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1.
Ying Yong Sheng Tai Xue Bao ; 35(6): 1695-1704, 2024 Jun.
Artigo em Chinês | MEDLINE | ID: mdl-39235029

RESUMO

Ant nests can affect the process and seasonal dynamics of forest soil methane emissions through mediating methane oxidation/reduction microorganisms and physicochemical environments. To explore the process and mechanism by which ant nests affect soil methane emissions from Hevea brasiliensis plantation in Xishuangbanna, we measured the seasonal dynamics of methane emissions from ant nest and non-nest soils by using static chamber-gas chromatography method, and analyzed the effect of ant nesting on the changes in functional microbial diversity, microhabitats, and soil nutrients in the plantations. The results showed that: 1) Ant nests significantly affected the mean annual soil methane emissions in tropical plantation. Methane emissions in ant nest were decreased by 59.9% than the non-nest soil. In the dry season, ant nest soil was a methane sink (-1.770 µg·m-2·h-1), which decreased by 87.2% compared with the non-nest soil, while it was a methane source (0.703 µg·m-2·h-1) that increased by 152.7% in the wet season. 2) Ant nesting affected methane emissions via changing soil temperature, humidity, carbon and nitrogen concentrations. In contrast to the control, the mean annual temperature, humidity, and carbon and nitrogen content increased by 4.9%-138.5% in ant nest soils, which explained 90.1%, 97.3%, 27.3%-90.0% of the variation in methane emissions, respectively. 3) Ant nesting affected the emission dynamics through changing the diversity and community structure of methane functional microbe. Compared with the control, the average annual methanogen diversity (Ace, Chao1, Shannon, and Simpson indices) in the ant nest ranged from -9.9% to 61.2%, which were higher than those (-8.7%-31.2%) of the methane-oxidising bacterial communities. The relative abundance fluctuations of methanogens and methanotrophic bacteria were 46.76% and -6.33%, respectively. The explaining rate of methanogen diversity to methane emissions (78.4%) was higher than that of oxidizing bacterial diversity (54.5%), the relative abundance explained by the dominant genus of methanogens was 68.9%. 4) The structural equation model showed that methanogen diversity, methanotroph diversity, and soil moisture were the main factors controlling methane emissions, contributing 95.6%, 95.0%, and 91.2% to the variations of emissions, respectively. The contribution (73.1%-87.7%) of soil temperature and carbon and nitrogen components to the emission dynamics was ranked the second. Our results suggest that ant nesting mediates the seasonal dynamics of soil methane emissions, primarily through changing the diversity of methane-function microorganisms and soil water conditions. The research results deepen the understanding of the mechanism of biological regulation of methane emission in tropical forest soil.


Assuntos
Formigas , Florestas , Metano , Comportamento de Nidação , Estações do Ano , Solo , Clima Tropical , Metano/análise , Metano/metabolismo , Formigas/fisiologia , Solo/química , Animais , China , Microbiologia do Solo , Hevea/crescimento & desenvolvimento
2.
Microb Cell Fact ; 23(1): 239, 2024 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-39227830

RESUMO

BACKGROUND: The type II based CRISPR-Cas system remains restrictedly utilized in archaea, a featured domain of life that ranks parallelly with Bacteria and Eukaryotes. Methanococcus maripaludis, known for rapid growth and genetic tractability, serves as an exemplary model for studying archaeal biology and exploring CO2-based biotechnological applications. However, tools for controlled gene regulation remain deficient and CRISPR-Cas tools still need improved in this archaeon, limiting its application as an archaeal model cellular factory. RESULTS: This study not only improved the CRISPR-Cas9 system for optimizing multiplex genome editing and CRISPR plasmid construction efficiencies but also pioneered an effective CRISPR interference (CRISPRi) system for controlled gene regulation in M. maripaludis. We developed two novel strategies for balanced expression of multiple sgRNAs, facilitating efficient multiplex genome editing. We also engineered a strain expressing Cas9 genomically, which simplified the CRISPR plasmid construction and facilitated more efficient genome modifications, including markerless and scarless gene knock-in. Importantly, we established a CRISPRi system using catalytic inactive dCas9, achieving up to 100-fold repression on target gene. Here, sgRNAs targeting near and downstream regions of the transcription start site and the 5'end ORF achieved the highest repression efficacy. Furthermore, we developed an inducible CRISPRi-dCas9 system based on TetR/tetO platform. This facilitated the inducible gene repression, especially for essential genes. CONCLUSIONS: Therefore, these advancements not only expand the toolkit for genetic manipulation but also bridge methodological gaps for controlled gene regulation, especially for essential genes, in M. maripaludis. The robust toolkit developed here paves the way for applying M. maripaludis as a vital model archaeal cell factory, facilitating fundamental biological studies and applied biotechnology development of archaea.


Assuntos
Sistemas CRISPR-Cas , Edição de Genes , Mathanococcus , Mathanococcus/genética , Edição de Genes/métodos , Plasmídeos/genética , RNA Guia de Sistemas CRISPR-Cas/genética , Genoma Arqueal , Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas , Engenharia Genética/métodos
3.
J Anim Sci ; 1022024 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-39120483

RESUMO

The study aimed to investigate the effect of supplementing polyclonal antibodies (PAP) of avian origin against the ruminal methanogens Methanobrevibacter gottschalkii Ho (PAP-Ho) and M. ruminantium M1 (PAP-M1) on ruminal fermentation profile and methane production in Angus crossbred cattle (13 steers and 1 heifer). The experiment was conducted using a randomized block design with a 3 × 2 + 1 factorial arrangement, replicated in 3 periods. The factors included proportions of PAP against Ho and M1 in the mixture (100:0, 50:50, and 0:100 Ho:M1) and level of each mixture (3- or 6-mL per d). Cattle in control treatment did not receive PAP supplementation. Ruminal fluid was collected from the animals on days 0, 14, and 21 of treatment to determine of ruminal fermentation profile and ex vivo methane production. There was no effect of level of inclusion on ex vivo methane production. Supplementation with PAP-M1, either alone or in combination with PAP-Ho, decreased ex vivo methane output compared to the control group. Furthermore, in vivo molar proportion of propionate tended to be greater with PAP-M1, alone or combined with PAP-Ho, when compared with the control group. The study concluded that polyclonal antibodies against ruminal methanogens have the potential to decrease enteric methane emissions in cattle. The research provided important insights into the potential use of PAP as a strategy for reducing greenhouse gas emissions from cattle. Further research is needed to confirm these findings and to determine the practicality and feasibility of using PAP.


Methane is produced by methanogens, a type of microorganism that inhabits environments with low or no oxygen, for instance, the rumen of cattle. Methane is a greenhouse gas, and its emission contributes to climate change. Antibodies are proteins produced by the immune system when foreign bodies, called antigens, enter the body. Antibodies bind antigens and inhibit their negative actions. This study aimed to determine if oral supplementation of cattle with antibodies produced against 2 species of ruminal methanogens can decrease methane emissions from cattle. Different mixtures and doses of the 2 antibodies were supplemented to Angus crossbred animals for 21 d. Ruminal fluid from each animal was collected and incubated for 48 h to determine methane production and concentration of fermentation metabolites. There was no difference between supplementing low or high levels of antibodies. Supplementation with antibodies can result in up to 13% lower methane emissions and, in addition, production of fermentation metabolites was also affected. In summary, even a low dose of antibodies against methanogens could potentially decrease methane emissions from cattle and could become a technology to mitigate the negative effects of methane on climate.


Assuntos
Ração Animal , Dieta , Suplementos Nutricionais , Fermentação , Metano , Methanobrevibacter , Rúmen , Animais , Bovinos , Rúmen/microbiologia , Metano/metabolismo , Masculino , Ração Animal/análise , Suplementos Nutricionais/análise , Dieta/veterinária , Anticorpos , Feminino , Aves
4.
Environ Sci Pollut Res Int ; 31(38): 50333-50346, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-39093391

RESUMO

17ß-Estradiol (E2) is a novel micro-pollutant that is widely distributed in aquatic sediments and has a universal toxicological effect on aquatic organisms. However, its ecological impact on aquatic microorganisms is not yet clear. In this study, we designed a simulation system for oligotrophic water deposition in the laboratory, analyzed the impact of different concentrations of E2 pollution on the carbon metabolism activity (carbon gas emission rate) of water microorganisms. Based on high-throughput sequencing results, we revealed the impact of E2 pollution on the community structure succession and metabolic function of bacteria, archaea, and methanogens in the simulated system, explored the impact mechanism of E2 pollution on microbial carbon metabolism in water bodies. Our results suggested that E2 significantly impacts the bacterial and archaeal community rather than the methanogen community, thereby indirectly inhibiting methane production. The achievements will bridge the theoretical gap between estrogen metabolism and carbon metabolism in sedimentary environments and contribute to enriching the ecological toxicology theory of steroid estrogen.


Assuntos
Estradiol , Sedimentos Geológicos , Poluentes Químicos da Água , Estradiol/metabolismo , Sedimentos Geológicos/microbiologia , Sedimentos Geológicos/química , Microbiota/efeitos dos fármacos , Bactérias/metabolismo , Archaea/metabolismo
5.
Artigo em Inglês | MEDLINE | ID: mdl-39147218

RESUMO

BACKGROUND & AIMS: Archaea constitute one of the main 3 domains of the tree of life, distinct from eukaryotes and bacteria. Excessive luminal loads of methanogenic archaea (intestinal methanogen overgrowth [IMO]) have been implicated in the pathophysiology of various diseases, including constipation. To elucidate the phenotypical presentation of IMO, we performed a systematic review and meta-analysis of the prevalence and severity of gastrointestinal symptoms in subjects with IMO as compared with subjects without IMO. METHODS: Electronic databases, including OVID MEDLINE and Cochrane Database from inception until September 2023, were systematically searched. Prevalence rates, odds ratios (ORs), standardized mean difference (SMD), and 95% confidence intervals (CIs) of symptoms were calculated. RESULTS: Nineteen studies were included (1293 patients with IMO and 3208 controls). Patients with IMO exhibited various gastrointestinal symptoms, including bloating (78%), constipation (51%), diarrhea (33%), abdominal pain (65%), nausea (30%), and flatulence (56%). Patients with IMO had a significantly higher prevalence of constipation as compared with controls (47% vs 38%; OR, 2.04; 95% CI, 1.48-2.83; P < .0001) along with lower prevalence of diarrhea (37% vs 52%; OR, 0.58; 95% CI, 0.37-0.90; P = .01) and nausea (32% vs 45%; OR, 0.75; 95% CI, 0.60-0.94; P = .01). Patients with IMO had higher severity of constipation (SMD, 0.77; 95% CI, 0.11-1.43; P = .02) and lower severity of diarrhea (SMD, -0.71; 95% CI, -1.39 to -0.03; P = .04). Significant heterogeneity was detected. CONCLUSION: Patients with IMO exhibit a higher rate and severity of constipation along with lower rate and severity of diarrhea. The distinct phenotype of patients with IMO should be incorporated in patient-reported outcome measures and further correlated with mechanistic microbiome studies.

6.
Dig Dis Sci ; 69(9): 3344-3360, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-39001958

RESUMO

Elemental diets have been employed for the management of various diseases for over 50 years, with several mechanisms mediating their beneficial effects. Yet, they are underutilized due to poor palatability, access, cost, and lack of awareness regarding their clinical efficacy. Therefore, in this review, we aimed to systematically search and review the literature to summarize the formulation variability, mechanisms of action, clinical applications, and tolerability of the elemental diets in gastrointestinal diseases. While large prospective trials are lacking, elemental diets appear to exhibit objective and subjective clinical benefit in several diseases, including eosinophilic esophagitis, eosinophilic gastroenteritis, inflammatory bowel diseases, small intestinal bacterial overgrowth, intestinal methanogen overgrowth, chemoradiotherapy-associated mucositis, and celiac disease. Although some data support the long-term use of elemental diets as an add-on supplement for chronic pancreatitis and Crohn's disease, most of the literature on exclusive elemental diets focuses on inducing remission. Therefore, subsequent treatment strategies for maintaining remission need to be adopted in chronic/relapsing diseases. Several mechanistic pathways were identified to mediate the effects of elemental diets, including food additive and allergen-free content, high passive absorption rate, and anti-inflammatory properties. High rates of intolerance up to 40% are seen in the trials where exclusive elemental diets were administered orally due to poor organoleptic acceptability; however, when tolerated, adverse events were rare. Other limitations of elemental diets are cost, access, and lifestyle/social restrictions. Moreover, judicious use is advised in presence of a concomitant restrictive food intake disorders. Elemental diets offer a potentially highly efficacious dietary intervention with minor side effects. Palatability, cost, access, and social restrictions are common barriers of use. Prospective clinical trials are needed to elucidate the role of elemental formulas in the management of individual diseases.


Assuntos
Alimentos Formulados , Humanos , Gastroenteropatias/dietoterapia , Gastroenteropatias/terapia
7.
Dig Dis Sci ; 69(9): 3361-3368, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-39068378

RESUMO

BACKGROUND: Methanogens are associated with gut dysmotility in animal models but have not been robustly studied in humans. The WMC assesses regional transit time (TT) and pH in the GI tract. AIMS: To study the segmental TT and pH among patients with SIBO or IMO utilizing WMC. METHODS: We conducted a retrospective study of 207 patients who underwent a glucose or lactulose breath test (BT) and WMC from 2010 to 2022. Diagnosis of SIBO and IMO were based on the 2017 North American consensus criteria. TT and pH were extracted from WMC recordings. We tested for differences in means of continuous variables and frequencies of categorical variables using two-sample t tests, Wilcoxon Rank Sum test, Chi-square, and Fisher exact tests. We used R version 3.3.1 (2016-06-21) for all statistical analyses. RESULTS: A total of 196 patients met criteria, mean age 47.4 years and 155 (79.1%) females. Of the 86 (43.9%) patients with a positive BT, 42 (58.3%) had IMO only (meeting only CH4 criteria) and 30 (34.9%) met both H2 and CH4 criteria. Colonic TT was longer in patients with a positive BT compared to negative patients (40 h:29 min vs 28 h:51 min, p = 0.028). Small bowel TT and colonic TT were longer in patients with IMO compared to negative patients (SBTT: 5 h:15 min vs 4 h:32 min, p = 0.021; CTT: 44 h:23 min vs 28 h:51 min, p = 0.030). There were no significant differences in segmental pH compared to negative patients. CONCLUSION: To our knowledge, this is the largest study of patients who have undergone both BT and WMC. A positive BT was associated with delayed CTT, while having IMO only was associated with both delayed CTT and SBTT, but neither with pH. Future investigation is needed to elucidate whether changes in intestinal microbiota affect gut transit.


Assuntos
Trânsito Gastrointestinal , Intestino Delgado , Humanos , Feminino , Masculino , Trânsito Gastrointestinal/fisiologia , Estudos Retrospectivos , Pessoa de Meia-Idade , Adulto , Intestino Delgado/microbiologia , Intestino Delgado/metabolismo , Metano/metabolismo , Metano/análise , Testes Respiratórios/métodos , Endoscopia por Cápsula/métodos , Colo/microbiologia , Colo/metabolismo , Síndrome da Alça Cega/diagnóstico , Síndrome da Alça Cega/fisiopatologia , Concentração de Íons de Hidrogênio , Motilidade Gastrointestinal/fisiologia
8.
ISME Commun ; 4(1): ycae097, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-39081362

RESUMO

Anaerobic protists frequently harbour methanogenic archaea, which apparently contribute to the hosts' fermentative metabolism by consuming excess H2. However, the ecological properties of endosymbiotic methanogens remain elusive in many cases. Here we investigated the ecology and genome of the endosymbiotic methanogen of the Cononympha protists in the hindgut of the termite Coptotermes formosanus. Microscopic and 16S rRNA amplicon sequencing analyses revealed that a single species, designated here "Candidatus Methanobrevibacter cononymphae", is associated with both Cononympha leidyi and Cononympha koidzumii and that its infection rate in Cononympha cells varied from 0.0% to 99.8% among termite colonies. Fine-scale network analysis indicated that multiple 16S rRNA sequence variants coexisted within a single host cell and that identical variants were present in both Cononympha species and also on the gut wall. Thus, "Ca. Methanobrevibacter cononymphae" is a facultative endosymbiont, transmitted vertically with frequent exchanges with the gut environment. Indeed, transmission electron microscopy showed escape or uptake of methanogens from/by a Cononympha cell. The genome of "Ca. Methanobrevibacter cononymphae" showed features consistent with its facultative lifestyle: i.e., the genome size (2.7 Mbp) comparable to those of free-living relatives; the pseudogenization of the formate dehydrogenase gene fdhA, unnecessary within the non-formate-producing host cell; the dependence on abundant acetate in the host cell as an essential carbon source; and the presence of a catalase gene, required for colonization on the microoxic gut wall. Our study revealed a versatile endosymbiosis between the methanogen and protists, which may be a strategy responding to changing conditions in the termite gut.

9.
Trends Plant Sci ; 2024 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-39019767

RESUMO

The year 2023 was the warmest year since 1850. Greenhouse gases, including CO2 and methane, played a significant role in increasing global warming. Among these gases, methane has a 25-fold greater impact on global warming than CO2. Methane is emitted during rice cultivation by a group of rice rhizosphere microbes, termed methanogens, in low oxygen (hypoxic) conditions. To reduce methane emissions, it is crucial to decrease the methane production capacity of methanogens through water and fertilizer management, breeding of new rice cultivars, regulating root exudation, and manipulating rhizosphere microbiota. In this opinion article we review the recent developments in hypoxia ecology and methane emission mitigation and propose potential solutions based on the manipulation of microbiota and methanogens for the mitigation of methane emissions.

10.
J Hazard Mater ; 477: 135279, 2024 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-39047569

RESUMO

The weathering process can cause the volatilization of light components in crude oil, leading to the accumulation of total petroleum hydrocarbons (TPH) in weathered oil field soils. These TPH compounds are relatively resistant to biodegradation, posing a significant environmental hazard by contributing to soil degradation. TPH represents a complex mixture of petroleum-based hydrocarbons classified as persistent organic pollutants in soil and groundwater. The release of TPH pollutants into the environment poses serious threats to ecosystems and human health. Currently, various methods are available for TPH-contaminated soil remediation, with bioremediation technology recognized as an environmentally friendly and cost-effective approach. While converting TPH to CO2 is a common remediation method, the complex structures and diverse types of petroleum hydrocarbons (PHs) involved can result in excessive CO2 generation, potentially exacerbating the greenhouse effect. Alternatively, transforming TPH into energy forms like methane through bioremediation, followed by collection and reuse, can reduce greenhouse gas emissions and energy consumption. This process relies on the synergistic interaction between Methanogens archaea and syntrophic bacteria, forming a consortium known as the oil-degrading bacterial consortium. Methanogens produce methane through anaerobic digestion (AD), with hydrogenotrophic methanogens (HTMs) utilizing H2 as an electron donor, playing a crucial role in biomethane production. Candidatus Methanoliparia (Ca. Methanoliparia) was found in the petroleum archaeal community of weathered Oil field in northeast China. Ca. Methanoliparia has demonstrated its independent ability to decompose and produce new energy (biomethane) without symbiosis, contribute to transitioning weathered oil fields towards new energy. Therefore, this review focuses on the principles, mechanisms, and developmental pathways of HTMs during new energy production in the degradation of PHs. It also discusses strategies to enhance TPH degradation and recovery methods.


Assuntos
Biodegradação Ambiental , Hidrocarbonetos , Metano , Petróleo , Poluentes do Solo , Petróleo/metabolismo , Hidrocarbonetos/metabolismo , Poluentes do Solo/metabolismo , Metano/metabolismo , Campos de Petróleo e Gás/microbiologia , Poluição por Petróleo , Bactérias/metabolismo
11.
Appl Environ Microbiol ; 90(7): e0222023, 2024 07 24.
Artigo em Inglês | MEDLINE | ID: mdl-38916294

RESUMO

Methyl-coenzyme M reductase (MCR) catalyzes the final step of methanogenesis, the microbial metabolism responsible for nearly all biological methane emissions to the atmosphere. Decades of biochemical and structural research studies have generated detailed insights into MCR function in vitro, yet very little is known about the interplay between MCR and methanogen physiology. For instance, while it is routinely stated that MCR catalyzes the rate-limiting step of methanogenesis, this has not been categorically tested. In this study, to gain a more direct understanding of MCR's control on the growth of Methanosarcina acetivorans, we generate a strain with an inducible mcr operon on the chromosome, allowing for careful control of MCR expression. We show that MCR is not growth rate-limiting in substrate-replete batch cultures. However, through careful titration of MCR expression, growth-limiting state(s) can be obtained. Transcriptomic analysis of M. acetivorans experiencing MCR limitation reveals a global response with hundreds of differentially expressed genes across diverse functional categories. Notably, MCR limitation leads to strong induction of methylsulfide methyltransferases, likely due to insufficient recycling of metabolic intermediates. In addition, the mcr operon is not transcriptionally regulated, i.e., it is constitutively expressed, suggesting that the overabundance of MCR might be beneficial when cells experience nutrient limitation or stressful conditions. Altogether, we show that there is a wide range of cellular MCR concentrations that can sustain optimal growth, suggesting that other factors such as anabolic reactions might be rate-limiting for methanogenic growth. IMPORTANCE: Methane is a potent greenhouse gas that has contributed to ca. 25% of global warming in the post-industrial era. Atmospheric methane is primarily of biogenic origin, mostly produced by microorganisms called methanogens. Methyl-coenzyme M reductase (MCR) catalyzes methane formatio in methanogens. Even though MCR comprises ca. 10% of the cellular proteome, it is hypothesized to be growth-limiting during methanogenesis. In this study, we show that Methanosarcina acetivorans cells grown in substrate-replicate batch cultures produce more MCR than its cellular demand for optimal growth. The tools outlined in this study can be used to refine metabolic models of methanogenesis and assay lesions in MCR in a higher-throughput manner than isolation and biochemical characterization of pure protein.


Assuntos
Methanosarcina , Oxirredutases , Transcriptoma , Methanosarcina/genética , Methanosarcina/enzimologia , Methanosarcina/metabolismo , Oxirredutases/metabolismo , Oxirredutases/genética , Metano/metabolismo , Proteínas Arqueais/genética , Proteínas Arqueais/metabolismo , Regulação da Expressão Gênica em Archaea , Óperon
12.
Microbiol Resour Announc ; 13(7): e0032024, 2024 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-38864656

RESUMO

A mesophilic methanogen, Methanobrevibacter smithii B181 (DSM 11975) was previously isolated from a human fecal sample, grown on carbon dioxide and hydrogen, and subsequently sequenced. The reconstructed 1.9-Mb genome sequence of Methanobrevibacter smithii B181 contributes to our understanding of hydrogenotrophic, CO2-reducing methanogenesis in the human gut.

13.
Chemosphere ; 362: 142640, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38901697

RESUMO

Exogenous quorum sensing (QS) molecular can regulate the activity and granulation process of anaerobic sludge in anaerobic digestion process, but would be impractical as a standalone operation. Here we demonstrated that application of 1 mg L-1 boric acid assisted in an upflow anaerobic sludge blanket (UASB) reactor recovery from volatile fatty acids (VFAs) accumulation. After VFAs accumulation, the chemical oxygen demand (COD) removal suddenly reduced from 78.98% to 55.86%. The relative abundance of acetoclastic methanogens decreased from 55.79% to 68.28%-23.14%∼25.41%, and lead to the acetate accumulate as high as 1317.03 mg L-1. Granular sludge disintegrated and the average size of sludge decreased to 586.38 ± 42.45 µm. Application of 1 mg L-1 boric acid activated the interspecies QS signal (AI-2) and then induced the secretion of intraspecies QS signal (N-acyl-homoserine lactones, AHLs). AHLs were then stimulated the growth of syntrophic acetate oxidizing bacteria and hydrogenotrophic methanogen. Moreover, the concentration of acetate decreased to 224.50 mg‧L-1, and the COD removal increased to 75.10% after application of 1 mg L-1 boric acid. The activated AI-2 may induce multiple quorum-sensing circuits enhance the level of AI-2 and AHLs in parallel, and in turn assisted in anaerobic digestion recovery from VFAs accumulation.


Assuntos
Reatores Biológicos , Ácidos Graxos Voláteis , Percepção de Quorum , Esgotos , Ácidos Graxos Voláteis/metabolismo , Anaerobiose , Esgotos/microbiologia , Reatores Biológicos/microbiologia , Boro , Eliminação de Resíduos Líquidos/métodos , Ácidos Bóricos/metabolismo , Análise da Demanda Biológica de Oxigênio , Bactérias/metabolismo , Acil-Butirolactonas/metabolismo
14.
FEBS Open Bio ; 14(8): 1222-1229, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38877345

RESUMO

Methyl-coenzyme M reductase (MCR) is a multi-subunit (α2ß2γ2) enzyme responsible for methane formation via its unique F430 cofactor. The genes responsible for producing MCR (mcrA, mcrB and mcrG) are typically colocated with two other highly conserved genes mcrC and mcrD. We present here the high-resolution crystal structure for McrD from a human gut methanogen Methanomassiliicoccus luminyensis strain B10. The structure reveals that McrD comprises a ferredoxin-like domain assembled into an α + ß barrel-like dimer with conformational flexibility exhibited by a functional loop. The description of the M. luminyensis McrD crystal structure contributes to our understanding of this key conserved methanogen protein typically responsible for promoting MCR activity and the production of methane, a greenhouse gas.


Assuntos
Oxirredutases , Oxirredutases/metabolismo , Oxirredutases/química , Oxirredutases/genética , Cristalografia por Raios X , Modelos Moleculares , Metano/metabolismo , Metano/química , Humanos , Conformação Proteica , Proteínas Arqueais/metabolismo , Proteínas Arqueais/química , Proteínas Arqueais/genética
15.
Microbiol Resour Announc ; 13(7): e0035024, 2024 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-38832796

RESUMO

A methanogenic archaeon was isolated from bottom sediments in the vicinity of Lake Tanatar II (Altai, Russia), an alkaline soda lake. Here we present the draft genome sequence of Methanocalculus natronophilus sp. strain Z-7105T.

16.
Microbes Environ ; 39(5)2024.
Artigo em Inglês | MEDLINE | ID: mdl-38839370

RESUMO

Microbiologically influenced corrosion refers to the corrosion of metal materials caused or promoted by microorganisms. Although some novel iron-corrosive microorganisms have been discovered in various manmade and natural freshwater and seawater environments, microbiologically influenced corrosion in the deep sea has not been investigated in detail. In the present study, we collected slime-like precipitates composed of corrosion products and microbial communities from a geochemical reactor set on an artificial hydrothermal vent for 14.5 months, and conducted culture-dependent and -independent microbial community ana-lyses with corrosive activity measurements. After enrichment cultivation at 37, 50, and 70°C with zero-valent iron particles, some of the microbial consortia showed accelerated iron dissolution, which was approximately 10- to 50-fold higher than that of the abiotic control. In a comparative ana-lysis based on the corrosion acceleration ratio and amplicon sequencing of the 16S rRNA gene, three types of corrosion were estimated: the methanogen-induced type, methanogen-sulfate-reducing bacteria cooperative type, and sulfate-reducing Firmicutes-induced type. The methanogen-induced and methanogen-sulfate-reducing bacteria cooperative types were observed at 50°C, while the sulfate-reducing Firmicutes-induced type was noted at 37°C. The present results suggest the microbial components associated with microbiologically influenced corrosion in deep-sea hydrothermal systems, providing important insights for the development of future deep-sea resources with metal infrastructures.


Assuntos
Bactérias , Fontes Hidrotermais , Ferro , Consórcios Microbianos , RNA Ribossômico 16S , Água do Mar , Corrosão , Ferro/metabolismo , Ferro/química , Água do Mar/microbiologia , Água do Mar/química , RNA Ribossômico 16S/genética , Bactérias/classificação , Bactérias/genética , Bactérias/metabolismo , Bactérias/isolamento & purificação , Fontes Hidrotermais/microbiologia , Filogenia
17.
mLife ; 3(1): 110-118, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38827509

RESUMO

Anaerobic microbial corrosion of iron-containing metals causes extensive economic damage. Some microbes are capable of direct metal-to-microbe electron transfer (electrobiocorrosion), but the prevalence of electrobiocorrosion among diverse methanogens and acetogens is poorly understood because of a lack of tools for their genetic manipulation. Previous studies have suggested that respiration with 316L  stainless steel as the electron donor is indicative of electrobiocorrosion, because, unlike pure Fe0, 316L  stainless steel does not abiotically generate H2 as an intermediary electron carrier. Here, we report that all of the methanogens (Methanosarcina vacuolata, Methanothrix soehngenii, and Methanobacterium strain IM1) and acetogens (Sporomusa ovata and Clostridium ljungdahlii) evaluated respired with pure Fe0 as the electron donor, but only M. vacuolata, Mx. soehngenii, and S. ovata were capable of stainless steel electrobiocorrosion. The electrobiocorrosive methanogens required acetate as an additional energy source in order to produce methane from stainless steel. Cocultures of S. ovata and Mx. soehngenii demonstrated how acetogens can provide acetate to methanogens during corrosion. Not only was Methanobacterium strain IM1 not capable of electrobiocorrosion, but it also did not accept electrons from Geobacter metallireducens, an effective electron-donating partner for direct interspecies electron transfer to all methanogens that can directly accept electrons from Fe0. The finding that M. vacuolata, Mx. soehngenii, and S. ovata are capable of electrobiocorrosion, despite a lack of the outer-surface c-type cytochromes previously found to be important in other electrobiocorrosive microbes, demonstrates that there are multiple microbial strategies for making electrical contact with Fe0.

18.
FEMS Microbiol Lett ; 3712024 Jan 09.
Artigo em Inglês | MEDLINE | ID: mdl-38849297

RESUMO

Biogenic coalbed methane (CBM) is a developing clean energy source. However, it is unclear how the mechanisms of bio-methane production with different sizes of coal. In this work, pulverized coal (PC) and lump coal (LC) were used for methane production by mixed fungi-methanogen microflora. The lower methane production from LC was observed. The aromatic carbon of coal was degraded slightly by 2.17% in LC, while 11.28% in PC. It is attributed to the proportion of lignin-degrading fungi, especially Penicillium, which was reached 67.57% in PC on the 7th day, higher than that of 11.38% in LC. The results suggested that the limited interaction area in LC led to microorganisms hardly utilize aromatics. It also led the accumulation of aromatic organics in the fermentation broth in PC. Increasing the reaction area of coal and facilitating the conversion of aromatic carbon are suggested means to increase methane production in situ.


Assuntos
Biodegradação Ambiental , Carvão Mineral , Fungos , Lignina , Metano , Metano/metabolismo , Carvão Mineral/microbiologia , Fungos/metabolismo , Fungos/classificação , Lignina/metabolismo , Fermentação , Penicillium/metabolismo
19.
Chemosphere ; 361: 142588, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38866340

RESUMO

Lignin, a major component of plant biomass, remains underutilized for renewable biofuels due to its complex and heterogeneous structure. Although investigations into depolymerizing lignin using fungi are well-established, studies of microbial pathways that enable anaerobic lignin breakdown linked with methanogenesis are limited. Through an enrichment cultivation approach with inoculation of freshwater sediment, we enriched a microbial community capable of producing methane during anaerobic lignin degradation. We reconstructed the near-complete population genomes of key lignin degraders and methanogens using metagenome-assembled genomes finally selected in this study (MAGs; 92 bacterial and 4 archaeal MAGs affiliated into 45 and 2 taxonomic groups, respectively). This study provides genetic evidence of microbial interdependence in conversion of lignin to methane in a syntrophic community. Metagenomic analysis revealed metabolic linkages, with lignin-hydrolyzing and/or fermentative bacteria such as the genera Alkalibaculum and Propionispora transforming lignin breakdown products into compounds such as acetate to feed methanogens (two archaeal MAGs classified into the genus Methanosarcina or UBA6 of the family Methanomassiliicoccaceae). Understanding the synergistic relationships between microbes that convert lignin could inform strategies for producing renewable bioenergy and treating aromatic-contaminated environments through anaerobic biodegradation processes. Overall, this study offers fundamental insights into complex community-level anaerobic lignin metabolism, highlighting hitherto unknown players, interactions, and pathways in this biotechnologically valuable process.


Assuntos
Archaea , Bactérias , Biodegradação Ambiental , Biocombustíveis , Lignina , Lignina/metabolismo , Anaerobiose , Archaea/metabolismo , Archaea/genética , Bactérias/metabolismo , Bactérias/classificação , Bactérias/genética , Metano/metabolismo , Microbiota , Metagenoma
20.
Environ Sci Pollut Res Int ; 31(25): 36716-36727, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38753237

RESUMO

Thermophilic anaerobic digestion (TAD) represents a promising biotechnology for both methane energy production and waste stream treatment. However, numerous critical microorganisms and their metabolic characteristics involved in this process remain unidentified due to the limitations of culturable isolates. This study investigated the phylogenetic composition and potential metabolic traits of bacteria and methanogenic archaea in a TAD system using culture-independent metagenomics. Predominant microorganisms identified in the stable phase of TAD included hydrogenotrophic methanogens (Methanothermobacter and Methanosarcina) and hydrogen-producing bacteria (Coprothermobacter, Acetomicrobium, and Defluviitoga). Nine major metagenome-assembled genomes (MAGs) associated with the dominant genera were selected to infer their metabolic potentials. Genes related to thermal resistance were widely found in all nine major MAGs, such as the molecular chaperone genes, Clp protease gene, and RNA polymerase genes, which may contribute to their predominance under thermophilic condition. Thermophilic temperatures may increase the hydrogen partial pressure of Coprothermobacter, Acetomicrobium, and Defluviitoga, subsequently altering the primary methanogenesis pathway from acetoclastic pathway to hydrogenotrophic pathway in the TAD. Consequently, genes encoding the hydrogenotrophic methanogenesis pathway were the most abundant in the recovered archaeal MAGs. The potential interaction between hydrogen-producing bacteria and hydrogenotrophic methanogens may play critical roles in TAD processes.


Assuntos
Archaea , Bactérias , Metano , Archaea/genética , Archaea/metabolismo , Bactérias/metabolismo , Bactérias/genética , Anaerobiose , Metano/metabolismo , Filogenia , Reatores Biológicos/microbiologia
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