RESUMO
Wastewater from the textile industry dyeing process containing high loads of synthetic dyes leads to pollution of water with these toxic and genotoxic dyes. Much effort has been put towards developing biological systems to resolve this issue. Mycoremediation is a well-known approach using fungi to remove, degrade, or remediate pollutants and can be applied to decolorize textile dyes in industrial effluent. Fungal strains from four genera of Polyporales, namely Coriolopsis sp. TBRC 2756, Fomitopsis pinicola TBRC-BCC 30881, Rigidoporus vinctus TBRC 6770, and Trametes pocas TBRC-BCC 18705, were studied for decolorization efficiency, and R. vinctus was found to exhibit the greatest activity in removing all seven tested reactive dyes and one acid dye with a decolorization efficiency of 80% or more within 7 days under limited oxygen. This fungus simultaneously degraded multiple dyes in synthetic wastewater as well as industrial effluent from the dyeing process. To enhance the decolorization rate, various fungal consortia were formulated for testing. However, these consortia only trivially improved efficiency compared with using R. vinctus TBRC 6770 alone. Evaluation of R. vinctus TBRC 6770 decolorization ability was further performed in a 15-L bioreactor to test its ability to eliminate multiple dyes from industrial effluent. The fungus took 45 days to adapt to growth in the bioreactor and subsequently reduced dye concentration to less than 10% of the initial concentration. The following six cycles required only 4-7 days to reduce dye concentrations to less than 25%, demonstrating that the system can run efficiently for multiple cycles without the need for extra medium or other carbon sources.
Assuntos
Trametes , Águas Residuárias , Madeira , Corantes , TêxteisRESUMO
Lytic polysaccharide monooxygenases (LPMOs) are auxiliary enzymes catalyzing oxidative cleavages of cellulose chains in crystalline regions, resulting in their increasing accessibility to the hydrolytic enzyme counterparts and hence higher released sugars from biomass saccharification. In this study, a novel auxiliary protein family 9 LPMO (BgAA9) was identified from a metagenomic library derived from a thermophilic microbial community in bagasse collection site where diverse AA9 and AA10 putative sequences were annotated. The enzyme showed highest similarity to a glycoside hydrolase family 61 from Chaetomium thermophilum. Recombinant BgAA9 expressed in Pichia pastoris cleaved cellohexaose (DP6) into shorter cellooligosaccharides (DP2, DP3, and DP4). Supplementation BgAA9 to a commercial cellulase, Accellerase® 1500 showed strong synergistic effect on saccharification of Avicel® PH101, decrystallized cellulose, filter paper, and alkaline-pretreated sugarcane bagasse, resulting in 63-93% increase in the total reducing sugar yield after incubation at 50 °C for 72 h. Strong synergism was shown between BgAA9 and the cellulase with the highest total fermentable sugar yield obtained from 75:25% of Accellerase®1500:BgAA9 which released 39 mg glucose/FPU (filter paper unit) equivalent to 38.7% higher than Accellerase®1500 alone at the same total protein dosage of 5 mg/g substrate according to the mixture design study. The enzyme represented the first characterized LPMO from environmental metagenome and a potent auxiliary component for biomass saccharification. KEY POINTS: ⢠BgAA9 represents the first characterized LPMO from metagenome. ⢠12 AA families were annotated in thermophilic bagasse fosmid library by NGS. ⢠BgAA9 showed homology to Cel61 in Chaetomium thermophilum. ⢠BgAA9 oxidized cellohexaose and PASC to DP2, DP4, and DP6. ⢠BgAA9 showed strong synergism to Accellerase on bagasse hydrolysis.
Assuntos
Metagenoma , Oxigenases de Função Mista , Celulose , Chaetomium , Oxigenases de Função Mista/genética , Polissacarídeos , SaccharomycetalesRESUMO
The diversity and assembly of activated sludge microbiomes play a key role in the performances of municipal wastewater treatment plants (WWTPs), which are the most widely applied biotechnological process systems. In this study, we investigated the microbiomes of municipal WWTPs in Bangkok, Wuhan, and Beijing that respectively represent tropical, subtropical, and temperate climate regions, and also explored how microbiomes assembled in these municipal WWTPs. Our results showed that the microbiomes from these municipal WWTPs were significantly different. The assembly of microbiomes in municipal WWTPs followed deterministic and stochastic processes governed by geographical location, temperature, and nutrients. We found that both taxonomic and phylogenetic α-diversities of tropical Bangkok municipal WWTPs were the highest and were rich in yet-to-be-identified microbial taxa. Nitrospirae and ß-Proteobacteria were more abundant in tropical municipal WWTPs, but did not result in better removal efficiencies of ammonium and total nitrogen. Overall, these results suggest that tropical and temperate municipal WWTPs harbored diverse and unique microbial resources, and the municipal WWTP microbiomes were assembled with different processes. Implications of these findings for designing and running tropical municipal WWTPs were discussed. KEY POINTS: ⢠Six WWTPs of tropical Thailand and subtropical and temperate China were investigated. ⢠Tropical Bangkok WWTPs had more diverse and yet-to-be-identified microbial taxa. ⢠Microbiome assembly processes were associated with geographical location.
Assuntos
Microbiota , Purificação da Água , Pequim , China , Filogenia , Esgotos , Tailândia , Eliminação de Resíduos Líquidos , Águas ResiduáriasRESUMO
OBJECTIVE: To develop an endo-ß-1,4-xylanase with high specificity for production of prebiotic xylooligosaccharides that optimally works at moderate temperature desirable to reduce the energy cost in the production process. RESULTS: The xylB gene, encoding for a glycosyl hydrolase family 11 xylanase from a thermoresistant fungus, Aspergillus niger BCC14405 was expressed in a methylotrophic yeast P. pastoris KM71 in a secreted form. The recombinant XylB showed a high specific activity of 3852 and 169 U mg-1 protein on beechwood xylan and arabinoxylan, respectively with no detectable side activities against different forms of cellulose (Avicel Ò PH101 microcrystalline cellulose, phosphoric acid swollen cellulose and carboxymethylcellulose). The enzyme worked optimally at 45 °C, pH 6.0. It showed a specific cleavage pattern by releasing xylobiose (X2) as the major product from xylooligosaccharides (X3 to X6) substrates. The highest XOS yield of 708 mg g-1 substrate comprising X2, X3 and X6 was obtained from beechwood xylan hydrolysis. CONCLUSION: The enzyme is potent for XOS production and for saccharification of lignocellulosic biomass.
Assuntos
Aspergillus niger/química , Endo-1,4-beta-Xilanases/genética , Glucuronatos/biossíntese , Oligossacarídeos/biossíntese , Xilanos/metabolismo , Aspergillus niger/enzimologia , Endo-1,4-beta-Xilanases/isolamento & purificação , Estabilidade Enzimática/genética , Glucuronatos/química , Concentração de Íons de Hidrogênio , Hidrólise , Oligossacarídeos/química , Especificidade por Substrato , Temperatura , Xilanos/genéticaRESUMO
Lignocellulose pretreatment produces various toxic inhibitors that affect microbial growth, metabolism, and fermentation. Zymomonas mobilis is an ethanologenic microbe that has been demonstrated to have potential to be used in lignocellulose biorefineries for bioethanol production. Z. mobilis biofilm has previously exhibited high potential to enhance ethanol production by presenting a higher viable cell number and higher metabolic activity than planktonic cells or free cells when exposed to lignocellulosic hydrolysate containing toxic inhibitors. However, there has not yet been a systematic study on the tolerance level of Z. mobilis biofilm compared to planktonic cells against model toxic inhibitors derived from lignocellulosic material. We took the first insight into the concentration of toxic compound (formic acid, acetic acid, furfural, and 5-HMF) required to reduce the metabolic activity of Z. mobilis biofilm and planktonic cells by 25% (IC25 ), 50% (IC50 ), 75% (IC75 ), and 100% (IC100 ). Z. mobilis strains ZM4 and TISTR 551 biofilm were two- to three fold more resistant to model toxic inhibitors than planktonic cells. Synergetic effects were found in the presence of formic acid, acetic acid, furfural, and 5-HMF. The IC25 of Z. mobilis ZM4 biofilm and TISTR 551 biofilm were 57 mm formic acid, 155 mm acetic acid, 37.5 mm furfural and 6.4 mm 5-HMF, and 225 mm formic acid, 291 mm acetic acid, 51 mm furfural and 41 mm 5-HMF, respectively. There was no significant difference found between proteomic analysis of the stress response to toxic inhibitors of Z. mobilis biofilm and planktonic cells on ZM4. However, TISTR 551 biofilms exhibited two proteins (molecular chaperone DnaK and 50S ribosomal protein L2) that were up-regulated in the presence of toxic inhibitors. TISTR 551 planktonic cells possessed two types of protein in the group of 30S ribosomal proteins and motility proteins that were up-regulated.
Assuntos
Antibacterianos/metabolismo , Biotransformação/efeitos dos fármacos , Etanol/metabolismo , Lignina/metabolismo , Zymomonas/efeitos dos fármacos , Zymomonas/metabolismo , Fermentação , Concentração Inibidora 50 , Proteoma/análise , Zymomonas/crescimento & desenvolvimentoRESUMO
Alcohol oxidase (AOX) functions in oxidation of primary alcohols into the corresponding aldehydes with potential on catalyzing synthesis reactions in chemical industry. In this study, AOX from a thermotolerant methylotrophic yeast, Ogataea thermomethanolica (OthAOX) was purified to high homogeneity using a single step chromatographic separation on a DEAE-Sepharose column. The purified OthAOX had a specific activity of 15.34 U/mg with 77.5% recovery yield. The enzyme worked optimally at 50⯰C in an alkaline range (pH 9.0). According to kinetic analysis, OthAOX showed a higher affinity toward short-chain aliphatic primary alcohol with the Vmax, Km, and kcat of 0.24â¯nmol/min, 0.27â¯mM, and 3628.8 min-1, respectively against methanol. Addition of alginic acid (0.35%) showed a protective effect on enhancing thermal stability of the enzyme, resulting in 72% increase in its half-life at 40⯰C under the operational conditions. This enzyme represents a promising candidate for conversion of bioethanol to acetaldehyde as secondary chemical in biorefinery.
Assuntos
Oxirredutases do Álcool , Proteínas Fúngicas , Saccharomycetales/enzimologia , Oxirredutases do Álcool/química , Oxirredutases do Álcool/isolamento & purificação , Estabilidade Enzimática , Proteínas Fúngicas/química , Proteínas Fúngicas/isolamento & purificaçãoRESUMO
Pitchers are specialized digestive organs of carnivorous plants which evolved for trapping prey and represent a unique environment harboring hidden diversity of unexplored microbes forming transient hydrolytic microcosms. In this study, the diversity of bacterial communities in the pitcher fluids of seven local Nepenthes found in Thailand was assessed by tagged 16S ribosomal RNA (rRNA) gene amplicon sequencing on an Ion PGM™ platform. A total of 1,101,000 filtered sequences were obtained which were taxonomically classified into 20 phyla, 48 classes, 72 orders, 153 families, and 442 genera while the remainder (1.43 %) could not be assigned to any existing taxa. Proteobacteria represented the predominant members in closed pitchers and more diversified bacterial taxa particularly Bacteriodetes and Actinobacteria, showed increasing abundance in open pitchers containing insect bodies. Principal coordinate analysis revealed that distribution of bacterial taxa was not significantly related to the Nepenthes species but strongly correlated to the pH of the pitcher fluids (pH 1.7-6.7). Acidicella was a highly dominant bacterial genus in acidic pitcher fluids while Dyella and Mycobacterium were also common genera in most pitchers. A unique microbial community structure was found in Nepenthes ampullaria which could reflect their adaptation to digest leaf litter, in addition to insect prey. The work revealed the highly unexplored nature of bacterial microcosms in Nepenthes pitcher fluids and provides insights into their community structure in this unique ecological system.
Assuntos
Bactérias/classificação , Biomassa , Traqueófitas/microbiologia , Bactérias/genética , Bactérias/isolamento & purificação , DNA Bacteriano/genética , Concentração de Íons de Hidrogênio , Metagenômica , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Especificidade da Espécie , Tailândia , Traqueófitas/químicaRESUMO
Industrial bagasse collection sites at sugar mills are an important resource for biomass-based industries and represent a unique ecological niche in lignocellulose degradation. In this study, microbial community structures at regions with varying microenvironmental conditions contained within a bagasse collection site were explored using tagged 16S rRNA gene pyrosequencing. Overall, remarkable differences in microbial community structures were found in aerobic surface and oxygen-limited interior regions of the pile. A variety of Alphaproteobacteria and Gammaproteobacteria represented the majority of bacteria in the aerobic upper-pile regions with the predominance of acetic acid bacteria towards the outer surface. Diverse Proteobacteria, Bacteroidetes, and Acidobacteria represented the predominant phyla at the exterior soil-contact pile base with an increasing abundance of anaerobic Spirochaetes with the increasing depth, where it shared similar community structures to that in the open-field soil from decomposed bagasse. Using complementary shotgun pyrosequencing, a variety of genes encoding various glycosyl hydrolases targeting cellulose and hemicellulose degradation were identified in the oxygen-limited interior pile base. Most were relevant to orders Clostridiales, Bacteroidales, Sphingobacteriales, and Cytophagales, suggesting their role in lignocellulose degradation in this region, as evidenced by the decrease in cellulose and respective increase in lignin fractions of the biomass. Partial carbon flux in the anoxic region was metabolized through mixed methanogenesis pathways as suggested by the annotated functional genes in methane synthesis. This study gives insights into native microbial community structures and functions in this unique lignocellulose degrading environment and provides the basis for controlling microbial processes important for utilization of bagasse in bio-industries.
Assuntos
Bactérias/classificação , Bactérias/isolamento & purificação , Celulose/análise , Resíduos Industriais/análise , Filogenia , Bactérias/genética , Bactérias/metabolismo , Biodiversidade , Lignina/metabolismo , Dados de Sequência MolecularRESUMO
A primary tropical peat swamp forest is a unique ecosystem characterized by long-term accumulation of plant biomass under high humidity and acidic water-logged conditions, and is regarded as an important terrestrial carbon sink in the biosphere. In this study, the microbial community in the surface peat layer in Pru Toh Daeng, a primary tropical peat swamp forest, was studied for its phylogenetic diversity and metabolic potential using direct shotgun pyrosequencing of environmental DNA, together with analysis of 16S rRNA gene library and key metabolic genes. The community was dominated by aerobic microbes together with a significant number of facultative and anaerobic microbial taxa. Acidobacteria and diverse Proteobacteria (mainly Alphaproteobacteria) constituted the major phylogenetic groups, with minor representation of archaea and eukaryotic microbes. Based on comparative pyrosequencing dataset analysis, the microbial community showed high metabolic versatility of plant polysaccharide decomposition. A variety of glycosyl hydrolases targeting lignocellulosic and starch-based polysaccharides from diverse bacterial phyla were annotated, originating mostly from Proteobacteria, and Acidobacteria together with Firmicutes, Bacteroidetes, Chlamydiae/Verrucomicrobia, and Actinobacteria, suggesting the key role of these microbes in plant biomass degradation. Pyrosequencing dataset annotation and direct mcrA gene analysis indicated the presence of methanogenic archaea clustering in the order Methanomicrobiales, suggesting the potential on partial carbon flux from biomass degradation through methanogenesis. The insights on the peat swamp microbial assemblage thus provide a valuable approach for further study on biogeochemical processes in this unique ecosystem.
Assuntos
Bactérias/classificação , Metaboloma , Metagenômica , Filogenia , Áreas Alagadas , Bactérias/genética , Bactérias/metabolismo , Biodegradação Ambiental , Biodiversidade , Biomassa , DNA Bacteriano/genética , Biblioteca Gênica , Metagenoma , Anotação de Sequência Molecular , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , TailândiaRESUMO
Sugarcane bagasse is an important lignocellulosic by-product with potential for conversion to biofuels and chemicals in biorefinery. As a step towards an understanding of microbial diversity and the processes existing in bagasse collection sites, the microbial community in industrial bagasse feedstock piles was investigated. Molecular biodiversity analysis of 16S rDNA sequences revealed the presence of a complex bacterial community. A diverse group of mainly aerobic and facultative anaerobic bacteria was identified reflecting the aerobic and high temperature microenvironmental conditions under the pile surface. The major bacterial taxa present were identified as Firmicutes, Alpha- and Gammaproteobacteria, Acidobacteria, Bacteroidetes, and Actinobacteria. Analysis of the eukaryotic microbial assemblage based on an internal transcribed spacer revealed the predominance of diverse cellulolytic and hemicellulolytic ascomycota. A microbial interaction model is proposed, focusing on lignocellulose degradation and methane metabolism. The insights into the microbial community in this study provide a basis for efficient utilization of bagasse in lignocellulosic biomass-based industries.
Assuntos
Bactérias/classificação , Celulose/metabolismo , Indústrias , Filogenia , Saccharum/microbiologia , Bactérias/metabolismo , Biodiversidade , Biomassa , Saccharum/metabolismoRESUMO
Xylo-oligosaccharide (XO) is a promising pre-biotic with applications in food, feed and healthcare products. XO can be produced by enzymatic digestion of xylan with xylanase. In this study, we aimed to improve the biochemical properties relevant to catalysis and kinetics of X11, a thermophilic glycosyl hydrolase (GH) family 11 endo-ß-1,4-xylanase derived from a metagenomic library isolated from sugarcane bagasse, under high-temperature conditions preferred for XO synthesis. Removal of a carbohydrate-binding module (X11C) resulted in 6.5 fold greater catalytic efficiency. X11C was further improved by a Pro71Thr mutation in the X11P variant obtained from a random mutagenesis library, which exhibited 15.9 fold greater catalytic efficiency compared with wild-type X11 under the enzyme's optimal conditions of 80°C and pH 6.0. Homology modeling suggested that the improved performance of X11P could be attributed to formation of an extra H-bond between Thr71 and Ser75, which stabilizes the key catalytic residue Glu180 at the active pocket and ß-sheet layers and agrees with the respective increase in melting temperature (Tm) where X11P >X11C >X11 as determined by differential scanning fluorimetry. The X11P variant was tested for hydrolysis of beechwood xylan, which showed X6 as the major product followed by X3 and X4 XOs. The highest yield of 5.5 g total XOs product/mg enzyme was observed for X11P, equivalent to 3.7 fold higher than that of wild-type with XO production of >800 mg/g xylan. The X11P enzyme could be developed as a thermophilic biocatalyst for XO synthesis in biorefineries.
Assuntos
Biocatálise , Endo-1,4-beta-Xilanases/genética , Endo-1,4-beta-Xilanases/metabolismo , Metagenoma , Mutagênese , Oligossacarídeos/metabolismo , Temperatura , Celulose/metabolismo , Biblioteca Gênica , Hidrólise , Cinética , Saccharum/metabolismo , Especificidade por Substrato , Xilanos/metabolismoRESUMO
In this work, a metagenomic library was generated from peat-swamp forest soil obtained from Narathiwat Province, Thailand. From a fosmid library of approximately 15,000 clones, six independent clones were found to possess lipolytic activity at acidic pH. Analysis of pyrosequencing data revealed six ORFs, which exhibited 34-71% protein similarity to known lipases/esterases. A fosmid clone, designated LP8, which demonstrated the highest level of lipolytic activity under acidic conditions and demonstrated extracellular activity, was subsequently subcloned and sequenced. The full-length lipase/esterase gene, estPS2, was identified. Its deduced amino acid was closely related to a lipolytic enzyme of an uncultured bacterium, and contained the highly conserved motif of a hormone-sensitive family IV lipase. The EstPS2 enzyme exhibited highest activity toward p-nitrophenyl butyrate (C4) at 37 °C at pH 5, indicating that it was an esterase with activity and secretion characteristics suitable for commercial development.
Assuntos
Esterases/metabolismo , Lipólise , Metagenoma/genética , Microbiologia do Solo , Butiratos , Clonagem Molecular , Sequência Conservada , Esterases/genética , Esterases/isolamento & purificação , Microbiologia Industrial , Lipase , Análise de Sequência de DNA , Solo , Especificidade por Substrato , Tailândia , Árvores , Áreas AlagadasRESUMO
Plastic composited corn silk was developed as a biotic/abiotic carrier for Zymomonas mobilis biofilm formation for the purpose of ethanol production. Furthermore, we explored the use of rice straw hydrolysate as substrate in both multistage continuous culture and repeated batch processes and compared the ethanol production efficiency by two strains of Z. mobilis. Biofilm formed by bacterial strains Z. mobilis ZM4 and TISTR551 were detected, and its proficiencies were compared under various conditions by scanning electron microscopy (SEM) and crystal violet assays. The greatest biofilm formed by both strains was found on day five after the inoculation. Z. mobilis strain ZM4 grown in repeated batch biofilm reactors produced higher yields of ethanol than TISTR551 grown under the same conditions, while TISTR551 produced higher yields of ethanol in the multistage continuous process. The yields were highly maintained, with no significant differences (p < 0.05) among the three consecutive repeated batches. These experiments highlight exciting uses for agricultural byproducts in the production of ethanol using Z. mobilis biofilm reactors.
RESUMO
Recombinant Zymomonas mobilis (pGEX-4T-3 BI 120-2) was constructed to encode endo-glucanase (CelA) and endo-xylanase (Xyn11) from Z. mobilis ZM4 (ATCC 31821) and an uncultured bacterium. The recombinant was genetically engineered with the N-terminus of a predicted SecB-dependent (type II) secretion signal from phoC of Z. mobilis to translocate the enzymes extracellularly. Both the enzymes were characterized regarding their functional optimum pH and temperature, with the highest multi-enzyme activities at pH 6.0 and a temperature of 30 °C, which approximates the optimum conditions for ethanol production by Z. mobilis. The crude intracellular and extracellular fractions of the recombinant were characterized in terms of substrate specificity using carboxymethyl cellulose (CMC), beechwood xylan, filter paper, Avicel, and pretreated rice straw. The crude extracellular and intracellular enzymes with cellulolytic and xylanolytic activities were more robustly produced and secreted from the recombinant strain compared to the wild-type and ampicillin-sensitive strains, using CMC and beechwood xylan as the substrates. Ethanol production by the recombinant strain was greater than the production by the wild-type strain when pretreated rice straw was used as a sole carbon source.
Assuntos
Proteínas de Bactérias , Celulase , Endo-1,4-beta-Xilanases , Zymomonas , Proteínas de Bactérias/biossíntese , Proteínas de Bactérias/genética , Celulase/biossíntese , Celulase/genética , Endo-1,4-beta-Xilanases/biossíntese , Endo-1,4-beta-Xilanases/genética , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/genética , Zymomonas/enzimologia , Zymomonas/genéticaRESUMO
Alcohol oxidase catalyzes the oxidation of primary alcohols into the corresponding aldehydes, making it a potential biocatalyst in the chemical industry. However, the high production cost and poor operational stability of this enzyme are limitations for industrial application. Immobilization of enzyme onto solid supports is a useful strategy for improving enzyme stability. In this work, alcohol oxidase from the thermotolerant methylotrophic yeast Ogataea thermomethanolica (OthAOX) was covalently immobilized onto barium ferrite (BaFe12O19) magnetic microparticles. Among different conditions tested, the highest immobilization efficiency of 71.0 % and catalytic activity of 34.6 U/g was obtained. Immobilization of OthAOX onto magnetic support was shown by Fourier-Transformed infrared microscopy, scanning electron microscopy and X-ray diffraction. The immobilized OthAOX worked optimally at 55 °C and pH 8.0. Immobilization also improved thermostability, in which >65% of the initial immobilized enzyme activity was retained after 24 h pre-incubation at 45 °C. The immobilized enzyme showed a greater catalytic efficiency for oxidation of methanol and ethanol than free enzyme. The immobilized enzyme could be recovered by magnetization and recycled for at least three consecutive batches, after which 70% activity remained. The properties of the immobilized enzyme suggest its potential industrial application for synthesis of aldehyde.
Assuntos
Oxirredutases do Álcool/química , Compostos de Bário/química , Compostos de Bário/síntese química , Enzimas Imobilizadas/química , Compostos Férricos/química , Compostos Férricos/síntese química , Imãs/química , Microesferas , Saccharomycetales/enzimologia , Oxirredutases do Álcool/metabolismo , Biocatálise , Técnicas de Química Sintética , Estabilidade Enzimática , Enzimas Imobilizadas/metabolismo , Concentração de Íons de Hidrogênio , Metanol/química , TemperaturaRESUMO
Coral reef ecosystems are impacted by climate change and human activities, such as increasing coastal development, overfishing, sewage and other pollutant discharge, and consequent eutrophication, which triggers increasing incidents of diseases and deterioration of corals worldwide. In this study, bacterial communities associated with four species of corals: Acropora aspera, Acropora formosa, Cyphastrea sp., and Isopora sp. in the healthy and disease stages with different diseases were compared using tagged 16S rRNA sequencing. In total, 59 bacterial phyla, 190 orders, and 307 genera were assigned in coral metagenomes where Proteobacteria and Firmicutes were pre-dominated followed by Bacteroidetes together with Actinobacteria, Fusobacteria, and Lentisphaerae as minor taxa. Principal Coordinates Analysis (PCoA) showed separated clustering of bacterial diversity in healthy and infected groups for individual coral species. Fusibacter was found as the major bacterial genus across all corals. The lower number of Fusibacter was found in A. aspera infected with white band disease and Isopora sp. with white plaque disease, but marked increases of Vibrio and Acrobacter, respectively, were observed. This was in contrast to A. formosa infected by a black band and Cyphastrea sp. infected by yellow blotch diseases which showed an increasing abundance of Fusibacter but a decrease in WH1-8 bacteria. Overall, infection was shown to result in disturbance in the complexity and structure of the associated bacterial microbiomes which can be relevant to the pathogenicity of the microbes associated with infected corals.
RESUMO
Cellulolytic enzymes play a key role on conversion of lignocellulosic plant biomass to biofuels and biochemicals in sugar platform biorefineries. In this review, we survey composite carbohydrate-active enzymes (CAZymes) among groups of cellulolytic fungi and bacteria that exist under aerobic and anaerobic conditions. Recent advances in designing effective cellulase mixtures are described, starting from the most complex microbial consortium-based enzyme preparations, to single-origin enzymes derived from intensively studied cellulase producers such as Trichoderma reesei, Talaromyces cellulolyticus, and Penicellium funiculosum, and the simplest minimal enzyme systems comprising selected sets of mono-component enzymes tailor-made for specific lignocellulosic substrates. We provide a comprehensive update on studies in developing high-performance cellulases for biorefineries.
Assuntos
Celulases/metabolismo , Biocombustíveis , Biomassa , Penicillium/enzimologia , Talaromyces/enzimologia , Trichoderma/enzimologiaRESUMO
Energy grass is a promising substrate for production of biogas by anaerobic digestion. However, the conversion efficiency is limited by the enzymatically recalcitrant nature of cellulosic wastes. In this study, an active, structurally stable mesophilic lignocellulolytic degrading microbial consortium (Np-LMC) was constructed from forest compost soil microbiota by successive subcultivation on Napier grass under facultative anoxic conditions. According to tagged 16S rRNA gene amplicon sequencing, increasing abundance of facultative Proteobacteria was found in the middle of batch cycle which was then subsequently replaced by the cellulose degraders Firmicutes and Bacteroidetes along with decreasing CMCase, xylanase, and ß-glucanase activity profiles in the supernatant after 5 days of incubation. Anaerobic/facultative bacteria Dysgonomonas and Sedimentibacter and aerobic bacteria Comamonas were the major genera found in Np-LMC. The consortium was active on degradation of the native and delignified grass. Direct shotgun sequencing of the consortium metagenome revealed relatively high abundance of genes encoding for various lignocellulose degrading enzymes in 23 glycosyl hydrolase (GH) families compared to previously reported cellulolytic microbial communities in mammalian digestive tracts. Enzymes attacking cellulose and hemicellulose were dominated by GH2, 3, 5, 9, 10, 26, 28 and 43 in addition to a variety of carbohydrate esterases (CE) and auxiliary activities (AA), reflecting adaptation of the enzyme systems to the native herbaceous substrate. The consortium identified here represents the microcosm specifically bred on energy grass, with potential for enhancing degradation of fibrous substrates in bioenergy industry.
Assuntos
Celulose/metabolismo , Metagenoma , Metagenômica , Consórcios Microbianos/genética , Pennisetum/metabolismo , Pennisetum/microbiologia , Anaerobiose , Bacteroidetes/genética , Bacteroidetes/isolamento & purificação , Bacteroidetes/metabolismo , Biocombustíveis/microbiologia , Firmicutes/genética , Firmicutes/isolamento & purificação , Firmicutes/metabolismo , Lignina/metabolismo , Proteobactérias/genética , Proteobactérias/isolamento & purificação , Proteobactérias/metabolismo , RNA Ribossômico 16S/genéticaRESUMO
Microbial Enhanced Oil Recovery (MEOR) is a promising strategy to improve recovery of residual oil in reservoirs, which can be performed by promoting specific indigenous microorganisms. In this study, we performed preliminary evaluation of the possibility of conducting MEOR at Mae Soon reservoir, an onshore reservoir in Northern Thailand. The reservoir's physicochemical characteristics, including the characteristics of the wells, the oil-bearing sandstone cores, and the reservoir's produced water, were determined. The microbiological characteristics of the oil wells in the reservoir were also investigated by submerging the reservoir's sandstone core samples, obtained from 6 oil wells, in the reservoir's produced water and in the produced water added with inorganic nutrients (KNO3 and NaH2PO4). The uncultured bacteria in both treatments were determined, using tagged 16S rRNA gene amplicon with Ion Torrent Sequencing Analysis. The effects of inorganic nutrients and the reservoir's parameters on the bacterial communities were analysed. A total number of 16,828 OTUs were taxonomically classified into 89 classes and 584 genera. In the controls (sandstone cores submerged in the produced water), the dominant bacterial populations were related to Deinococcus-Thermus, and Betaproteobacteria; while in the nutrient treated samples, there was a marked increase in the relative abundance of Gammaproteobacteria in three samples. Thermus, Acinetobacter, and Pseudomonas were the most abundant genera, and these are potential microorganisms for MEOR. Analysis of correlations between physiochemical properties of the reservoir and bacterial genera, using spearman's correlation analysis, suggested that some of the reservoir's properties, especially of the well and the rock, could influence some bacterial genera. To our knowledge, this is the first demonstration of the effect of inorganic nutrients on alteration of bacterial communities attached to reservoir's rock, and how the bacterial, physical, and chemical properties of a reservoir were co-analysed to serve as a basis for designing a MEOR process.
Assuntos
Betaproteobacteria/isolamento & purificação , DNA Bacteriano/isolamento & purificação , Gammaproteobacteria/isolamento & purificação , Campos de Petróleo e Gás/microbiologia , RNA Ribossômico 16S , TailândiaRESUMO
A novel gene belonging to the alpha-amylase family was isolated directly from community DNA obtained from soil sediments collected from Bor Khleung hot spring in Thailand. Partial sequences harboring four conserved regions of the alpha-amylase family were amplified by PCR using degenerate primers. Upstream and downstream sequences of these fragments were obtained by a genome walking approach to identify a full-length gene (Env cda13A) encoding 619 amino acids. Amino acid sequence alignments of Env Cda13A with other enzymes suggested that this enzyme was a cyclomaltodextrinase. The Env cda13A gene was expressed in Pichia pastoris as a secreted functional protein of 68 kDa. The partially purified enzyme was shown to be monomeric and hydrolyzed various maltodextrins from maltotriose to maltoheptaose and cyclomaltodextrins to give maltose and glucose as the main products. The enzyme also hydrolyzed pullulan and soluble starch to yield glucose, but the rate of hydrolysis was slow. This study demonstrated the possibility of isolating potentially novel enzymes directly from natural environments and opens an unexplored biodiversity resource in Thailand for future novel gene discoveries.