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Pseudomonas putida,a robust candidate for lignocellulosicbiomass-based biorefineries, encounters challenges in metabolizing xylose. In this study, Weimberg pathway was introduced intoP. putidaEM42 under a xylose-inducible promoter, resulting in slow cell growth (0.05 h-1) on xylose.Through adaptive laboratory evolution, an evolved strain exhibited highly enhanced growth on xylose (0.36 h-1), comparable to that on glucose (0.39 h-1). Whole genome sequencing identified four mutations, with two key mutations located inPP3380andPP2219. Reverse-engineered strain 8EM42_Xyl, harboring these two mutations, showed enhanced growth on xylose but co-utilizing glucose and xylose at a rate of 0.3 g/L/h. Furthermore, 8EM42_Xyl was employed for 3-hydroxypropionic acid (3HP) production from glucose and xylose by expressing malonyl-CoA reductase and acetyl-CoA carboxylase, yielding 29 g/L in fed-batch fermentation. Moreover, the engineered strain exhibited promising performance in 3HP production from empty palm fruit bunch hydrolysate, demonstrating its potential as a promising cell factory forbiorefineries.
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Ácido Láctico/análogos & derivados , Pseudomonas putida , Xilose , Xilose/metabolismo , Pseudomonas putida/genética , Pseudomonas putida/metabolismo , Glucose/metabolismo , Fermentação , Engenharia Metabólica/métodosRESUMO
In this study, we developed a levulinic acid (LA)-inducible and antibiotic-free plasmid system mediated by HpdR/P hpdH and infA-complementation to produce 4-hydroxyvaleric acid (4-HV) from LA in an engineered Escherichia coli strain. The system was efficiently induced by the addition of the LA substrate and resulted in tight dose-dependent control and fine-tuning of gene expression. By engineering the 5' untranslated region (UTR) of hpdR mRNA, the gene expression of green fluorescent protein (GFP) increased by at least two-fold under the hpdH promoter. Furthermore, by evaluating the robustness and plasmid stability of the proposed system, the engineered strain, IRV750f, expressing the engineered 3-hydroxybutyrate dehydrogenase (3HBDH∗) and formate dehydrogenase (CbFDH), produced 82 g/L of 4-HV from LA, with a productivity of 3.4 g/L/h and molar conversion of 92% in the fed-batch cultivation (5 L fermenter) without the addition of antibiotics or external inducers. Overall, the reported system was highly beneficial for the large-scale and cost-effective microbial production of value-added products and bulk chemicals from the renewable substrate, LA.
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The present study elaborates on the propionic acid (PA) production by the well-known microbial cell factory Pseudomonas putida EM42 and its capacity to utilize biomass-derived levulinic acid (LA). Primarily, the P. putida EM42 strain was engineered to produce PA by deleting the methylcitrate synthase (PrpC) and propionyl-CoA synthase (PrpE) genes. Subsequently, a LA-inducible expression system was employed to express yciA (encoding thioesterase) from Haemophilus influenzae and ygfH (encoding propionyl-CoA: succinate CoA transferase) from Escherichia coli to improve the PA production by up to 10-fold under flask scale cultivation. The engineered P. putida EM42:ΔCE:yciA:ygfH was used to optimize the bioprocess to further improve the PA production titer. Moreover, the fed-batch fermentation performed under optimized conditions in a 5 L bioreactor resulted in the titer, productivity, and molar yield for PA production of 26.8 g/L, 0.3 g/L/h, and 83%, respectively. This study, thus, successfully explored the LA catabolic pathway of P. putida as an alternative route for the sustainable and industrial production of PA from LA.
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Inducible and tunable expression systems are essential for the microbial production of biochemicals. Five different carbon source- and substrate-inducible promoter systems were developed and further evaluated in Pseudomonas putida KT2440 by analyzing the expression of green fluorescent protein (GFP) as a reporter protein. These systems can be induced by low-cost compounds such as glucose, 3-hydroxypropionic acid (3HP), levulinic acid (LA), and xylose. 3HP-inducible HpdR/PhpdH was also efficiently induced by LA. LvaR/PlvaA and XutR/PxutA systems were induced even at low concentrations of LA (0.1 mM) and xylose (0.5 mM), respectively. Glucose-inducible HexR/Pzwf1 showed weak GFP expression. These inducer agents can be used as potent starting materials for both cell growth and the production of a wide range of biochemicals. The efficiency of the reported systems was comparable to that of conventional chemical-inducible systems. Hence, the newly investigated promoter systems are highly useful for the expression of target genes in the widely used synthetic biology chassis P. putida KT2440 for industrial and medical applications.
Assuntos
Regulação Bacteriana da Expressão Gênica , Engenharia Genética , Vetores Genéticos/genética , Pseudomonas putida/genética , Citometria de Fluxo , Expressão Gênica , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Genes Reporter , Glucose/metabolismo , Glucose/farmacologia , Ácido Láctico/análogos & derivados , Ácido Láctico/metabolismo , Ácido Láctico/farmacologia , Regiões Promotoras Genéticas , Pseudomonas putida/metabolismo , Proteínas Recombinantes/genéticaRESUMO
This work studied the production of Transglutaminase (TGase) using wheat bran as carbon source. The medium components and culture conditions were optimized by statistical Box-Behnken response surface methodology. The release of active Transglutaminase was enhanced by adding (i) protease to remove pro-region to make inactive enzyme to active form, (ii) Cetyl trimethyl ammonium bromide (CTAB) which facilitated more secretion. Under finally optimized conditions viz. 5â¯g wheat bran, protease: 39.14 U, magnesium chloride (MgCl2): 0.10â¯M, CTAB: 0.08% and inoculation size: 2% led to 4-fold (12.949⯱â¯0.061â¯IU/g) increased TGase production over that of un-optimized conditions. The application of TGase was shown to be useful in effective casein cross-linking.
Assuntos
Streptomyces , Endopeptidases , Fermentação , Resíduos Industriais , Cloreto de Magnésio , TransglutaminasesRESUMO
In the wake of the uprising global energy crisis, microalgae have emerged as an alternate feedstock for biofuel production. In addition, microalgae bear immense potential as bio-cell factories in terms of producing key chemicals, recombinant proteins, enzymes, lipid, hydrogen and alcohol. Abstraction of such high-value products (algal biorefinery approach) facilitates to make microalgae-based renewable energy an economically viable option. Synthetic biology is an emerging field that harmoniously blends science and engineering to help design and construct novel biological systems, with an aim to achieve rationally formulated objectives. However, resources and tools used for such nuclear manipulation, construction of synthetic gene network and genome-scale reconstruction of microalgae are limited. Herein, we present recent developments in the upcoming field of microalgae employed as a model system for synthetic biology applications and highlight the importance of genome-scale reconstruction models and kinetic models, to maximize the metabolic output by understanding the intricacies of algal growth. This review also examines the role played by microalgae as biorefineries, microalgal culture conditions and various operating parameters that need to be optimized to yield biofuel that can be economically competitive with fossil fuels.
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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.
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Biocombustíveis , Bioprospecção/métodos , Celulases/genética , Celulases/metabolismo , Celulose/metabolismo , Metagenoma , Metagenômica/métodos , Bioprospecção/tendências , Microbiologia Ambiental , Metagenômica/tendênciasRESUMO
BACKGROUND: Saccharification is the most crucial and cost-intensive process in second generation biofuel production. The deficiency of ß-glucosidase in commercial enzyme leads to incomplete biomass hydrolysis. The decomposition of biomass at high temperature environments leads us to isolate thermotolerant microbes with ß-glucosidase production potential. RESULTS: A total of 11 isolates were obtained from compost and cow dung samples that were able to grow at 50 °C. On the basis of qualitative and quantitative estimation of ß-glucosidase enzyme production, Bacillus subtilis RA10 was selected for further studies. The medium components and growth conditions were optimized and ß-glucosidase enzyme production was enhanced up to 19.8-fold. The ß-glucosidase from B. subtilis RA10 retained 78% of activity at 80 °C temperature and 68.32% of enzyme activity was stable even at 50 °C after 48 h of incubation. The supplementation of ß-glucosidase from B. subtilis RA10 into commercial cellulase enzyme resulted in 1.34-fold higher glucose release. Furthermore, ß-glucosidase was also functionally elucidated by cloning and overexpression of full length GH1 family ß-glucosidase gene from B. subtilis RA10. The purified protein was characterized as thermostable ß-glucosidase enzyme. CONCLUSIONS: The thermostable ß-glucosidase enzyme from B. subtilis RA10 would facilitate efficient saccharification of cellulosic biomass into fermentable sugar. Consequently, after saccharification, thermostable ß-glucosidase enzyme would be recovered and reused to reduce the cost of overall bioethanol production process.
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There is a growing interest in the use of bioinoculants to assist mineral fertilizers in improving crop production and yield. Azotobacter and Pseudomonas are two agriculturally relevant strains of bacteria which have been established as efficient bioinoculants. An experiment involving addition of graded concentrations of zinc oxide (ZnO) nanoparticles was undertaken using log phase cultures of Azotobacter and Pseudomonas. Growth kinetics revealed a clear trend of gradual decrease with Pseudomonas; however, Azotobacter exhibited a twofold enhancement in growth with increase in the concentration of ZnO concentration. Scanning electron microscopy (SEM), supported by energy-dispersive X-ray (EDX) analyses, illustrated the significant effect of ZnO nanoparticles on Azotobacter by the enhancement in the abundance of globular biofilm-like structures and the intracellular presence of ZnO, with the increase in its concentration. It can be surmised that extracellular mucilage production in Azotobacter may be providing a barrier to the nanoparticles. Further experiments with Azotobacter by inoculation of wheat and tomato seeds with ZnO nanoparticles alone or bacteria grown on ZnO-infused growth medium revealed interesting results. Vigour index of wheat seeds reduced by 40-50% in the presence of different concentrations of ZnO nanoparticles alone, which was alleviated by 15-20%, when ZnO and Azotobacter were present together. However, a drastic 50-60% decrease in vigour indices of tomato seeds was recorded, irrespective of Azotobacter inoculation.
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Azotobacter/efeitos dos fármacos , Produtos Agrícolas/efeitos dos fármacos , Pseudomonas/efeitos dos fármacos , Solanum lycopersicum/efeitos dos fármacos , Triticum/efeitos dos fármacos , Óxido de Zinco/metabolismo , Óxido de Zinco/toxicidade , Azotobacter/crescimento & desenvolvimento , Carga Bacteriana , Biofilmes/efeitos dos fármacos , Microscopia Eletrônica de Varredura , Nanopartículas/metabolismo , Nanopartículas/toxicidade , Pseudomonas/crescimento & desenvolvimento , Espectrometria por Raios XRESUMO
The holocellulase from Aspergillus niger SH3 was characterized and found to contain 125 proteins including cellulases (26), hemicellulases (21), chitinases (10), esterases (6), amylases (4) and hypothetical protein (32). The crude enzyme was immobilized on five different nanoparticles (NPs) via physical adsorption and covalent coupling methods. The enzyme-nanoparticle complexes (ENC) were screened for protein binding, enzymatic activities and immobilization efficiency. Magnetic enzyme-nanoparticle complexes (MENC) showed higher immobilization efficiency (60-80%) for most of the enzymes. MENC also showed better catalytic efficiencies in term of higher Vmax and lower Km than free enzyme. Saccharification yields from alkali treated paddy straw were higher (375.39mg/gds) for covalently immobilized MENC than free enzyme (339.99mg/gds). The immobilized enzyme was used for two cycles of saccharification with 55% enzyme recovery. Hence, this study for the first time demonstrated the immobilization of indigenous enzyme and its utilization for saccharification of paddy straw.
Assuntos
Celulases/química , Celulases/metabolismo , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Compostos Férricos/química , Nanopartículas/química , Aspergillus niger/citologia , Aspergillus niger/enzimologia , Carboidratos/química , Produtos Agrícolas/química , Espaço Extracelular/enzimologia , Holoenzimas/química , Holoenzimas/metabolismo , Concentração de Íons de Hidrogênio , Hidrólise , Cinética , TemperaturaRESUMO
ß-glucosidase is a crucial element of the microbial cellulose multienzyme complex since it is responsible for the regulation of the entire cellulose hydrolysis process. Therefore, the aim of the present work was to explore the diversity and distribution of glycosyl hydrolase family 1 ß-glucosidase genes in three different environmental niches including, Himalayan soil, cow dung and compost by metagenomic approach. Preliminary evaluation through metabolic profiling using BIOLOG based utilization patterns of carbon, nitrogen, phosphorus and sulfur revealed the environment and substrate specific nature of the indigenous microbial population. Furthermore, clonal library selection, screening and sequence analysis revealed that most of the GH1 ß-glucosidase proteins had low identities with the available database. Analysis of the distribution of GH1 ß-glucosidase gene fragments and ß-glucosidase producing microbial community revealed the environment specific nature. The OTUs obtained from Himalayan soil and compost metagenomic libraries were grouped into 19 different genera comprising 6 groups. The cow dung sample displayed the least diversity of GH1 ß-glucosidase sequences, with only 14 genera, distributed among three groups- Bacteroidetes, Firmicutes, and Actinobacteria. The metagenomic study coupled with metabolic profiling of GH1 ß-glucosidase illustrated the existence of intricate relationship between the geochemical environmental factors and inherent microbial community.
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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-ß-glucanase, ß-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±1.50mg/gds), xylose (121.04±1.25mg/gds) and arabinose (56.13±0.56mg/gds), thereby confirming the potential of the enzyme cocktail in bringing about considerable conversion of lignocellulosic polysaccharides to sugar monomers.
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Aspergillus/metabolismo , Espaço Extracelular/metabolismo , Proteoma , Proteômica , Aspergillus/genética , Aspergillus/crescimento & desenvolvimento , Fermentação , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Regulação Enzimológica da Expressão Gênica , Regulação Fúngica da Expressão Gênica , Hidrólise , Proteômica/métodos , SolventesRESUMO
A proteolytic strain of Bacillus pumilus MP 27 was isolated from water samples of Southern ocean produced alkaline protease. Since protease production need expensive ingredients, an economically viable process was developed by using low cost carbon source, wheat straw, supplemented with peptone. This protease was active within temperature ranges 10-70°C at pH 9. This process was optimized by response surface methodology using a Box Bekhman design by Design Expert 7.0 software that increased the protease activity to 776.5 U/ml. Moreover, the enzyme was extremely stable at a broad range of temperature and pH retaining 69% of its activity at 50°C and 70% at pH 11. The enzyme exhibited excellent compatibility with surfactants and commercial detergents, showing 87% stability with triton X-100 and 100% stability with Tide commercial detergent. The results of the wash performance analysis demonstrated considerably good de-staining at 50 and 4°C with low supplementation (109 U/ml). Molecular modeling of the protease revealed the presence of serine proteases, subtilase family and serine active site and further docking supported the association of catalytic site with the various substrates. Certainly, such protease can be considered as a good detergent additive in detergent industry with a possibility to remove the stains effectively even in a cold wash.
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Eisenia foetida and Perionyx excavatus are potent vermicomposting earthworms having immense importance in organic matter recycling under tropical conditions, particularly in India. Comparative assessment of the cultivable gut microbiome of these two epigeic earthworms after growth on lignocellulosic biomass, revealed populations of 3.2-8.3 × 10(9) CFU. Diversity analyses using 16S rDNA sequences revealed that the major dominating classes were Firmicutes (50-60%), followed by Actinobacteria (26.7-33%), and Alphaproteobacteria (5.6-6.7%). Despite exhibiting similar diversity indices and species richness, Betaproteobacteria (6.7%) and Gammaproteobacteria (11.1%) were solely present in E. foetida and P. excavatus, respectively. A set of 33 distinct morphotypes, including 18 from E. foetida and 15 from P. excavatus were selected. Carbohydrate utilization profiles generated using Hi-Carbo™ kits revealed that the isolates from the gut of P. excavatus - Arthrobacter pascens IARI-L13 and Bacillus subtilis IARIC were able to utilize 54 and 51.4% of the carbohydrates tested. Sorbose was not utilized, while unusual carbohydrates - adonitol and methyl-d-mannoside were utilized only by members from the gut of P. excavatus, while melizitose was utilized by those uniquely by E. foetida microbiome. Functional characterization revealed that ß-glucosidase activity was most prevalent in the culturable microbial community. Alkaline and acid phosphatase activity was more widespread in the E. foetida gut microbiome. All the culturable gut bacterial isolates produced ammonia, but IAA was detected only in five cultures. The unique functional attributes of the two culturable microbiomes, grown on a similar diet, reveals the significance of proper selection of earthworm substrate combinations for effective vermicomposting.
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Actinobacteria/metabolismo , Amônia/metabolismo , Firmicutes/metabolismo , Microbioma Gastrointestinal , Oligoquetos/microbiologia , Proteobactérias/metabolismo , Fosfatase Ácida/metabolismo , Agricultura , Fosfatase Alcalina/metabolismo , Animais , Metabolismo dos Carboidratos , Ácidos Indolacéticos/metabolismo , Lignina/metabolismo , Microbiologia do Solo , beta-Glucosidase/metabolismoRESUMO
A successful lignocellulosic ethanol production process needs to address the technological impediments such as cost-competitiveness and sustainability of the process. Effective biomass utilization requires a repertoire of enzymes including various accessory enzymes. Developing an enzyme preparation with defined hydrolytic activities can circumvent the need for supplementing cellulases with accessory enzymes for enhanced hydrolysis. With this objective, mixture design approach was used in the present study to enhance glycoside hydrolase production of a fungal isolate, Aspergillus terreus CM20, by determining the proportion of different lignocellulosic components as enzyme inducers in the culture medium. A mixture of paddy straw and wheat straw (1.42:1.58) resulted in improved cellulolytic activities. The precipitated crude enzyme showed higher CMCase (365.03 18 IU g-1), FPase (161.48 IU g-1), avicelase (15.46 IU g-1), ß-glucosidase (920.92 IU g-1) and xylanase (9627.79 IU g-1) activities. The potential of the crude enzyme for saccharification of alkali pretreated paddy straw was also tested. Under optimum conditions, saccharification released 25.0 g L-1 of fermentable sugars. This indicates the superiority of the crude enzyme produced with respect to its hydrolytic enzyme components.
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Aspergillus/enzimologia , Glicosídeo Hidrolases/biossíntese , Lignina/metabolismo , Oryza/microbiologia , Caules de Planta/microbiologia , Biocatálise , Biocombustíveis , Hidrólise , Microbiologia Industrial/métodos , Oryza/metabolismo , Caules de Planta/metabolismo , Especificidade por SubstratoRESUMO
ß-Glucosidase is an essential part of cellulase enzyme system for efficient and complete hydrolysis of biomass. Psychrotolerant Pseudomonas lutea BG8 produced ß-glucosidase with lower temperature optima and hence can play important role in bringing down the energy requirement for bioethanol production. To enhance ß-glucosidase production, two statistical tools: Taguchi and Box-Behnken designs were applied to reveal the most influential factors and their respective concentration for maximum production of ß-glucosidase under submerged fermentation. The optimal medium composition for maximum ß-glucosidase production were 2.99% (w/v) bagasse, 0.33% (w/v) yeast extract, 0.38% (w/v) Triton X-100, 0.39% (w/v) NaNO3 , and pH 8.0 at temperature 30 °C. Under optimized conditions, ß-glucosidase production increased up to 9.12-fold (17.52 ± 0.24 IU/g) in shake flask. Large-scale production in 7-L stirred tank bioreactor resulted in higher ß-glucosidase production (23.29 ± 0.23 IU/g) within 80 H of incubation, which was 1.34-fold higher than shake flask studies. Commercial cellulase (Celluclast® 1.5L) when supplemented with this crude ß-glucosidase resulted in improved sugar release (548.4 ± 2.76 mg/gds) from paddy straw at comparatively low temperature (40 °C) of saccharification. P. lutea BG8 therefore showed great potential for cold active ß-glucosidase production and can be used as accessory enzyme along with commercial cellulase to improve saccharification efficiency.
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Biotecnologia/métodos , Carboidratos/química , Temperatura Baixa , Extratos Vegetais/química , Pseudomonas/metabolismo , beta-Glucosidase/biossíntese , beta-Glucosidase/metabolismo , Reatores Biológicos/microbiologia , Fermentação , Cinética , Estatística como AssuntoRESUMO
Epigeic earthworms can significantly hasten the decomposition of organic matter, which is known to be mediated by gut associated microflora. However, there is scanty information on the abundance and diversity of the gut bacterial flora in different earthworm genera fed with a similar diet, particularly Eisenia foetida and Perionyx excavatus. In this context, 16S rDNA based clonal survey of gut metagenomic DNA was assessed after growth of these two earthworms on lignocellulosic biomass. A set of 67 clonal sequences belonging to E. foetida and 75 to P. excavatus were taxonomically annotated using MG-RAST and RDP pipeline servers. Highest number of sequences were annotated to Proteobacteria (38-44%), followed by unclassified bacteria (14-18%) and Firmicutes (9.3-11%). Comparative analyses revealed significantly higher abundance of Actinobacteria and Firmicutes in the gut of P. excavatus. The functional annotation for the 16S rDNA clonal libraries of both the metagenomes revealed a high abundance of xylan degraders (12.1-24.1%). However, chitin degraders (16.7%), ammonia oxidizers (24.1%) and nitrogen fixers (7.4%) were relatively higher in E. foetida, while in P. excavatus; sulphate reducers and sulphate oxidizers (12.1-29.6%) were more abundant. Lignin degradation was detected in 3.7% clones of E. foetida, while cellulose degraders represented 1.7%. The gut microbiomes showed relative abundance of dehalogenators (17.2-22.2%) and aromatic hydrocarbon degraders (1.7-5.6%), illustrating their role in bioremediation. This study highlights the significance of differences in the inherent microbiome of these two earthworms in shaping the metagenome for effective degradation of different types of biomass under tropical conditions.
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Bactérias/classificação , Bactérias/genética , Biota , Microbioma Gastrointestinal , Oligoquetos/microbiologia , Animais , Bactérias/crescimento & desenvolvimento , Bactérias/isolamento & purificação , Análise por Conglomerados , Meios de Cultura/química , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Lignina/metabolismo , Metagenoma , Dados de Sequência Molecular , Filogenia , RNA Ribossômico 16S/genética , Análise de Sequência de DNARESUMO
The filamentous bacteria Streptomyces spp. produces diverse extracellular enzymes and other secondary metabolites. Proteomic analysis of the secretome of holocellulolytic Streptomyces sp. ssr-198 was done by tandem mass spectrometry using an Orbitrap Velos hybrid mass spectrometer. A wide range of hydrolytic enzymes, including glycoside hydrolases (17), proteases (17), polysaccharide lyases (3), esterases (2), and hypothetical proteins (14) were detected in the secretome analyzed. Overall, the secretome composition constituted of 12.50% cellulases, 17.50% hemicellulases, 21.25% proteases, 17.50% hypothetical proteins, and 31.25% other proteins. Comprehensive analysis of secretome will be useful in gaining better understanding of the unique role of hydrolytic enzymes in lignocellulose hydrolysis and helps in determining the industrial applications of these potent enzymes.
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Proteínas de Bactérias/análise , Hidrolases/análise , Lignina/metabolismo , Proteoma/análise , Streptomyces/química , Streptomyces/crescimento & desenvolvimento , Proteínas de Bactérias/metabolismo , Celulases/análise , Celulases/metabolismo , Hidrolases/metabolismo , Streptomyces/enzimologiaRESUMO
Parthenium sp. is a noxious weed which threatens the environment and biodiversity due to its rapid invasion. This lignocellulosic weed was investigated for its potential in biofuel production by subjecting it to mild alkali pretreatment followed by enzymatic saccharification which resulted in significant amount of fermentable sugar yield (76.6%). Optimization of enzymatic hydrolysis variables such as temperature, pH, enzyme, and substrate loading was carried out using central composite design (CCD) in response to surface methodology (RSM) to achieve the maximum saccharification yield. Data obtained from RSM was validated using ANOVA. After the optimization process, a model was proposed with predicted value of 80.08% saccharification yield under optimum conditions which was confirmed by the experimental value of 85.80%. This illustrated a good agreement between predicted and experimental response (saccharification yield). The saccharification yield was enhanced by enzyme loading and reduced by temperature and substrate loading. This study reveals that under optimized condition, sugar yield was significantly increased which was higher than earlier reports and promises the use of Parthenium sp. biomass as a feedstock for bioethanol production.
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A total of 10 cellulase-producing bacteria were isolated from soil samples irrigated with paper and pulp mill effluents. The sequencing of 16S rRNA gene revealed that all isolates belonged to different species of genus Bacillus. Among the different isolates, B. subtilis IARI-SP-1 exhibited a high degree of ß-1,4-endoglucanase (2.5 IU/ml), ß-1,4-exoglucanase (0.8 IU/ml), and ß-glucosidase (0.084 IU/ml) activity, followed by B. amyloliquefaciens IARI-SP-2. CMC was found to be the best carbon source for production of endo/exoglucanase and ß-glucosidase. The ß-1,4-endoglucanase gene was amplified from all isolates and their deduced amino acid sequences belonged to glycosyl hydrolase family 5. Among the domains of different isolates, the catalytic domains exhibited the highest homology of 93.7%, whereas the regions of signal, leader, linker, and carbohydrate-binding domain indicated low homology (73-74%). These variations in sequence homology are significant and could contribute to the structure and function of the enzyme.