Optimization and purification of laccase activity from Mammaliicoccus sciuri isolated from the soils of Similipal, Odisha, India: a kinetics study of crystal violet dye decolorization.

Four laccase-producing bacteria were found in soil samples from the Similipal Biosphere Reserve in Odisha, according to the current study. The isolates (SLCB1 to SLCB4) were evaluated for their laccase-producing ability in LB broth supplemented with guaiacol. The ABTS assay was performed to assess the laccase activity. The bacterium Mammaliicoccus sciuri shows the highest laccase activity i.e., 0.5125 U/L at the optimized conditions of pH 5.5, temperature 32.5 °C, ABTS concentration of 0.75 µl with an incubation time of 9 d. Laccase activity of M. sciuri grown in Sawdust was significantly increased in comparison to that in other agro wastes. The partially purified laccase enzyme after ammonium sulfate precipitation and dialysis showed a molecular weight of ∼58.5 kDa as determined by SDS-PAGE. A decolorization efficiency of 66.67% was recorded for the dye crystal violet after 1 h treatment with dialyzed laccase enzyme compared with phenol red, brilliant blue, and methylene blue.

Recent updates on green synthesis of lignin nanoparticle and its potential applications in modern biotechnology.

Lignin is a complex of organic polymers that are abundantly present in the plant cell wall which considered of emerging substrates for various kinds of value-added industrial products. Lignin has potential use for the production of green nanomaterials, which exhibit improved or different properties corresponding to their parent polymers. Nano lignin has received significant interest in recent years due to its applications in numerous fields. Lignin, the abundant and limited functionality has challenges for its potential uses. Creating advanced functional lignin-derived material like lignin nanoparticles (LNPs) which significantly alter the biological process has great potential for its applications. In the fields of biotechnology, several lignin extraction processes from various raw materials and diverse synthesis techniques, including acid precipitation, dialysis, solvent shifting/solvent exchange, antisolvent precipitation, homogenization, water-in-oil (W/O) microemulsion, ultra-sonication, interfacial crosslinking, polymerization, and biological pathway can be employed to produce LNPs. The scientific community has recently become more concerned about the transformation of lignin to lignin nanomaterials, including nanoparticles, nanocapsules, nanofibers, nanotubes, and nanofilms. Recent research has shown that lignin nanoparticles (LNPs) are: non-toxic at adequate amounts (both in vitro and in vivo), are economical, and can be biodegradable by bacteria and fungi. In promising studies, LNPs have been investigated for their potential applications in gene delivery systems, drug carriers, biocatalysts, tissue engineering, heavy metal absorbers, encapsulation of molecules, supercapacitors, hybrid nanocomposites, and other applications. This current review addresses the recent advances in the synthesis of LNPs, their advanced application in different areas, future perspectives, and challenges associated with lignin-based nanomaterials.

Purified cellulase-mediated simultaneous sugar utilization by Bacillus albus isolated from Similipal, Odisha, India.

Among 24 isolated cellulolytic bacteria from Similipal Biosphere Reserve, the most efficient isolate was recognized as a strain of Bacillus albus. This strain of B. albus was evaluated for cellulase production and the cellulase activity was measured in submerged fermentation using substrate carboxymethyl cellulose (CMC). Different nutritional (carbon, nitrogen, and metal-ion sources) and physical variables (pH, temperature, substrate concentration, and incubation time) during the growth of B. albus were optimized to obtain maximum cellulase activity. The highest cellulase activity of 5.79 U/mL for B. albus was observed at pH 6.75, temperature 37.5°C, CMC concentration 8.5 g/L, and 42 h incubation time. Further, supplementation of glucose as a subsidiary carbon source, yeast extract, peptone as nitrogen sources, and MgSO4 and MnSO4 as metal-ion sources enhance the cellulase activity of B. albus. The purified enzyme was reported to have a molecular weight of ∼54 kDa as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A zymogram analysis evidenced the cellulase activity of the purified enzyme fractions obtained from diethylaminoethyl cellulose chromatography. The purified cellulase was reported to have an optimum pH and temperature of 7.0°C and 50°C, respectively with a capacity of retaining its 60% residual activity within pH 6.0-8.0 and temperature 30-40°C, respectively. The metal ions, K+ and Na+ were the activators, while Pb2+ and Hg2+ were the inhibitors for the purified cellulase. The purified cellulase showed Km and Vmax values of 0.38 M and 8.19 U/mL, respectively, in presence of the substrate CMC and also simultaneous consumption of both hexose and pentose sugars.

Optimisation of Manganese Peroxidase (MnP) Activity of Enterobacter wuhouensis Using Response Surface Method and Evaluation of Its Maillard Reaction Products Along with Lignin Degradation Ability.

Manganese peroxidase (MnP), a microbial ligninolytic enzyme which plays significant role in lignin and melanoidin degradation has gained much attention in the field of industry. In the present study, 15 ligninolytic bacteria were isolated from the soil sample of Similipal Biosphere Reserve (SBR) and screened for MnP activity. The most efficient MnP-producing bacterium HNB5 was evaluated for alkali lignin and maillard reaction products (MRPs) degradation and identified as Enterobacter wuhouensis using 16S rRNA sequencing. This bacterium exhibited the highest MnP activity of 2.6 U mL-1 min-1 in un-optimized conditions. Further, optimization using response surface methodology E. wuhouensis showed increased MnP activity of 4.11 U mL-1 min-1 at pH 6.3, temperature 37 °C, substrate concentration 1.05%, and time 144 h. In both FT-IR and UV-Vis spectrophotometry analyses of control and bacterium degraded MRPs, the reduction in Maillard product colour was correlated with shifting absorption peaks. Also, the GC-MS analysis data showing a change in functional group revealed the rise of novel peaks caused due to the degradation of MRPs complex. The phytotoxicity study was conducted for bacterial degraded MRPs medium revealed that toxicity of the medium decreased after bacterial treatment. The findings of the current study suggest that the manganese MnP produced by E. wuhouensis isolated from SBR soil sample may be employed for bioremediation purposes to degrade MRPs.

Functional diversity and metabolic profile of microbial community of mine soils with different levels of chromium contamination.

Microbial communities provide useful information about any chemical and physical changes in the environment and play an essential role in maintaining soil fertility. Biolog® eco-plates method was used to study the functional diversity of microbial communities, and their correlation with soil organic carbon (OC), microbial biomass and activities, under three different soil conditions of Sukinda chromite mining area of Odisha, India during August 2016. The OC, available nitrogen, available phosphorus and available potash were significantly (p < 0.05) lower in in situ and overburden soils as compared to forest soil. The average development rate of average well color development values decreased with incubation time in all soil conditions. The utilization of six categories of carbon sources by soil microbes decreased with the increase in chromium load and biplot analysis suggested that carbohydrate, polymer and amino acid utilizing microbes were dominant in mining soils. The ecotoxicological status of chromite mine soil would be useful for formulating strategies of possible bioremediation program.

Insights into the mode of flavin mononucleotide binding and catalytic mechanism of bacterial chromate reductases: A molecular dynamics simulation study.

Enzymes from natural sources protect the environment via complex biological mechanisms, which aid in reductive immobilization of toxic metals including chromium. Nevertheless, progress was being made in elucidating high-resolution crystal structures of reductases and their binding with flavin mononucleotide (FMN) to understand the underlying mechanism of chromate reduction. Therefore, herein, we employed molecular dynamics (MD) simulations, principal component analysis (PCA), and binding free energy calculations to understand the dynamics behavior of these enzymes with FMN. Six representative chromate reductases in monomeric and dimeric forms were selected to study the mode, dynamics, and energetic component that drive the FMN binding process. As evidenced by MD simulation, FMN prefers to bind the cervix formed between the catalytic domain surrounded by strong conserved hydrogen bonding, electrostatic, and hydrophobic contacts. The slight movement and reorientation of FMN resulted in breakage of some crucial H-bonds and other nonbonded contacts, which were well compensated with newly formed H-bonds, electrostatic, and hydrophobic interactions. The critical residues aiding in tight anchoring of FMN within dimer were found to be strongly conserved in the bacterial system. The molecular mechanics combined with the Poisson-Boltzmann surface area binding free energy of the monomer portrayed that the van der Waals and electrostatic energy contribute significantly to the total free energy, where, the polar solvation energy opposes the binding of FMN. The proposed proximity relationships between enzyme and FMN binding site presented in this study will open up better avenues to engineer enzymes with optimized chromate reductase activity for sustainable bioremediation of heavy metals.

Engineering grass biomass for sustainable and enhanced bioethanol production.

MAIN CONCLUSION: Bioethanol from lignocellulosic biomass is a promising step for the future energy requirements. Grass is a potential lignocellulosic biomass which can be utilised for biorefinery-based bioethanol production. Grass biomass is a suitable feedstock for bioethanol production due to its all the year around production, requirement of less fertile land and noninterference with food system. However, the processes involved, i.e. pretreatment, enzymatic hydrolysis and fermentation for bioethanol production from grass biomass, are both time consuming and costly. Developing the grass biomass in planta for enhanced bioethanol production is a promising step for maximum utilisation of this valuable feedstock and, thus, is the focus of the present review. Modern breeding techniques and transgenic processes are attractive methods which can be utilised for development of the feedstock. However, the outcomes are not always predictable and the time period required for obtaining a robust variety is generation dependent. Sophisticated genome editing technologies such as synthetic genetic circuits (SGC) or clustered regularly interspaced short palindromic repeats (CRISPR) systems are advantageous for induction of desired traits/heritable mutations in a foreseeable genome location in the 1st mutant generation. Although, its application in grass biomass for bioethanol is limited, these sophisticated techniques are anticipated to exhibit more flexibility in engineering the expression pattern for qualitative and qualitative traits. Nevertheless, the fundamentals rendered by the genetics of the transgenic crops will remain the basis of such developments for obtaining biorefinery-based bioethanol concepts from grass biomass. Grasses which are abundant and widespread in nature epitomise attractive lignocellulosic feedstocks for bioethanol production. The complexity offered by the grass cell wall in terms of lignin recalcitrance and its binding to polysaccharides forms a barricade for its commercialization as a biofuel feedstock. Inspired by the possibilities for rewiring the genetic makeup of grass biomass for reduced lignin and lignin-polysaccharide linkages along with increase in carbohydrates, innovative approaches for in planta modifications are forging ahead. In this review, we highlight the progress made in the field of transgenic grasses for bioethanol production and focus our understanding on improvements of simple breeding techniques and post-harvest techniques for development in shortening of lignin-carbohydrate and carbohydrate-carbohydrate linkages. Further, we discuss about the designer lignins which are aimed for qualitable lignins and also emphasise on remodelling of polysaccharides and mixed-linkage glucans for enhancing carbohydrate content and in planta saccharification efficiency. As a final point, we discuss the role of synthetic genetic circuits and CRISPR systems in targeted improvement of cell wall components without compromising the plant growth and health. It is anticipated that this review can provide a rational approach towards a better understanding of application of in planta genetic engineering aspects for designing synthetic genetic circuits which can promote grass feedstocks for biorefinery-based bioethanol concepts.

Active and passive biosorption of Pb(II)using live and dead biomass of marine bacterium Bacillus xiamenensis PbRPSD202: Kinetics and isotherm studies.

A highly lead(II) resistant (up to 2200 mg/l) bacterium PbRPSD202 was selected among 210 lead resistant bacteria isolated from marine environment of Paradeep Port, Odisha for possible biosoption of toxic Pb (II) ions from metals polluted environments. The bacterium was identified as Bacillus xiamenensis following the phenotypic as well as 16S rRNA gene sequence analysis. In addition to Pb(II), it also showed resistance towards other heavy metals like Cd(II), Cr(VI), As(III), Cu(II), Ni(II) and Zn(II). Batch biosorption of Pb(II) using both live and dead biomass of this strain was investigated under different operational parametric conditions such as pH, temperature, NaCl concentration, shaking speed, treatment time, biomass concentration and initial Pb(II) concentration. The maximum Pb(II) uptake of 216.75 and 207.4 mg/g biomass was obtained with live and dead biomass, respectively, at the optimum condition (4% w/v NaCl, pH 6.0, 35 °C, 140 rpm and 1 g/l biosorbent dose). Both active as well as passive Pb(II) bio-sorption process showed best fit with the pseudo-second-order kinetic model. The sorption mechanism was favoured with Langmuir isotherm model indicating monolayer type adsorption. FTIR and FESEM-EDX analysis further ensured the possible interactions of Pb(II) with bacterial cell surface ligands like hydroxyl, carbonyl, carboxyl and amine groups during surface adsorption. TEM analysis revealed the intracellular accumulation of lead ions. This investigation highlights the potential application of this bacterium for bioremediation of lead(II) from the multiple metals contaminated saline environment through biosorption.

Physicochemical characterization, modelling and optimization of ultrasono-assisted acid pretreatment of two Pennisetum sp. using Taguchi and artificial neural networking for enhanced delignification.

Acid as well as ultrasono-assisted acid pretreatment of lignocellulosic biomass of two Pennisetum sp.; Denanath grass (DG) and Hybrid Napier grass (HNG) have been investigated for enhanced delignification and maximum exposure of cellulose for production of bioethanol. Screening of pretreatment with different acids such as H2SO4, HCl, H3PO4 and H2NO3 were optimized for different temperature, soaking time and acid concentrations using Taguchi orthogonal array and the data obtained were statistically validated using artificial neural networking. HCl was found to be the most effective acid for pretreatment of both the Pennisetum sp. The optimized conditions of HCl pretreatment were acid concentration of 1% and 1.5%, soaking time 130 and 50 min and temperature 121 °C and 110 °C which yielded maximum delignification of 33.0% and 33.8% for DG and HNG respectively. Further ultrosono-assisted HCl pretreatment with a power supply of 100 W, temperature of 353 K, and duty cycle of 70% has resulted in significantly higher delignification of 80.4% and 82.1% for both DG and HNG respectively than that of acid pretreatment. Investigation using SEM, FTIR and autofloresence microscopy for both acid and ultrasono-assisted acid pretreatment lignocellulosic biomass revealed conformational changes of pretreated lignocellulosic biomass with decreased lignin content and increased exposure of cellulose, with greater effectiveness in case of ultrasono assisted acid pretreatment condition.

Bacterial chromate reductase, a potential enzyme for bioremediation of hexavalent chromium: a review.

Hexavalent chromium is mobile, highly toxic and considered as a priority environmental pollutant. Chromate reductases, found in chromium resistant bacteria are known to catalyse the reduction of Cr(VI) to Cr(III) and have recently received particular attention for their potential use in bioremediation process. Different chromate reductases such as ChrR, YieF, NemA and LpDH, have been identified from bacterial sources which are located either in soluble fractions (cytoplasm) or bound to the membrane of the bacterial cell. The reducing conditions under which these enzymes are functional can either be aerobic or anaerobic or sometimes both. Enzymatic reduction of Cr(VI) to Cr(III) involves transfer of electrons from electron donors like NAD(P)H to Cr(VI) and simultaneous generation of reactive oxygen species (ROS). Based on the steps involved in electron transfer to Cr(VI) and the subsequent amount of ROS generated, two reaction mechanisms, namely, Class I "tight" and Class II "semi tight" have been proposed. The present review discusses on the types of chromate reductases found in different bacteria, their mode of action and potential applications in bioremediation of hexavalent chromium both under free and immobilize conditions. Besides, techniques used in characterization of the Cr (VI) reduced products were also discussed.

Organic acid-fractionated lignin silver nanoparticles: Antimicrobial, anticancer, and antioxidant characteristics.

Bioactive substances are utilized to treat a variety of diseases. Green lignin-mediated silver nanoparticles (L-Ag-NPs) have significant promise as a building block in the production of bio-renovation materials. The work optimized organic acid extraction to remove lignin from residual fermented hybrid Napier grass byproducts. We subsequently produced L-Ag-NPs. FTIR, XRD, DLS, and STEM characterized the sample. L-Ag-NPs were tested for antioxidant activity with the DPPH, DMPD, FRAP, and ABTS assays, as well as antibacterial activities. Antimicrobial activity was evaluated using four pathogenic bacteria (Klebsiella pneumonia, Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli). In contrast, cytotoxicity and ROS production assays were carried out using the HeLa cell line. The findings showed that L-Ag-NPs had high antioxidant efficiency. For each bacteria isolate, the antimicrobial activity showed favorable growth inhibition, with significant variations in L-Ag-NPs. L-Ag-NPs were reported to have an IC50 of 43.61 g/mL in the cytotoxicity test, and a significant increase in ROS generation was seen. In conclusion, L-Ag NPs have an excellent prospect in the pharmaceutical and biomedical industries and can be a dependable and environmentally safe material for their potential use.

Potentiality of bioactive compounds as inhibitor of M protein and F protein function of human respiratory syncytial virus.

The human respiratory syncytial virus (RSV) creates a pandemic every year in several countries in the world. Lack of target therapeutics and absence of vaccines have prompted scientists to create novel vaccines or small chemical treatments against RSV's numerous targets. The matrix (M) protein and fusion (F) glycoprotein of RSV are well characterized and attractive drug targets. Five bioactive compounds from Alnus japonica (Thunb.) Steud. were taken into consideration as lead compounds. Drug-likeness characters of them showed the drugs are non-toxic and non-mutagenic and mostly lipophobic. Molecular docking reveals that all bioactive compounds have better binding and better inhibitory effect than ribavirin which is currently used against RSV. Praecoxin A appeared as the best lead compound between them. It creates 7 different types of bonds with amino acids of M protein and 5 different types of bonds with amino acids of F protein. Van der Waals interactions highly influenced the binding energies. Molecular dynamic simulations represent the non-deviated and less fluctuating nature of praecoxin A. Principal Component Analysis showed praecoxin A complex with RSV matrix protein is more stable than ribavirin complex. This study will help to develop a new drug to inhibit RSV. All ligands were minimized through semi-empirical PM3 process with MOPAC. Toxicity was tested by ProTox-II server. Molecular docking studies were carried out using AutoDock 4.2. Molecular dynamics simulations for 100 ns were carried out through GROMACS 5.12 MD and GROMOS96 43a1 force field. The graphs were produced by GROMACS's XMGrace program.

A critical review on the biotechnological potential of Brewers' waste: Challenges and future alternatives.

In order to comply with the stringent discharge guidelines issued by governmental organizations to protect the ecosystem, the substantial amounts of effluent and sturdy wastes produced by the beer brewing process need to be discarded or handled in the most affordable and secure manner. Huge quantities of waste material released with each brew bestow a significant opportunity for the brewing sector to move towards sustainability. The concept of circular economy and the development of technological advancements in brewery waste processing have spurred interest to valorize brewery waste for implementation in various sectors of medical and food science, industrial science, and many more intriguing fields. Biotechnological methods for valorizing brewery wastes are showing a path towards green chemistry and are feasible and advantageous to environment. The study unfolds most recent prospectus for brewery waste usage and discusses major challenges with brewery waste treatment and valorization and offers suggestions for further work.

Advances in microbial based bio-inoculum for amelioration of soil health and sustainable crop production.

The adoption of sustainable agricultural practices is increasingly imperative in addressing global food security and environmental concerns, with microbial based bio-inoculums emerging as a promising approach for nurturing soil health and fostering sustainable crop production.This review article explores the potential of microbial based bio-inoculumsor biofertilizers as a transformative approach toenhance plant disease resistance and growth. It explores the commercial prospects of biofertilizers, highlighting their role in addressing environmental concerns associated with conventional fertilizers while meeting the growing demand for eco-friendly agricultural practices. Additionally, this review discusses the future prospects of biofertilizers, emphasizing the ongoing advancements in biotechnology and formulation techniques that are expected to enhance their efficacy and applicability. Furthermore, this article provides insights into strategies for the successful acceptance of biofertilizers among farmers, including the importance of quality control, assurance, and education initiatives to raise awareness about their benefits and overcome barriers to adoption. By synthesizing the current research findings and industrial developments, this review offers valuable guidance for stakeholders seeking to exploit the potential of biofertilizers or beneficial microbes to promote soil health, ensure sustainable crop production, and addressing the challenges of modern agriculture.

In silico homology modeling, docking and sequence analysis of some bacterial laccases to unravel enzymatic specificity towards lignin biodegradation.

Laccase is a delignifying enzyme that belongs to the oxidoreductase family, and it has long been investigated as a pretreatment agent in biofuel production. In this study, amino acid sequences of five bacterial laccases from Bifidobacterium breve, Klebsiella pneumonia, Pseudodesulfovibrio hydrargyri, Pseudomonas aeruginosa and Veillonella rodentium have been retrieved from UniProtKB for sequence alignment, phylogenetic analysis using MEGA 7.0 and 3 D structure prediction by homology modeling in SWISS-MODEL. Multiple sequence alignment between all the bacterial laccase sequences revealed a similar structural fold, although the overall protein sequence varied greatly with the substrate binding sites. Further molecular docking in AutoDock Vina and MD stimulation (MDS) in GROMACS for those modelled enzymes were performed considering both apo and ligand bound structures considering both apo and its ligand bound form. Investigation of molecular interaction utilizing docking of five bacterial laccases with three substrates (ABTS, DMP and Guaiacol) revealed that ABTS with K. pneumoniae laccase had the highest binding energy of -7.00 kcal/mol. In the current MDS investigation, bacterial laccases demonstrated greater binding and substrate energy in the ligand bound complex than in the apo form for ABTS, DMP and Guaiacol. In most cases of bacterial laccase, MDS revealed that DMP bound complex was more stable within an average RMSD value lower than 0.5 nm throughout 100 ns time scale. Thus, in silico studies undertaken in this work will be useful in determining the stable enzyme-substrate complex which further might improve the enzymatic catalysis of bacterial laccases for lignin breakdown and biofuel generation.

Relation of ACE2 with co-morbidity factors in SARS-CoV-2 pathogenicity.

In the last 3 years of the pandemic situation, SARS-CoV-2 caused a significant number of deaths. Infection rates for symptomatic and asymptomatic patients are higher than that for death. Eventually, researchers explored that the major deaths are attributed to several comorbidity factors. The confounding factors and gender-associated infection/death rate are observed globally. This suggests that SARS-CoV-2 selects the human system recognizing the internal comorbid environment. This article explored the influences of hypertension, diabetes, cardiovascular, and renovascular disorders in COVID-19 severity and mortality. Brief mechanistic layouts have been presented here, indicating some of the comorbidity as the critical determinant in the COVID-19 pathogenesis and related mortality.

Evaluation of substrate specificity and catalytic promiscuity of Bacillus albus cellulase: an insight into in silico proteomic study aiming at enhanced production of renewable energy.

Cellulases are enzymes that aid in the hydrolysis of cellulosic fibers and have a wide range of industrial uses. In the present in silico study, sequence alignment between cellulases from different Bacillus species revealed that most of the residues are conserved in those aligned enzymes. Three dimensional structures of cellulase enzymes from 23 different Bacillus species have been predicted and based on the alignment between the modeled structures, those enzymes have been categorized into 7 different groups according to the homology in their conformational folds. There are two structural contents in Gr-I cellulase namely ß1-α2 and ß3-α5 loops which varies greatly according to their static position. Molecular docking study between the B. albus cellulase and its various cellulosic substrates including xylanoglucan oligosaccharides revealed that residues viz. Phe154, Tyr258, Tyr282, Tyr285, and Tyr376 of B. albus cellulase are significantly involved in formation stacking interaction during enzyme-substrate binding. Residue interaction network and binding energy analysis for the B. albus cellulase with different cellulosic substrates depicted the strong affinity of XylGlc3 substrate with the receptor enzyme. Molecular interaction and molecular dynamics simulation studies exhibited structural stability of enzyme-substrate complexes which are greatly influenced by the presence of catalytic promiscuity in their substrate binding sites. Screening of B. albus in carboxymethylcellulose (CMC) and xylan supplemented agar media revealed the capability of the bacterium in degrading both cellulose and xylan. Overall, the study demonstrated B. albus cellulase as an effective biocatalyst candidate with the potential role of catalytic promiscuity for possible applications in biofuel industries.Communicated by Ramaswamy H. Sarma.

An insight into omics analysis and metabolic pathway engineering of lignin-degrading enzymes for enhanced lignin valorization.

Lignin, a highly heterogeneous polymer of lignocellulosic biomass, is intricately associated with cellulose and hemicellulose, responsible for its strength and rigidity. Lignin decomposition is carried out through certain enzymes derived from microorganisms to promote the hydrolysis of lignin. Analyzing multi-omics data helps to emphasize the probable value of fungal-produced enzymes to degrade the lignocellulosic material, which provides them an advantage in their ecological niches. This review focuses on lignin biodegrading microorganisms and associated ligninolytic enzymes, including lignin peroxidase, manganese peroxidase, versatile peroxidase, laccase, and dye-decolorizing peroxidase. Further, enzymatic catalysis, lignin biodegradation mechanisms, vital factors responsible for lignin modification and degradation, and the design and selection of practical metabolic pathways are also discussed. Highlights were made on metabolic pathway engineering, different aspects of omics analyses, and its scope and applications to ligninase enzymes. Finally, the advantages and essential steps of successfully applying metabolic engineering and its path forward have been addressed.

Diversity and seasonal fluctuation of predominant microbial communities in Bhitarkanika, a tropical mangrove ecosystem in India.

Different groups of microorganisms are present in mangrove areas, and they perform complex interactions for nutrient and ecological balances. Since little is known about microbial populations in mangroves, this study analyzed the microbial community structure and function in relation to soil physico-chemical properties in Bhitarkanika, a tropical mangrove ecosystem in India. Spatial and seasonal fluctuations of thirteen important groups of microorganisms were evaluated from the mangrove forest sediments during different seasons, along with soil physico-chemical parameters. The overall microbial load (x10(5)cfu/g soil) in soil declined in the order of heterotrophic, free living N2 fixing, Gram-negative nitrifying, sulphur oxidizing, Gram-positive, spore forming, denitrifying, anaerobic, phosphate solubilizing, cellulose degrading bacteria, fungi and actinomycetes. Populations of the heterotrophic, phosphate solubilizing, sulphur oxidizing bacteria and fungi were more represented in the rainy season, while, Gram-negative, Gram-positive, nitrifying, denitrifying, cellulose decomposing bacteria and actinomycetes in the winter season. The pool size of most of other microbes either declined or maintained throughout the season. Soil nutrients such as N, P, K (Kg/ha) and total C (%) contents were higher in the rainy season and they did not follow any common trend of changes throughout the study period. Soil pH and salinity (mS/cm) varied from 6-8 and 6.4-19.5, respectively, and they normally affected the microbial population dynamics. Determination of bacterial diversity in Bhitarkanika mangrove soil by culture method showed the predominance of bacterial genera such as Bacillus, Pseudomonas, Desulfotomaculum, Desulfovibrio, Desulfomonas, Methylococcus, Vibrio, Micrococcus, Klebsiella and Azotobacter. Principal component analysis (PCA) revealed a correlation among local environmental variables with the sampling locations on the microbial community in the mangrove soil.

Response surface methodology mediated optimization of Lignin peroxidase from Bacillus mycoides isolated from Simlipal Biosphere Reserve, Odisha, India.

BACKGROUND: Lignin is a complex polymer of phenyl propanoid units found in the vascular tissues of the plants as one of lignocellulose materials. Many bacteria secrete enzymes to lyse lignin, which can be essential to ease the production of bioethanol. Current research focused on the study of ligninolytic bacteria capable of producing lignin peroxidase (LiP) which can help in lignin biodegradation and bioethanol production. Ligninolytic bacterial strains were isolated and screened from the soil samples of Simlipal Biosphere Reserve (SBR), Odisha (India), for the determination of their LiP activity. Enzymatic assay and optimization for the LiP activity were performed with the most potent bacterial strain. The strain was identified by morphological, biochemical, and molecular methods. RESULTS: In this study, a total of 16 bacteria (Simlipal ligninolytic bacteria [SLB] 1-16) were isolated from forest soils of SBR using minimal salt medium containing lignin. Out of the 16 isolates, 9 isolates showed decolourization of methylene blue dye on LB agar plates. The bacterial isolates such as SLB8, SLB9, and SLB10 were able to decolourize lignin with 15.51%, 16.80%, and 33.02%, respectively. Further enzyme assay was performed using H2O2 as substrate and methylene blue as an indicator for these three bacterial strains in lignin containing minimal salt medium where the isolate SLB10 showed the highest LiP activity (31.711 U/mg). The most potent strain, SLB10, was optimized for enhanced LiP enzyme activity using response surface methodology. In the optimized condition of pH 10.5, temperature 30 °C, H2O2 concentration 0.115 mM, and time 42 h, SLB10 showed a maximum LiP activity of 55.947 U/mg with an increase of 1.76 times from un-optimized condition. Further chemical optimization was performed, and maximum LiP activity as well as significant dye-decolourization efficiency of SLB10 has been found in bacterial growth medium supplemented individually with cellulose, yeast extract, and MnSO4. Most notably, yeast extract and MnSO4-supplemented bacterial culture medium were shown to have even higher percentage of dye decolourization compared to normal basal medium. The bacterial strain SLB10 was identified as Bacillus mycoides according to morphological, biochemical, and molecular (16S rRNA sequencing) characterization and phylogenetic tree analysis. CONCLUSION: Result from the present study revealed the potential of Bacillus mycoides bacterium isolated from the forest soil of SBR in producing LiP enzyme that can be evaluated further for application in lignin biodegradation and bioethanol production. Scaling up of LiP production from this potent bacterial strain could be useful in different industrial applications.