Lignocellulosic Substrates Research Articles

Biodegradation of oil palm empty fruit bunch during cultivation of Volvariella volvacea

AbstractBiodegradation of cellulose, lignin, and hemicellulose from oil palm empty fruit bunches (OPEFB) by straw mushroom (Volvariella volvacea) was investigated. The present research mainly focused on the effects of effective microorganism (EM) treatment (M) and composting duration of OPEFB (C) on straw mushroom production. Two main stages were involved in this research. The first stage was emphasized on the V. volvacea culture process while the second stage was to evaluate the chemical properties of the OPEFB. Zero percent EM solution increased the OPEFB decomposition rate significantly for cellulose and slightly for hemicellulose. The EM solution of 20% increased the OPEFB decomposition rate significantly for hemicellulose after 5 days of composting. In contrast, 10% EM solution increased the OPEFB decomposition rate significantly for cellulose and lignin that were composted for 5 days and for hemicellulose that were composted for 10 and 15 days. The introduction of different EM solutions and varied composting days significantly affected the final compositions of the lignocellulose degraded by the V. volvacea. Most of the lignocellulose composition had positive correlation which depend on the nature of lignocellulose substrates. The final composition of cellulose, lignin, and hemicellulose in the spent OPEFB on average were 44.17 ± 0.04%, 22.66 ± 0.03%, and 11.39 ± 0.04%. Conversely, the raw OPEFB composition were 53.62% + 0.06%, 32.68% + 0.03%, and 15.23% + 0.19%. Based on the reduced percentage of the lignocelluloses, V. volvacea cultivation on OPEFB proved to be a good alternative in degrading biowastes.

LPMO-supported saccharification of biomass: effects of continuous aeration of reaction mixtures with variable fractions of water-insoluble solids and cellulolytic enzymes

BackgroundHigh substrate concentrations and high sugar yields are important aspects of enzymatic saccharification of lignocellulosic substrates. The benefit of supporting the catalytic action of lytic polysaccharide monooxygenase (LPMO) through continuous aeration of slurries of pretreated softwood was weighed against problems associated with increasing substrate content (quantitated as WIS, water-insoluble solids, in the range 12.5–17.5%), and was compared to the beneficial effect on the saccharification reaction achieved by increasing the enzyme preparation (Cellic CTec3) loadings. Aerated reactions were compared to reactions supplied with N2 to assess the contribution of LPMO to the saccharification reactions. Analysis using 13C NMR spectroscopy, XRD, Simons’ staining, BET analysis, and SEM analysis was used to gain further insights into the effects of the cellulolytic enzymes on the substrate under different reaction conditions.ResultsAlthough glucose production after 72 h was higher at 17.5% WIS than at 12.5% WIS, glucan conversion decreased with 24% (air) and 17% (N2). Compared to reactions with N2, the average increases in glucose production for aerated reactions were 91% (12.5% WIS), 70% (15.0% WIS), and 67% (17.5% WIS). Improvements in glucan conversion through aeration were larger (55–86%) than the negative effects of increasing WIS content. For reactions with 12.5% WIS, increased enzyme dosage with 50% improved glucan conversion with 25–30% for air and N2, whereas improvements with double enzyme dosage were 30% (N2) and 39% (air). Structural analyses of the solid fractions revealed that the enzymatic reaction, particularly with aeration, created increased surface area (BET analysis), increased disorder (SEM analysis), decreased crystallinity (XRD), and increased dye adsorption based on the cellulose content (Simons' staining).ConclusionsThe gains in glucan conversion with aeration were larger than the decreases observed due to increased substrate content, resulting in higher glucan conversion when using aeration at the highest WIS value than when using N2 at the lowest WIS value. The increase in glucan conversion with double enzyme preparation dosage was smaller than the increase achieved with aeration. The results demonstrate the potential in using proper aeration to exploit the inherent capacity of LPMO in enzymatic saccharification of lignocellulosic substrates and provide detailed information about the characteristics of the substrate after interaction with cellulolytic enzymes.

Improving photofermentative hydrogen productivity of photosynthetic bacteria using a formulated Fe and Mo metal supplemented lignocellulosic substrate

Strategy to improve single-stage photofermentative hydrogen productivity of photosynthetic bacteria (PSB) by efficient use a formulated lignocellulosic substrate through suitable supplement of iron and molybdenum as enhancers of microbial activity of R. palustris was proposed. The maximum hydrogen production rate of 48.1 ml h−1 L−1 was obtained using response surface methodology as the result of accelerated bioreaction of proton reduction under inoculum density of 118.1 mg L−1, Fe2+ of 13.2 mg L−1 and Mo6+ of 2.65 μg L−1. Biokinetic analysis revealed the enhanced microbial activities in biomass synthesis and H2 production. Suitable metal addition enabled PSB to act in whole as biocatalyst to facilitate assimilation of the formulated electron-rich carbon source from wheat straw through the efficient electron transfer needed for both cell growth and enzyme function of nitrogenase. Therefore, higher kinetic values of kc in 0.146 h−1 and Rm in 59.4 ml h−1 L−1, accompanied with improved performances of H2 yield in 1.56 mol mol−1 carbon and substrate degradation in 93.6% were attained.

Genome-wide analysis of the Pleurotus eryngii laccase gene (PeLac) family and functional identification of PeLac5

The laccase gene family encodes multiple isozymes that are crucial for the degradation of substrates and the regulation of developmental processes in fungi. Pleurotus eryngii is an important edible and medicinal fungus belonging to the Basidiomycota phylum and can grow on a variety of natural substrates. In the present study, genome-wide profiling of P. eryngii identified 10 genes encoding its laccase isoenzymes. Conservative sequence analysis demonstrated that all PeLacs possess classical laccase structural domains. Phylogenetic analysis yielded four major subgroups, the members of which are similar with respect to conserved gene organization, protein domain architecture, and consensus motifs. The 10 PeLacs formed three groups together with 12 PoLacs in Pleurotus ostreatus, indicating that they share a high level of evolutionary homology. Cis-responsive element analysis implied that PeLacs genes play a role in growth and development and lignocellulose degradation. Targeted overexpression of PeLac5 reduced the time to primordia formation and their development to fruiting bodies. Gene expression patterns in the presence of different lignocellulosic substrates indicate that three PeLacs genes (2, 4, and 9) are key to lignocellulose degradation. This work presents the first inventory of laccase genes in P. eryngii and preliminarily explores their functions, which may help to uncover the manner by which these proteins utilize substrates.

Taxonomic composition and carbohydrate-active enzyme content in microbial enrichments from pulp mill anaerobic granules after cultivation on lignocellulosic substrates

Metagenomes of lignocellulose-degrading microbial communities are reservoirs of carbohydrate-active enzymes relevant to biomass processing. Whereas several metagenomes of natural digestive systems have been sequenced, the current study analyses metagenomes originating from an industrial anaerobic digester that processes effluent from a cellulose pulp mill. Both 16S ribosomal DNA and metagenome sequences were obtained following anaerobic cultivation of the digester inoculum on cellulose and pretreated (steam exploded) poplar wood chips. The community composition and profile of predicted carbohydrate-active enzymes were then analyzed in detail. Recognized lignocellulose degraders were abundant in the resulting cultures, including populations belonging to Clostridiales and Bacteroidales orders. Poorly defined taxonomic lineages previously identified in other lignocellulose-degrading communities were also detected, including the uncultivated Firmicutes lineage OPB54 which represented nearly 10% of the cellulose-fed enrichment even though it was not detected in the bioreactor inoculum. In total, 3580 genes encoding carbohydrate-active enzymes were identified through metagenome sequencing. Similar to earlier enrichments of animal digestive systems, the profile encoded by the bioreactor inoculum following enrichment on pretreated wood was distinguished from the cellulose counterpart by a higher occurrence of enzymes predicted to act on pectin. The majority (> 93%) of carbohydrate-active enzymes predicted to act on plant polysaccharides were identified in the metagenome assembled genomes, permitting taxonomic assignment. The taxonomic assignment revealed that only a small selection of organisms directly participates in plant polysaccharide deconstruction and supports the rest of the community.

Acquisition, Characterization, and Optimization of Distilled Bioethanol Generated from Fermented Carrot (Daucus carota) Residues

Bioethanol is a liquid biofuel produced from the digestion of biomass and usable waste of organic origin. The objective of this research was to obtain bioethanol from carrot (Daucus carota) residues of the Peruvian Chantenay variety, with a high content of lignocellulosic substances. The in-batch process method of enzymatic hydrolysis, with Aspergillus niger amyloglucosidase, and fermentation, with Saccharomyces cerevisiae yeast, was applied. The ferment was steam distilled and chemically characterized. The process was evaluated by controlling pH and enzyme/yeast mass ratio through the response surface optimization. The optimum conditions for the best values of TSS and % ethanol content for the distilled product were a time of 300 min, yeast/enzyme mass ratio of 24.0, and pH of 4.98. The results showed a significant decrease in sugars in the hydrolysis and fermentation stages, optimum alcohol content in the distilled product of 92.48% (v/v), lower organic compound content, and net calorific value of 23.82 MJ/kg, which is higher than those reported in the literature.

High potential for biomass-degrading CAZymes revealed by pine forest soil metagenomics

The undisturbed environment in Netarhat, with its high levels of accumulated lignocellulosic biomass, presents an opportunity to identify microbes for biomass digestion. This study focuses on the bioprospecting of native soil microbes from the Netarhat forest in Jharkhand, India, with the potential for lignocellulosic substrate digestion. These biocatalysts could help overcome the bottleneck of biomass saccharification and reduce the overall cost of biofuel production, replacing harmful fossil fuels. The study used metagenomic analysis of pine forest soil via whole genome shotgun sequencing, revealing that most of the reads matched with the bacterial species, very low percentage of reads (0.1%) belongs to fungal species, with 13% of unclassified reads. Actinobacteria were found to be predominant among the bacterial species. MetaErg annotation identified 11,830 protein family genes and 2 metabolic marker genes in the soil samples. Based on the Carbohydrate Active EnZyme (CAZy) database, 3,996 carbohydrate enzyme families were identified, with family Glycosyl hydrolase (GH) dominating with 1,704 genes. Most observed GH families in the study were GH0, 3, 5, 6. 9, 12. 13, 15, 16, 39, 43, 57, and 97. Modelling analysis of a representative GH 43 gene suggested a strong affinity for cellulose than xylan. This study highlights the lignocellulosic digestion potential of the native microfauna of the lesser-known pine forest of Netarhat. Communicated by Ramaswamy H. Sarma

Ruminal content biochar supplementation for enhanced biomethanation of rice straw: Focusing on biochar characterization and dose optimization

Anaerobic digestion (AD) of agricultural wastes is a promising approach for energy recovery and crop residue management. However, its recalcitrant chemical structure hinders microbial hydrolysis and reduces biomethane production under AD. Biochar supplementation has been proven to promote the digestibility and biomethanation of lignocellulosic substrates. Therefore, this study investigated the influence of different pyrolysis temperatures (450 °C, 550 °C, and 650 °C) on the physicochemical properties of biochar. Furthermore, the impact of ruminal content biochar supplementation (1 %, 2 %, and 3 %) on the AD of rice straw with rumen fluid as inoculum has been investigated. The ruminal content biochar (RUCB) supplemented reactors showed an increment in biomethane yield and the highest cumulative biomethane yield 243.11 mL/g volatile solids (VS)) was recorded at 2 % RUCB supplementation, followed by 227.12 mL/g VS at 1 % RUCB supplementation and 162.86 mL/g VS at 3 % RUCB supplementation (P > 0.05). Compared to the control reactors (128.68 mL/g VS), RUCB supplemented reactors exhibited 1.88-fold, 1.76-fold, and 1.26-fold increments in biomethane yield due to pH stabilization and facilitation of microbial biofilm formation on the biochar. The correlation analysis showed that biomethane production is positively correlated with VS reduction (R2 = 0.9852). This study proposed a potential strategy to utilize ruminal content waste as a feedstock for biochar production and its application in AD for accelerating the biomethanation of rice straw.

Biobased lignin-blockers enable efficient production of glucose from lignocelluloses

Enzymatic hydrolysis of cellulose in lignocelluloses exhibits low efficiency due to low cellulose accessibility and adverse lignin effects. By using phenylsulfonic acid pretreatment to improve cellulose accessibility, we have developed several new plant proteins such as corn germ and green rapeseed proteins that extracted from inexpensive defatted meals as lignin-blockers. For pretreated lignocellulosic substrates with high cellulose accessibility, such plant proteins could effectively overcome negative lignin effects and achieve robust cellulose enzymatic conversion (88–97 %) at a low cellulase loading of 5 FPU/g glucan. To reach the same level of cellulose enzymatic conversion, adding corn germ protein could save cellulase loading by 3.6 times as compared to those without lignin-blockers. But these plant proteins showed insignificant promotion effects on substrates with low cellulose accessibility. Overall, this study coupled high cellulose-accessible substrates and efficient lignin-blockers to synergistically improve the profitability of lignocellulosic biorefinery.

Improved secretory expression and characterization of thermostable xylanase and β-xylosidase from Pseudothermotoga thermarum and their application in synergistic degradation of lignocellulose.

Xylanase and β-xylosidase are the key enzymes for hemicellulose hydrolysis. To further improve hydrolysis efficacy, high temperature hydrolysis with thermostable hemicellulases showed promise. In this study, thermostable xylanase (Xyn) and β-xylosidase (XynB) genes from Pseudothermotoga thermarum were cloned and secretory expressed in Bacillu subtilis. Compared with Escherichia coli expression host, B. subtilis resulted in a 1.5 time increase of enzymatic activity for both recombinant enzymes. The optimal temperature and pH were 95°C and 6.5 for Xyn, and 95°C and 6.0 for XynB. Thermostability of both recombinant enzymes was observed between the temperature range of 75-85°C. Molecular docking analysis through AutoDock showed the involvement of Glu525, Asn526, Trp774 and Arg784 in Xyn-ligand interaction, and Val237, Lys238, Val761 and Asn76 in XynB-ligand interaction, respectively. The recombinant Xyn and XynB exhibited synergistic hydrolysis of beechwood xylan and pretreated lignocellulose, where Xyn and XynB pre-hydrolysis achieved a better improvement of pretreated lignocellulose hydrolysis by commercial cellulase. The observed stability of the enzymes at high temperature and the synergistic effect on lignocellulosic substrates suggested possible application of these enzymes in the field of saccharification process.

A new paradigm in lignocellulolytic enzyme cocktail optimization: Free from expert-level prior knowledge and experimental datasets

Effectively pairing diverse lignocellulolytic enzyme cocktails with intricately structured lignocellulosic substrates is an enduring challenge for science and technology. To date, extensive trial-and-error remains the primary approach and no deep-learning methods were developed to address it due to limited experimental data and incomplete expert-level knowledge of enzyme-cocktail-substrate structure-dynamics-function relationships. Here, a novel model is developed to tackle this issue in efficient, cost-effective, and high-throughput manners. It needs no pre-labeled datasets, instead utilizing simple features, eliminating the reliance on expert-level prior knowledge of reaction mechanisms. Experimentally optimal combinations were found within predicted ranges of tailor-made combinations with precision of 91.98%, covering 80.00% of overall top-100. Practical tests demonstrated its effectiveness in narrowing down potential optimal combinations, speeding up targeted screening, and enabling efficient degradation of lignocellulosic biomass. The method has good applications in artificial proteins biosynthesis from low-value lignocellulosic straw, providing alternative solutions for biomass biorefining challenges in complex enzyme-cocktail-substrate interactions.

Biological treatment as a green approach for enhancing electrochemical performance of wood derived carbon based supercapacitor electrodes

Wood-derived biochar is an eco-friendly and porous carbon material that can be used to prepare supercapacitor electrodes. For the purpose of addressing the deficiencies in the specific surface area and pore structure of wood-derived carbon as the raw material of electrodes, a biological pre-treatment method was developed to construct the desirable pore structure of wood by leveraging the lignin-degrading property of white-rot fungi. First, white-rot fungi with permeability and biodegradability on lignocellulosic substrates were used to regulate the pore structure of natural paulownia wood, which was then carbonized to produce a porous hyphae/wood-derived carbon conductive substrate. Afterward, manganese dioxide (MnO2) was deposited on the substrate to fabricate the MnO2/hyphae/wood-derived carbon (HWC-3M) electrode by the hydrothermal method. The degradation of lignin by white-rot fungi broke the original pore structure of wood, strengthened effective channels in the cell walls, and facilitated the loading of MnO2 into the channels to improve the ion transport rate. The HWC-3M had richer energy storage sites, more electrolyte ion transport channels, and better electrochemical performance than the control electrode made of untreated wood-derived carbon (HWC-0), showing an excellent areal specific capacitance (3395 mF/cm2 at a current density of 1.0 mA/cm2), moderate gravimetric specific capacitance (138.3 F/g), and good cycling stability (retention of 88.6% after 2000 cycles). The results indicate that pretreating wood-derived carbon composite electrode with white-rot fungi serves as a new green approach to develop high-performance electrochemical energy storage devices.

Characterization of lignin and hemicellulose degrading bacteria isolated from cow rumen and forest soil: Unveiling a novel enzymatic model for rice straw deconstruction

Application of greener pretreatment technology using robust ligninolytic bacteria for short duration to deconstruct rice straw and enhance bioethanol production is currently lacking. The objective of this study is to characterize three bacterial strains isolated from the milieux of cow rumen and forest soil and explore their capabilities of breaking down lignocellulose – an essential process in bioethanol production. Using biochemical and genomic analyses these strains were identified as Bacillus sp. HSTU-bmb18, Bacillus sp. HSTU-bmb19, and Citrobacter sp. HSTU-bmb20. Genomic analysis of the strains unveiled validated model hemicellulases, multicopper oxidases, and pectate lyases. These enzymes exhibited interactions with distinct lignocellulose substrates, further affirmed by their stability in molecular dynamic simulations. A comprehensive expression of ligninolytic pathways, including β-ketoadipate, phenyl acetate, and benzoate, was observed within the HSTU-bmb20 genome. The strains secreted approximately 75–82 U/mL of cellulase, xylase, pectinase, and lignin peroxidase. FT-IR analysis of the bacterial treated rice straw fibers revealed that the intensity of lignin-related peaks decreased, while cellulose-related peaks sharpened. The values of crystallinity index for the untreated control and the treated rice straw with either HSTU-bmb18, or HSTU-bmb19, or HSTU-bmb20 were recorded to be 34.48, 28.49, 29.36, 31.75, respectively, which are much higher than that of 13.53 noted for those treated with the bacterial consortium. The ratio of fermentable cellulose in rice straw increased by 1.25-, 1.79-, 1.93- and 2.17-fold following treatments with HSTU-bmb18, HSTU-bmb20, HSTU-bmb19, and a mixed consortium of these three strains, respectively. These aggregative results suggested a novel model for rice straw deconstruction utilizing hydrolytic enzymes of the consortium, revealing superior efficacy compared to individual strains, and advancing cost-effective, affordable, and sustainable green technology.

Anaerobic mono and co-digestion of agro-industrial waste and municipal sewage sludge: Biogas production potential, kinetic modelling, and digestate characteristics

Lignocellulosic substrates, including wastes generated from agro-industrial activities, are bio-residues evaluated to put an end to the energy needs and sustainable waste disposal problems that the world is trying to deal with today. However, the slow rate of hydrolysis of such lignocellulosic wastes limits the biogas production efficiency with the mono-anaerobic digestion (AD) process. Therefore, anaerobic co-digestion (AnCoD) of such wastes with secondary raw materials rich in microorganisms and various nutrients, such as sewage sludge, is an economical and useful method for both enhancing biogas production and disposal of more waste. In this study, AD and AnCoD processes for biogas and methane production were investigated on okra waste (OW) and municipal sewage sludge (MSS) by using cattle manure as inoculation, which constitutes only 8% of the total working volume. Five different substrate mixing ratios (100%OW, 75%OW-25%MSS, 50%OW-50%MSS, 25%OW-75%MSS, and 100MSS%) were prepared to observe the effect of C/N ratio, maximum biogas production potential, methane content, and organic matter removal efficiency on AD and AnCoD processes. All bioreactors were operated in a batch process with 8% TS in mesophilic temperature for 25 days. The amount of biogas produced in the 100%OW experimental set for the AD process was 44% more than 100%MSS. However, the AnCoD process was more efficient than AD, and biogas and methane production increased by up to 66% and 112%, respectively, compared to the mono-substrate experimental set. The highest biogas production value was 1060 mL (375 mL/gVSremoved) with 60% methane content in the bioreactor consisting of 25%OW-75%MSS. As a result of AD and AnCoD process, soluble carbohydrate, protein and COD removal for all bioreactors were between 62% and 79%, 28%-68% and 54%-70%, respectively. The FT-IR peaks seen in digestates were consistent with the presence of functional groups formed as a result of AnCoD. Monod, Cone, Transference function, and Logistic function kinetic models were used for the estimation of cumulative biogas production efficiency. In addition, the energy potential of the methane produced as a result of the AD and AnCoD processes and the financial gain that can be obtained from its direct sale were evaluated.

Efficient Biorefinery Based on Designed Lignocellulosic Substrate for Lactic Acid Production

The current study investigated the feasibility of developing and adopting a few state-of-the-art fermentation techniques to maximize the efficiency of the lignocellulosic waste bioconversion. There have been various efforts towards utilizing the fermentable sugars released from the specific parts of lignocellulose, i.e., cellulose and hemicellulose. However, complete utilization of carbon sources derived from lignocellulosic biomass remains challenging owing to the generated glucose in the presence of β-glucosidase, which is known as glucose-induced carbon catabolite repression (CCR). To overcome this obstacle, a novel simultaneous saccharification and fermentation (SSF) of lactic acid was designed by using Celluclast 1.5L as a hydrolytic enzyme to optimize the generation and utilization of pentose and hexose. Under the optimal enzyme loading and pH condition, 53.1 g/L optically pure L-lactic acid with a maximum volumetric productivity of 3.65 g/L/h was achieved during the SSF from the brewer’s spent grain without any nutrient supplementation. This study demonstrated the potential of lactic acid production from the designed lignocellulosic substrate.

Brackish Groundwaters Contain Plastic- and Cellulose-Degrading Bacteria.

The selected brackish groundwater occurrences in the geotectonic regions of Inner Dinarides of western Serbia (Obrenovačka Banja) and Serbian crystalline core (Lomnički Kiseljak and Velika Vrbnica) were sampled for isolation and identification of plastic- and lignocellulose-degrading bacteria, as well as for the assessment of their enzymatic potential. The examined occurrences belong to the cold and warm (subthermal), weakly alkaline, neutral, and weakly acidic groundwater, and their genetic types are HCO3-Na + K and HCO3-Ca, Mg. The most abundant genera identified by next-generation 16S sequencing of cultivated groundwater samples belong to Aeromonas and Exiguobacterium. Of isolates screened on plastic and lignocellulosic substrates, 85.3% demonstrated growth and/or degrading activity on at least one tested substrate, with 27.8% isolates degrading plastic substrate Impranil® DLN-SD (SD), 1.9% plastic substrate bis(2-hydroxyethyl)terephthalate, and 5.6% carboxymethyl cellulose (CMC). Isolates degrading SD that were identified by 16S rDNA sequencing belonged to genera Stenotrophomonas, Flavobacterium, Pantoea, Enterobacter, Pseudomonas, Serratia, Acinetobacter, and Proteus, while isolates degrading CMC belonged to genera Rhizobium and Shewanella. All investigated brackish groundwaters harbor bacteria with potential in degradation of plastics or cellulose. Taking into account that microplastics contamination of groundwater resources is becoming a significant problem, the finding of plastic-degrading bacteria may have potential in bioremediation treatments of polluted groundwater. Subterranean ecosystems, which are largely untapped resources of biotechnologically relevant enzymes, are not traditionally considered the environment of choice for screening for plastic- and cellulose-degrading bacteria and therefore deserve a special attention from this aspect.

Bioacetoin Production by Bacillus subtilis subsp. subtilis Using Enzymatic Hydrolysate of Lignocellulosic Biomass

Acetoin is an important bio-product useful in the chemical, food and pharmaceutical industries. Microbial fermentation is the major process for the production of bioacetoin, as the petroleum resources used in chemical methods are depleting day by day. Bioacetoin production using wild microorganisms is an easy, eco-friendly and economical method for the production of bioacetoin. In the present study, culture conditions and nutritional requirements were optimized for bioacetoin production by a wild and non-pathogenic strain of B. subtilis subsp. subtilis JJBS250. The bacterial culture produced maximum bioacetoin (259 mg L−1) using peptone (3%) and sucrose (2%) at 30 °C, 150 rpm and pH 7.0 after 24 h. Further supplementation of combinatorial nitrogen sources, i.e., peptone (1%) and urea (0.5%), resulted in enhanced titre of bioacetoin (1017 mg L−1) by the bacterial culture. An approximately 46.22–fold improvement in bioacetoin production was achieved after the optimization process. The analysis of samples using thin layer chromatography confirmed the presence of bioacetoin in the culture filtrate. The enzymatic hydrolysate was obtained by saccharification of pretreated rice straw and sugarcane bagasse using cellulase from Myceliophthora thermophila. Fermentation of the enzymatic hydrolysate (3%) of pretreated rice straw and sugarcane bagasse by the bacterial culture resulted in 210 and 473.17 mgL−1 bioacetoin, respectively. Enzymatic hydrolysates supplemented with peptone as a nitrogen source showed a two to four-fold improvement in the production of bioacetoin. Results have demonstrated the utility of wild type B. subtilis subsp. subtilis JJBS250 as a potential source for economical bioacetoin production by making use of renewable and cost-effective lignocellulosic substrate. Therefore, this study will help in the sustainable management of agricultural waste for the industrial production of bioacetoin, and in combating environmental pollution.

Biofuel Production from Mango and Orange Peel and Tapioca Shells by Fermentation Using Consortium of Bacteria: Agricultural and Food Waste Valorization

Lignocellulosic substrates are considered to be crucial substrates for the production of biofuels. The main objective of the study is to attempt to produce bioethanol using bio-wastes such as mango peels, orange peels, and tapioca shells as renewable sources by employing three bacteria viz., Enterobacter cloacae (ICBP1), Pseudomonas aeruginosa (ICBP7), and Bacillus cereus (ICBP15), which were chosen to produce cellulase enzymes using the submerged fermentation method, which is a novel method for the production of bioethanol. The “zone of clearance” in bacterial growth on CMC agar plates determined the choice. The mixed culture infected units produced a more reduced sugar, i.e., the presence of aldehyde and ketones except sucrose. At 72 h, greater than 41.0 ± 0.48 mL and 0.83 ± 0.07% of ethanol was recovered. This contrasts with the reduced quantities at 24 and 48 h. SDS-PAGE examination showed that the three cellulose-producing bacterial strains (ICPB1, ICPB7, and ICPB15) had enzyme molecular weights of 80–100, 20–30, and 14–20 kDa, respectively, compared to the other 17 isolates. Fourier-transform infrared (FTIR) spectroscopy was used to estimate the bioethanol. The spectrum bands from 1700 to 1800 cm−1 showed bioethanol’s unique absorption characteristics, and GC-MS confirmed 31.38% ethanol. The findings of the research demonstrate that the utilization of fermentation technology, specifically employing microbes, to produce bioethanol from bio-wastes such as fruits and vegetables has the potential to address the worldwide fuel energy requirements.

Application of solid-state fermentation using mushrooms for the production of animal feed.

The increasing growth of agroindustrial activity resulting in excessive amounts of agriwaste has led to the accumulation of a large quantity of lignocellulosic residues all over the world, in particular in deforestation initiatives for the removal of invasive trees in South Africa. These lignocellulosic residues are rich in energy resources and consist of a mixture of natural polymers based on lignin, cellulose, and hemicellulose. The use of lignolytic fungi such as mushrooms in solid-state fermentation could sufficiently degrade the indigestible lignocellulosic components and add medicinal and nutritional value to otherwise unusable, high-energy waste material, which in turn could yield a new method of producing energy-rich fodder for ruminant animals. The digestive type of animal for which the potential feed is developed must be identified and considered before deciding on the bioconversion method and process, as the outcomes for obtaining potentially high-quality feeds for nonruminant and ruminant animals are different. The current study presents data on the bioconversion of lignocellulosic substrate using solid-state fermentation with edible and medicinal mushrooms, Ganoderma lucidumand Pleurotus ostreatus, and a possible new species, to increase digestibility and nutritional value to be applied as ruminant animal feed. The solid-state fermentation process was optimized and the resulting product was analyzed for the degradation of the lignocellulosic components. Results indicated that the solid-state fermentation duration and mushroom species were key components in achieving significant degradation. Data obtained after 18 weeks of degradation indicated a significant (p < 0.05) reduction in the acid detergent fiber, acid detergent lignin, and neutral detergent fiber fractions of the biomass, with up to a 20% reduction in indigestible components. This increase in digestibility could contribute to increased energy availability for ruminant animals.

Comparison of the Effects of Pulsed Electric Field Disintegration and Ultrasound Treatment on the Efficiency of Biogas Production from Chicken Manure

This study used chicken manure classified as lignocellulosic biomass due to its high straw content. This paper compares the possibility of using pulsed electric field (PEF) pretreatment of lignocellulosic substrates with ultrasonic disintegration (UP) to increase methane production. As for ultrasonic treatment, the BMP increased from 210.42 ± 7.92 mL/g VS to 250.06 ± 8.68 mL/g VS, whereas with PEF disintegration, the BMP ratio increased from 210.42 ± 7.92 mL/g VS to 248.90 ± 9.29 mL/g VS. The use of PEF and UP pretreatment increased methane production from 307.29 ± 13.65 mL/g VS to 366.99 ± 14.18 mL/g VS and from 307.29 ± 13.65 mL/g VS to 365.07 ± 11.71 mL/g VS, respectively. This study showed that both ultrasonic treatment and PEF contribute to the biochemical potential of methane (BMP) from chicken manure.