysates by HPLC showed distinct profiles of hexose, pentose and oligomeric sugars. Malbranchea cinnamomea was most efficient source of glycosyl hydrolases producing 283.8, 35.9, 129.6, 27,193, 4.66, 7.26 (units/gds) of endoglucanase, cellobiohydrolase, β-glucosidase, xylanase, α-αrabinofuranosidase and β xylosidase, respectively. The saccharification of alkali and biologically treated carrot grass by culture extract of M. cinnamomea was further enhanced by supplementation of β-glucosidase produced by Aspergillus sp. mutant “O”. The resultant hydrolysates containing glucose/xylose were fermented efficiently to ethanol by Saccharomyces cerevisiae owing to presence of xylose isomerase (0.8 units/gds) activity in culture extract of M. cinnamomea resulting in production of 16.5 and 15.0 g/l of ethanol from alkali treated rice straw and carrot grass, respectively.

Xenorhabdus indica KB-3, a well-known protease producer, was isolated from its entomopathogenic nematode symbiont Steinernema thermophilum. Since medium constituents are critical to the protease production, the chemical components of the selected medium (soya casein digest broth) were optimized by rotatable central composite design (RCCD) using response surface methodology (RSM). The effects of all five chemical components (considered as independent variables), namely tryptone, soya peptone, dextrose, NaCl, and dipotassium phosphate, on protease production (dependent variable) were studied, and it was found that tryptone and dextrose had maximum influence on protease production. The protease production was increased significantly by 66.31% under optimal medium conditions (tryptone—5.71, soya peptone—4.9, dextrose—1.45, NaCl—6.08, and dipotassium phosphate—0.47 in g/L). To best of knowledge, there are no reports on optimization of medium component for protease production by X. indica KB-3 using RSM and their application in fibrinolysis. This study will be useful for industrial processes for production of protease enzyme from X. indica KB-3 for its application in the field of agriculture and medicine.

Dimethyl phthalate (DMP) a common environmental pollutant is well known for its endocrine disrupting activities. Wide spread use of the plastics and pesticides in agriculture have resulted in DMP pollution in soils. An endosymbiotic bacteria Xenorhabdus indica isolated from entomopathogenic nematode Steinernema thermophilum was investigated for biodegradation of DMP. Biodegradation experiment was conducted for 12 days in minimal salt medium supplemented with beef extract. Quantification of residual DMP by High performance liquid chromatography (HPLC) revealed that maximum degradation (98.75%) occurred at 9th day of incubation along with higher esterase activity (46.94 IU/ml) and growth of bacteria (263.75 μg/ml). The efficacy of purified esterase for degradation of DMP was also investigated. It was observed that enzyme alone transform more than 25.6% of DMP into mono-methyl phthalate (MMP) and phthalic acid (PA) within 24 h, which confirms its role in degradation of DMP. Activity of carboxyl esterase enzyme was also positively correlated (r = 0.88) with biodegradation of DMP. Xenorhabdus completely mineralized the DMP as the two intermediates mono-methyl phthalate (MMP) and phthalic acid were not detected after the incubation period of 12 days. The results suggest that the X. indica was highly efficient in degrading DMP and can be employed for bioremediation of contaminated sites.

Different types of agro-industrial or household food processing wastes were assessed for their suitability as growth substrates using a set of oleaginous yeasts, for maximizing the production of lipids and useful enzymes under submerged fermentation (SmF). Minimal medium (pH 5.0) containing different wastes (10% w/v) were inoculated with different yeast strains and incubated at 30 °C for 8 days in an incubator shaker (120 rpm). The processing wastes (potato peel, banana peel, cassava peel, corn residue, rice husk, wheat bran, yam peel and barley husk) utilized, without any pre-treatment, were found to support both microbial growth and lipid production. Lipid productivity was observed to be higher in Cryptococcus curvatus as compared to Rhodotorula mucilaginosa , Saccharomyces pastorianus , Trichosporon cutaneum , Lipomyces starkeyi and Rhodotorula glutinis . Among the different substrates, wheat bran proved to be the best substrate for C. curvatus, as it resulted in the production of 16.0 g lipid/g starch, followed by banana peel yielding 14.3 g lipids/g starch. Interestingly, all the cultures (yeast and fungal) were found to exhibit activity of cellulases, as well as amylase and inulinase, which illustrates the novelty of the study and the viability of the technology for lipid production. Positive correlation between lipid productivity and enzyme activities further highlights the promise of these strains. These research findings illustrate the environmental friendly and alternate use of agro-industrial and household food processing wastes, towards their valorization as substrates for commercial single cell oil production.