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1.
Artigo em Inglês | MEDLINE | ID: mdl-34748150

RESUMO

Distilled grain waste (DGW) can be converted to organic fertilizer via aerobic composting process without inoculating exogenous microorganisms. To illustrate the material conversion mechanism, this study investigated the dynamic changes of bacterial community structure and metabolic function involved in DGW composting. Results showed that a significant increase in microbial community alpha diversity was observed during DGW composting. Moreover, unique community structures occurred at each composting stage. The dominant phyla were Firmicutes, Proteobacteria, Actinobacteriota, Bacteroidota, Myxococcota, and Chloroflexi, whose abundance varied according to different composting stages. Keystone microbes can be selected as biomarkers for each stage, and Microbispora, Chryseolinea, Steroidobacter, Truepera, and Luteimonas indicating compost maturity. Co-occurrence network analysis revealed a significant relationship between keystone microbes and environmental factors. The carbohydrate and amino acid metabolism were confirmed as the primary metabolic pathways by metabolic function profiles. Furthermore, nitrogen metabolism pathway analysis indicated that denitrification and NH3 volatilization induced higher nitrogen loss during DGW composting. This study can provide new understanding of the microbiota for organic matter and nitrogen conversion in the composting process of DGW.

2.
Front Microbiol ; 12: 744834, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34671332

RESUMO

In natural communities, microbes exchange a variety of metabolites (public goods) with each other, which drives the evolution of auxotroph and shapes interdependent patterns at community-level. However, factors that determine the strategy of public goods synthesis for a given community member still remains to be elucidated. In anaerobic methanogenic communities, energy availability of different community members is largely varied. We hypothesized that this uneven energy availability contributed to the heterogeneity of public goods synthesis ability among the members in these communities. We tested this hypothesis by analyzing the synthetic strategy of amino acids of the bacterial and archaeal members involved in four previously enriched anaerobic methanogenic communities residing in thermophilic chemostats. Our analyses indicate that most of the members in the communities did not possess ability to synthesize all the essential amino acids, suggesting they exchanged these essential public goods to establish interdependent patterns for survival. Importantly, we found that the amino acid synthesis ability of a functional group was largely determined by how much energy it could obtain from its metabolism in the given environmental condition. Moreover, members within a functional group also possessed different amino acid synthesis abilities, which are related to their features of energy metabolism. Our study reveals that energy availability is a key driver of microbial evolution in presence of metabolic specialization at community level and suggests the feasibility of managing anaerobic methanogenic communities for better performance through controlling the metabolic interactions involved.

3.
Chemosphere ; 288(Pt 2): 132389, 2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-34606893

RESUMO

Ammonia inhibition easily affects the performance of anaerobic digestion (AD) for municipal sludge and the oxidization of volatile fatty acids (VFAs) is the rate-limiting step of this process. Bioaugmentation is considered to be an effective method to alleviate ammonia inhibition of AD, but most study used the hydrogenotrophic methanogens as the bioaugmentation culture. In this study, bioaugmentation of mesophilic AD (MAD) and thermophilic AD (TAD) under ammonia inhibition with syntrophic acetate and propionate oxidizing consortia was investigated. The results showed that the bioaugmented reactors recovered earlier than control reactors with 20 (MAD) and 8 (TAD) days, respectively. The high-throughput 16S rRNA gene sequencing indicated that the relative abundance of carbohydrates fermenter (Lentimicrobium), syntrophic VFAs-oxidizing bacteria (Rikenellaceae_DMER64, Smithella and Syntrophobacter) and acetoclastic and hydrogenotrophic methanogens (Methanosaeta, Methanolinea and Methanospirillum) increased in MAD after bioaugmentation. However, part of the bioaugmentation culture could not adapt to the high free ammonia (FAN) concentration in MAD and the effect was weakened. In TAD, proteolytic bacteria (Keratinibaculum and Tepidimicrobium), syntrophic VFAs-oxidizing bacteria (Syntrophomonas) and hydrogenotrophic methanogen (Methanosarcina) were strengthened. The effect of bioaugmentation in TAD was durable even at higher organic loading rate (OLR), due to its positive influence on microbial community. These results suggested that the different bioaugmentation mechanism occurred in MAD and TAD, which are derived from the synergetic effects of ammonia tolerance and microbial interactions. Our study revealed the VFAs-oxidizing consortia as bioaugmented culture could be the potential strategy to alleviate the ammonia stress of AD.

4.
Waste Manag ; 135: 130-139, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34496309

RESUMO

Aerobic composting is a promising alternative for the recycling of rice straw (RS), and an applicable nitrogen source is necessary to improve the process. The aim of this study was to compare the performance and microbial community dynamics of RS composting using urea or protein hydrolysate from leather waste (PHL) as a nitrogen source. Results showed that PHL addition achieved a faster temperature increase rate at start-up (1.85 ℃·h-1 vs 1.07 ℃·h-1), higher volatile solid degradation efficiency (48.04% vs 46.98%), and greater germination indices (111.72% vs 89.87%) in the end products, as compared to urea. The major bacterial phyla included Proteobacteria, Firmicutes, Bacteroidetes, and Actinobacteria in both composting processes. Although the bacterial communities in both processes succeeded in a similar pattern according to different composting phases, PHL addition accelerated the succession rate of the microbial community. Co-occurrence network analysis revealed that bacterial community composition was strongly correlated with physicochemical properties such as dissolved organic carbon (DOC), NH4+, pH, temperature, and total nitrogen (TN) content. These results proved the potential of using PHL as a nitrogen source to improve the RS composting process.


Assuntos
Compostagem , Microbiota , Oryza , Esterco , Nitrogênio/análise , Hidrolisados de Proteína , Solo , Ureia
5.
Artigo em Inglês | MEDLINE | ID: mdl-34582328

RESUMO

A strictly anaerobic, thermophilic, Gram-stain-negative bacterium, named as strain S15T, was isolated from oily sludge of Shengli oilfield in PR China. Cells of strain S15T were straight or slightly curved rods with 0.4-0.8 µm width × 1.4-3 µm length and occurred mostly in pairs or short chains. Endospore-formation was not observed. The strain grew optimally at 55 °C (range from 30-65 °C), pH 6.5 (pH 6.0-8.5) and 0-30 g l-1 NaCl (optimum with 10 g l-1 NaCl). Yeast extract was an essential growth factor for strain S15T. The major cellular fatty acid was iso-C15 : 0 (58.2 %), and the main polar lipids were amino phospholipid (APL), glycolipids (GLs) and phosphatidylethanolamine (PE). The G+C content of DNA of strain S15T was 52.2 mol%. Strain S15T shared 89.8 % 16S rRNA gene similarity with the most related organism Acetomicrobium hydrogeniformans DSM 22491T in the phylum Synergistetes. The paired genomic average amino acid identity (AAI) and percentage of conserved proteins (POCP) values showed relatedness of less than 58.0 and 39.7 % with type strains of the species in the phylum Synergistetes. On the basis of phenotypic, phylogenetic and phylogenomic evidences, strain S15T constitutes a novel species in a novel genus, for the name Thermosynergistes pyruvativorans gen. nov., sp. nov. is proposed. The type strain is S15T (=CCAM 583T=JCM 33159T). Thermosynergistaceae fam. nov. is also proposed.


Assuntos
Campos de Petróleo e Gás , Ácido Pirúvico , Anaerobiose , Bactérias , Técnicas de Tipagem Bacteriana , Composição de Bases , DNA Bacteriano/genética , Ácidos Graxos/química , Fosfolipídeos , Filogenia , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
6.
Bioresour Technol ; 337: 125492, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34320771

RESUMO

This study evaluated the impact of biochar addition on nitrogen (N) loss and the process period during distilled grain waste (DGW) composting. Results from the five treatments (0, 5, 10, 15, and 20% biochar addition) indicated that 10% biochar addition (DB10) was optimal, resulting in the lowest N loss, 25.69% vs. 40.01% in the control treatment. Moreover, the DGW composting period was shortened by approximately 14 days by biochar addition. The composition of the microbial community was not significantly altered with biochar addition in each phase, however, it did accelerate the microbial succession during DGW composting. N metabolism pathway prediction revealed that biochar addition enhanced nitrification and inhibited denitrification, and the latter phenomenon was the main reason for reducing N loss during DGW composting. Based on the above results, a potential mechanism model for biochar addition to reduce N loss during the DGW composting process was established.


Assuntos
Compostagem , Microbiota , Carvão Vegetal , Esterco , Nitrogênio , Solo
7.
Sci Total Environ ; 781: 146506, 2021 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-33794455

RESUMO

Microbial community assembly mechanisms are pivotal for understanding the ecological functions of microorganisms in biogeochemical cycling in Earth's ecosystems, yet rarely investigated in the context of deep terrestrial ecology. Here, the microbial communities in the production waters collected from water injection wells and oil production wells across eight oil reservoirs throughout northern China were determined and analyzed by proportional distribution analysis and null model analysis. A 'core' microbiota consisting of three bacterial genera, including Arcobacter, Pseudomonas and Acinetobacter, and eight archaeal genera, including Archaeoglobus, Methanobacterium, Methanothermobacter, unclassified Methanobacteriaceae, Methanomethylovorans, Methanoculleus, Methanosaeta and Methanolinea, was found to be present in all production water samples. Canonical correlation analysis reflected that the core archaea were significantly influenced by temperature and reservoir depth, while the core bacteria were affected by the combined impact of the core archaea and environmental factors. Thermodynamic calculations indicate that bioenergetic constraints are the driving force that governs the enrichment of two core archaeal guilds, aceticlastic methanogens versus hydrogenotrophic methanogens, in low- and high-temperature oil reservoirs, respectively. Collectively, our study indicates that microbial community structures in wells of oil reservoirs are structured by the thermodynamic window of opportunity, through which the core archaeal communities are accommodated directly followed by the deterministic recruiting of core bacterial genera, and then the stochastic selection of some other microbial members from local environments. Our study enhances the understanding of the microbial assembly mechanism in deep terrestrial habitats. Meanwhile, our findings will support the development of functional microbiota used for bioremediation and bioaugmentation in microbial enhanced oil recovery.


Assuntos
Archaea , Campos de Petróleo e Gás , Archaea/genética , Bactérias/genética , China , Filogenia , RNA Ribossômico 16S/genética
8.
Appl Environ Microbiol ; 87(10)2021 04 27.
Artigo em Inglês | MEDLINE | ID: mdl-33712428

RESUMO

Acetic acid and furfural are the two prevalent inhibitors coexisting with glucose and xylose in lignocellulosic hydrolysate. The transcriptional regulations of Saccharomyces cerevisiae in response to acetic acid (Aa), furfural (Fur), and the mixture of acetic acid and furfural (Aa_Fur) were revealed during mixed glucose and xylose fermentation. Carbohydrate metabolism pathways were significantly enriched in response to Aa, while pathways of xenobiotic biodegradation and metabolism were significantly enriched in response to Fur. In addition to these pathways, other pathways were activated in response to Aa_Fur, i.e., cofactor and vitamin metabolism and lipid metabolism. Overexpression of Haa1p or Tye7p improved xylose consumption rates by nearly 50%, while the ethanol yield was enhanced by nearly 8% under acetic acid and furfural stress conditions. Co-overexpression of Haa1p and Tye7p resulted in a 59% increase in xylose consumption rate and a 12% increase in ethanol yield, revealing the beneficial effects of Haa1p and Tye7p on improving the tolerance of yeast to mixed acetic acid and furfural.IMPORTANCE Inhibitor tolerance is essential for S. cerevisiae when fermenting lignocellulosic hydrolysate with various inhibitors, including weak acids, furans, and phenols. The details regarding how xylose-fermenting S. cerevisiae strains respond to multiple inhibitors during fermenting mixed glucose and xylose are still unknown. This study revealed the transcriptional regulation mechanism of an industrial xylose-fermenting S. cerevisiae strain in response to acetic acid and furfural. The transcription factor Haa1p was found to be involved in both acetic acid and furfural tolerance. In addition to Haa1p, four other transcription factors, Hap4p, Yox1p, Tye7p, and Mga1p, were identified as able to improve the resistance of yeast to these two inhibitors. This study underscores the feasibility of uncovering effective transcription factors for constructing robust strains for lignocellulosic bioethanol production.


Assuntos
Ácido Acético/farmacologia , Fermentação/efeitos dos fármacos , Furaldeído/farmacologia , Proteínas de Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/efeitos dos fármacos , Fatores de Transcrição/genética , Resistência a Medicamentos , Regulação Fúngica da Expressão Gênica/efeitos dos fármacos , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Transcriptoma/efeitos dos fármacos , Xilose/metabolismo
9.
J Biosci Bioeng ; 131(5): 461-468, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33526306

RESUMO

Increasing ethanol demand and public concerns about environmental protection promote the production of lignocellulosic bioethanol. Compared to that of starch- and sugar-based bioethanol production, the production of lignocellulosic bioethanol is water-intensive. A large amount of water is consumed during pretreatment, detoxification, saccharification, and fermentation. Water is a limited resource, and very high water consumption limits the industrial production of lignocellulosic bioethanol and decreases its environmental feasibility. In this review, we focused on the potential for reducing water consumption during the production of lignocellulosic bioethanol by performing pretreatment and fermentation at high solid loading, omitting water washing after pretreatment, and recycling wastewater by integrating bioethanol production and anaerobic digestion. In addition, the feasibility of these approaches and their research progress were discussed. This comprehensive review is expected to draw attention to water competition between bioethanol production and human use.


Assuntos
Biocombustíveis , Biomassa , Biotecnologia/métodos , Etanol/metabolismo , Lignina/metabolismo , Água/metabolismo
10.
Microb Cell Fact ; 19(1): 211, 2020 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-33187525

RESUMO

BACKGROUND: Xylitol accumulation is a major barrier for efficient ethanol production through heterologous xylose reductase-xylitol dehydrogenase (XR-XDH) pathway in recombinant Saccharomyces cerevisiae. Mutated NADH-preferring XR is usually employed to alleviate xylitol accumulation. However, it remains unclear how mutated XR affects the metabolic network for xylose metabolism. In this study, haploid and diploid strains were employed to investigate the transcriptional responses to changes in cofactor preference of XR through RNA-seq analysis during xylose fermentation. RESULTS: For the haploid strains, genes involved in xylose-assimilation (XYL1, XYL2, XKS1), glycolysis, and alcohol fermentation had higher transcript levels in response to mutated XR, which was consistent with the improved xylose consumption rate and ethanol yield. For the diploid strains, genes related to protein biosynthesis were upregulated while genes involved in glyoxylate shunt were downregulated in response to mutated XR, which might contribute to the improved yields of biomass and ethanol. When comparing the diploids with the haploids, genes involved in glycolysis and MAPK signaling pathway were significantly downregulated, while oxidative stress related transcription factors (TFs) were significantly upregulated, irrespective of the cofactor preference of XR. CONCLUSIONS: Our results not only revealed the differences in transcriptional responses of the diploid and haploid strains to mutated XR, but also provided underlying basis for better understanding the differences in xylose metabolism between the diploid and haploid strains.


Assuntos
Aldeído Redutase/metabolismo , D-Xilulose Redutase/metabolismo , Saccharomyces cerevisiae/genética , Fatores de Transcrição/metabolismo , Xilose/metabolismo , Aldeído Redutase/genética , Transporte Biológico , Vias Biossintéticas , D-Xilulose Redutase/genética , Diploide , Etanol/metabolismo , Fermentação , Regulação Fúngica da Expressão Gênica , Genes Fúngicos , Haploidia , Redes e Vias Metabólicas , Mutação , Saccharomyces cerevisiae/enzimologia , Análise de Sequência de RNA , Transdução de Sinais , Transcriptoma , Xilitol/metabolismo
11.
FEMS Yeast Res ; 20(8)2020 12 16.
Artigo em Inglês | MEDLINE | ID: mdl-33201998

RESUMO

Engineered Saccharomyces cerevisiae can reduce xylose to xylitol. However, in S.cerevisiae, there are several endogenous enzymes including xylitol dehydrogenase encoded by XYL2, sorbitol dehydrogenases encoded by SOR1/SOR2 and xylulokinase encoded by XKS1 may lead to the assimilation of xylitol. In this study, to increase xylitol accumulation, these genes were separately deleted through CRISPR/Cas9 system. Their effects on xylitol yield of an industrial S. cerevisiae CK17 overexpressing Candida tropicalis XYL1 (encoding xylose reductase) were investigated. Deletion of SOR1/SOR2 or XKS1 increased the xylitol yield in both batch and fed-batch fermentation with different concentrations of glucose and xylose. The analysis of the transcription level of key genes in the mutants during fed-batch fermentation suggests that SOR1/SOR2 are more crucially responsible for xylitol oxidation than XYL2 under the genetic background of S.cerevisiae CK17. The deletion of XKS1 gene could also weaken SOR1/SOR2 expression, thereby increasing the xylitol accumulation. The XKS1-deleted strain CK17ΔXKS1 produced 46.17 g/L of xylitol and reached a xylitol yield of 0.92 g/g during simultaneous saccharification and fermentation (SSF) of pretreated corn stover slurry. Therefore, the deletion of XKS1 gene provides a promising strategy to meet the industrial demands for xylitol production from lignocellulosic biomass.


Assuntos
Fermentação , Engenharia Metabólica , Saccharomyces cerevisiae/enzimologia , Xilose/metabolismo , Aldeído Redutase/genética , Sistemas CRISPR-Cas , D-Xilulose Redutase/genética , Deleção de Genes , Glucose/metabolismo , Fosfotransferases (Aceptor do Grupo Álcool)/genética , Saccharomyces cerevisiae/genética
12.
Front Bioeng Biotechnol ; 8: 573777, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33042973

RESUMO

Surface-enhanced Raman scattering (SERS) is a useful tool for label-free analysis of bacteria at the single cell level. However, low reproducibility limits the use of SERS. In this study, for the sake of sensitive and reproducible Raman spectra, we optimized the methods for preparing silver nanoparticles (AgNPs) and depositing AgNPs onto a cell surface. We found that fast dropwise addition of AgNO3 into the reductant produced smaller and more stable AgNPs, with an average diameter of 45 ± 4 nm. Compared with that observed after simply mixing the bacterial cells with AgNPs, the SERS signal was significantly improved after centrifugation. To optimize the SERS enhancement method, the centrifugal force, method for preparing AgNPs, concentration of AgNPs, ionic strength of the solution used to suspend the cells, and density of the cells were chosen as impact factors and optimized through orthogonal experiments. Finally, the improved method could generate sensitive and reproducible SERS spectra from single Escherichia coli cells, and the SERS signals primarily arose from the cell envelope. We further verified that this optimal method was feasible for the detection of low to 25% incorporation of 13C isotopes by the cells and the discrimination of different bacterial species. Our work provides an improved method for generating sensitive and reproducible SERS spectra.

13.
Environ Sci Technol ; 54(15): 9618-9628, 2020 08 04.
Artigo em Inglês | MEDLINE | ID: mdl-32667198

RESUMO

Isovalerate is an important intermediate in anaerobic degradation of proteins/amino acids. Little is known about how this compound is degraded due to challenges in cultivation and characterization of isovalerate-degrading bacteria, which are thought to symbiotically depend on methanogenic archaea. In this study, we successfully enriched novel syntrophic isovalerate degraders (uncultivated Clostridiales and Syntrophaceae members) through operation of mesophilic and thermophilic isovalerate-fed anaerobic reactors. Metagenomics- and metatranscriptomics-based metabolic reconstruction of novel putative syntrophic isovalerate metabolizers uncovered the catabolic pathway and byproducts (i.e., acetate, H2, and formate) of isovalerate degradation, mechanisms for electron transduction from isovalerate degradation to H2 and formate generation (via electron transfer flavoprotein; ETF), and biosynthetic metabolism. The identified organisms tended to prefer formate-based interspecies electron transfer with methanogenic partners. The byproduct acetate was further converted to CH4 and CO2 by either Methanothrix (mesophilic) and Methanosarcina (thermophilic), which employed different approaches for acetate degradation. This study presents insights into novel mesophilic and thermophilic isovalerate degraders and their interactions with methanogens.


Assuntos
Bactérias , Deltaproteobacteria , Archaea , Deltaproteobacteria/genética , Metagenômica , Metano , Methanosarcina
14.
Int J Syst Evol Microbiol ; 70(5): 3361-3373, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32375973

RESUMO

A novel obligately anaerobic, thermophilic and formate-utilizing bacterium K32T was isolated from Shengli oilfield of China. Cells were straight rods (0.4-0.8 µm × 2.5-8.0 µm), Gram-stain-positive, non-spore-forming and slightly motile. Optimum growth occurred with pH of 7 and 0.5 g l-1 NaCl under temperature of 55-60 °C. Nitrate could be reduced into nitrite, syntrophic formate oxidation to methane and carbon dioxide occurred when co-culturing strain K32T and Methanothermobacter thermautotrophicus ΔH. The main cellular fatty acids were iso-C15 : 0 (24.0 %), anteiso-C15 : 0 (21.7 %), C16 : 0 (12.7 %) and C14 : 0 (10.8 %), and the main polar lipid was phosphatidylglycerol. The G+C content of the genomic DNA was 46.3 mol%. The 16S rRNA gene sequence of K32T shared ≤90.4 % of sequence similarity to closest type strains of Desulfitibacter alkalitolerans, Calderihabitans maritimus and members of the genus Moorella. Based on the phenotypic, biochemical and genotypic characterization, Zhaonella formicivorans gen. nov., sp. nov. is proposed with K32T (=CCAM 584T =DSM 107278T=CGMCC1.5297T) as the type strain, which is the first representative of Zhaonellaceae fam. nov. In addition, the order Thermoanaerobacterales and family Peptococcaceae were reclassified, and three novel families in the novel order of Moorellales ord. nov. were also proposed.


Assuntos
Firmicutes/classificação , Formiatos/metabolismo , Campos de Petróleo e Gás/microbiologia , Filogenia , Anaerobiose , Bactérias Anaeróbias/classificação , Bactérias Anaeróbias/isolamento & purificação , Técnicas de Tipagem Bacteriana , Composição de Bases , China , DNA Bacteriano/genética , Ácidos Graxos/química , Firmicutes/isolamento & purificação , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
15.
Bioresour Technol ; 306: 123091, 2020 Mar 03.
Artigo em Inglês | MEDLINE | ID: mdl-32169511

RESUMO

The aim of this work was to study the dynamic change in structure and potential function of bacterial community during dairy manure composting process using high-throughput sequencing and advanced bioinformatics tools. Alpha diversity of microbial community significantly decreased during the thermophilic phase and then recovered gradually. Beta diversity analysis showed unique community structures in different composting phases. Keystone microbes such as genus Corynebacterium, Bacillus, Luteimonas and Nonomuraea were identified for different composting phases. Six functional modules were identified for bacterial community during the composting process using co-occurrence analysis. These modules were significantly associated with temperature, pH, degradation of organic matter and maturation of compost. Predicted metagenomics analysis showed that the relative abundance of amino acid, lipid, energy and xenobiotics metabolism increased during the composting process. These results provide valuable insights into the microbiota during dairy manure composting and how the structures and metabolic functions changed in response to composting phases.

16.
Appl Biochem Biotechnol ; 191(1): 397-411, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32016903

RESUMO

This study evaluated the performance of an upflow anaerobic filter (UAF) reactor in the thermophilic methane fermentation of hypersaline molasses wastewater. The high salinity (~ 45 mS/cm) of the undiluted wastewater completely inhibited the biogas production. An acclimation strategy involving gradient dilution of the molasses wastewater was implemented to gradually increase the salt stress. Consequently, the biogas production was recovered, inhibited only slightly by the high salinity of the undiluted wastewater. The reactor steadily achieved a high total organic carbon (TOC) loading rate of 5 g/L/day, with approximately 60% TOC removal efficiency. Acclimation to the gradually increased salt stress leads to a relative abundance of some halotolerant microbes, such as bacteria from Arcobacter, Tissierella, and Ruminococcaceae, which increased as their hydrolytic and acidogenic abilities adjusted to the incremental increase in salinity. Additionally, hydrogenotrophic methanogens, especially Methanoculleus, showed greater resistance to hypersalinity than aceticlastic methanogens. These results suggest that acclimation of the fermentation microbial community to hypersalinity is an effective strategy to improve methane production from hypersaline molasses wastewater in thermophilic UAF reactors.


Assuntos
Bactérias/crescimento & desenvolvimento , Reatores Biológicos , Metano/metabolismo , Consórcios Microbianos , Melaço , Salinidade , Águas Residuárias , Anaerobiose , Bactérias/classificação , Águas Residuárias/química , Águas Residuárias/microbiologia
17.
Appl Environ Microbiol ; 86(8)2020 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-32033953

RESUMO

Biodegradation of alkanes by microbial communities is ubiquitous in nature. Interestingly, the microbial communities with high hydrocarbon-degrading performances are sometimes composed of not only hydrocarbon degraders but also nonconsumers, but the synergistic mechanisms remain unknown. Here, we found that two bacterial strains isolated from Chinese oil fields, Dietzia sp. strain DQ12-45-1b and Pseudomonas stutzeri SLG510A3-8, had a synergistic effect on hexadecane (C16 compound) biodegradation, even though P. stutzeri could not utilize C16 individually. To gain a better understanding of the roles of the alkane nonconsumer P. stutzeri in the C16-degrading consortium, we reconstructed a two-species stoichiometric metabolic model, iBH1908, and integrated in silico prediction with the following in vitro validation, a comparative proteomics analysis, and extracellular metabolomic detection. Metabolic interactions between P. stutzeri and Dietzia sp. were successfully revealed to have importance in efficient C16 degradation. In the process, P. stutzeri survived on C16 metabolic intermediates from Dietzia sp., including hexadecanoate, 3-hydroxybutanoate, and α-ketoglutarate. In return, P. stutzeri reorganized its metabolic flux distribution to fed back acetate and glutamate to Dietzia sp. to enhance its C16 degradation efficiency by improving Dietzia cell accumulation and by regulating the expression of Dietzia succinate dehydrogenase. By using the synergistic microbial consortium of Dietzia sp. and P. stutzeri with the addition of the in silico-predicted key exchanged metabolites, diesel oil was effectively disposed of in 15 days with a removal fraction of 85.54% ± 6.42%, leaving small amounts of C15 to C20 isomers. Our finding provides a novel microbial assembling mode for efficient bioremediation or chemical production in the future.IMPORTANCE Many natural and synthetic microbial communities are composed of not only species whose biological properties are consistent with their corresponding communities but also ones whose chemophysical characteristics do not directly contribute to the performance of their communities. Even though the latter species are often essential to the microbial communities, their roles are unclear. Here, by investigation of an artificial two-member microbial consortium in n-alkane biodegradation, we showed that the microbial member without the n-alkane-degrading capability had a cross-feeding interaction with and metabolic regulation to the leading member for the synergistic n-alkane biodegradation. Our study improves the current understanding of microbial interactions. Because "assistant" microbes showed importance in communities in addition to the functional microbes, our findings also suggest a useful "assistant-microbe" principle in the design of microbial communities for either bioremediation or chemical production.


Assuntos
Actinomycetales/metabolismo , Pseudomonas stutzeri/metabolismo , China , Consórcios Microbianos , Campos de Petróleo e Gás
18.
Bioresour Technol ; 302: 122851, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32007850

RESUMO

This study involved a comparison between mesophilic (MAD) and thermophilic anaerobic digestion (TAD) of municipal sludge with high (10%) solids content; the reactor performance and the response of total and active microbial communities to changes in sludge properties were monitored. Both TAD and MAD were stably maintained. TAD performed better than MAD in biogas production and volatile total solids reduction upon feeding sludge 1. TAD was slightly inhibited by ammonia, whereas the performance of MAD was improved when sludge 2 was used as the feedstock. Alpha- and beta-diversity analyses revealed significant differences in the microbial community based on DNA and RNA datasets, indicating that not all microbes function in AD. The active microbial community diversity and composition in MAD and TAD were also driven by sludge properties. Moreover, MAD showed significantly higher richness and diversity of the active microbial community compared with TAD, regardless of changes in sludge properties.


Assuntos
Microbiota , Esgotos , Amônia , Anaerobiose , Biocombustíveis , Reatores Biológicos , Metano
19.
Appl Biochem Biotechnol ; 191(3): 1010-1026, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31950447

RESUMO

Isovalerate is one of the key intermediates during anaerobic digestion treating protein-containing waste/wastewater. Investigating the effect of different kinds of inhibitors on isovalerate-degrading microbial community is necessary to develop measures for improving the effectiveness of the treatment plants. In the present study, dynamic changes in the isovalerate-degrading microbial community in presence of inhibitors (ammonium, sulfide, mixed ammonium and sulfide, and chlortetracycline (CTC)) were investigated using high-throughput sequencing of 16S rRNA gene. Our observations showed that the isovalerate-degrading microbial community responded differently to different inhibitors and that the isovalerate degradation and gas production were strongly repressed by each inhibitor. We found that sulfide inhibited both isovalerate oxidation followed by methanogenesis, while ammonium, mixed ammonium and sulfide, and CTC mainly inhibited isovalerate oxidation. Genera classified into Proteobacteria and Chloroflexi were less sensitive to inhibitors. The two dominant genera, which are potential syntrophic isovalerate oxidizers, exhibited different responses to inhibitors that the unclassified_Peptococcaceae_3 was more sensitive to inhibitors than the unclassified_Syntrophaceae. Upon comparison to acetoclastic methanogen Methanosaeta, hydrogenotrophic methanogens Methanoculleus and Methanobacterium were less sensitive to inhibitors.


Assuntos
Hemiterpenos/química , Metano/química , Microbiota , Ácidos Pentanoicos/química , Compostos de Amônio/química , Anaerobiose , Reatores Biológicos/microbiologia , Chloroflexi/efeitos dos fármacos , Clortetraciclina/química , Ácidos Graxos Voláteis/química , Microbiologia Industrial , Methanobacterium/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Nitrogênio/química , Peptococcaceae/efeitos dos fármacos , Proteobactérias/efeitos dos fármacos , RNA Ribossômico 16S/genética , Sulfetos/química , Águas Residuárias/química , Poluentes Químicos da Água , Purificação da Água/métodos
20.
Microb Ecol ; 80(1): 120-132, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31982930

RESUMO

Propionate is one of the major intermediates in anaerobic digestion of organic waste to CO2 and CH4. In methanogenic environments, propionate is degraded through a mutualistic interaction between symbiotic propionate oxidizers and methanogens. Although temperature heavily influences the microbial ecology and performance of methanogenic processes, its effect on syntrophic interaction during propionate degradation remains poorly understood. In this study, metagenomics and metatranscriptomics were employed to compare mesophilic and thermophilic propionate degradation communities. Mesophilic propionate degradation involved multiple syntrophic organisms (Syntrophobacter, Smithella, and Syntrophomonas), pathways, interactions, and preference toward formate-based electron transfer to methanogenic partners (i.e., Methanoculleus). In thermophilic propionate degradation, one syntrophic organism predominated (Pelotomaculum), interspecies H2 transfer played a major role, and phylogenetically and metabolically diverse H2-oxidizing methanogens were present (i.e., Methanoculleus, Methanothermobacter, and Methanomassiliicoccus). This study showed that microbial interactions, metabolic pathways, and niche diversity are distinct between mesophilic and thermophilic microbial communities responsible for syntrophic propionate degradation.


Assuntos
Archaea/metabolismo , Bactérias/metabolismo , Propionatos/metabolismo , Anaerobiose , Archaea/classificação , Archaea/genética , Bactérias/classificação , Bactérias/genética , Biodegradação Ambiental , Reatores Biológicos , Transporte de Elétrons , Genoma Arqueal , Genoma Bacteriano , Metagenômica , Temperatura
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