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1.
Artigo em Inglês | MEDLINE | ID: mdl-34379584

RESUMO

Three highly alkaliphilic bacterial strains designated as A1T, H1T and B1T were isolated from two highly alkaline springs at The Cedars, a terrestrial serpentinizing site. Cells from all strains were motile, Gram-negative and rod-shaped. Strains A1T, H1T and B1T were mesophilic (optimum, 30 °C), highly alkaliphilic (optimum, pH 11) and facultatively autotrophic. Major cellular fatty acids were saturated and monounsaturated hexadecenoic and octadecanoic acids. The genome size of strains A1T, H1T and B1T was 2 574 013, 2 475 906 and 2 623 236 bp, and the G+C content was 66.0, 66.2 and 66.1 mol%, respectively. Analysis of the 16S rRNA genes showed the highest similarity to the genera Malikia (95.1-96.4 %), Macromonas (93.0-93.6 %) and Hydrogenophaga (93.0-96.6 %) in the family Comamonadaceae. Phylogenetic analysis based on 16S rRNA gene and phylogenomic analysis based on core gene sequences revealed that the isolated strains diverged from the related species, forming a distinct branch. Average amino acid identity values of strains A1T, H1T and B1T against the genomes of related members in this family were below 67 %, which is below the suggested threshold for genera boundaries. Average nucleotide identity by blast values and digital DNA-DNA hybridization among the three strains were below 92.0 and 46.6 % respectively, which are below the suggested thresholds for species boundaries. Based on phylogenetic, genomic and phenotypic characterization, we propose Serpentinimonas gen. nov., Serpentinimonas raichei sp. nov. (type strain A1T=NBRC 111848T=DSM 103917T), Serpentinimonas barnesii sp. nov. (type strain H1T= NBRC 111849T=DSM 103920T) and Serpentinimonas maccroryi sp. nov. (type strain B1T=NBRC 111850T=DSM 103919T) belonging to the family Comamonadaceae. We have designated Serpentinimonas raichei the type species for the genus because it is the dominant species in The Cedars springs.


Assuntos
Comamonadaceae , Filogenia , Microbiologia da Água , Técnicas de Tipagem Bacteriana , Composição de Bases , Comamonadaceae/classificação , Comamonadaceae/isolamento & purificação , DNA Bacteriano/genética , Ácidos Graxos/química , Hibridização de Ácido Nucleico , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
2.
Proc Natl Acad Sci U S A ; 110(38): 15336-41, 2013 Sep 17.
Artigo em Inglês | MEDLINE | ID: mdl-24003156

RESUMO

The Cedars, in coastal northern California, is an active site of peridotite serpentinization. The spring waters that emerge from this system feature very high pH, low redox potential, and low ionic concentrations, making it an exceptionally challenging environment for life. We report a multiyear, culture-independent geomicrobiological study of three springs at The Cedars that differ with respect to the nature of the groundwater feeding them. Within each spring, both geochemical properties and microbial diversity in all three domains of life remained stable over a 3-y period, with multiple samples each year. Between the three springs, however, the microbial communities showed considerable differences that were strongly correlated with the source of the serpentinizing groundwater. In the spring fed solely by deep groundwater, phylum Chloroflexi, class Clostridia, and candidate division OD1 were the major taxa with one phylotype in Euryarchaeota. Less-abundant phylotypes include several minor members from other candidate divisions and one phylotype that was an outlier of candidate division OP3. In the springs fed by the mixture of deep and shallow groundwater, organisms close to the Hydrogenophaga within Betaproteobacteria dominated and coexisted with the deep groundwater community members. The shallow groundwater community thus appears to be similar to those described in other terrestrial serpentinizing sites, whereas the deep community is distinctly different from any other previously described terrestrial serpentinizing community. These unique communities have the potential to yield important insights into the development and survival of life in these early-earth analog environments.


Assuntos
Biodiversidade , Ecossistema , Metagenoma/genética , Nascentes Naturais/química , Nascentes Naturais/microbiologia , Asbestos Serpentinas/química , Sequência de Bases , California , Chloroflexi/genética , Cianobactérias/genética , Euryarchaeota/genética , Bactérias Gram-Positivas/genética , Concentração de Íons de Hidrogênio , Dados de Sequência Molecular , Oxirredução , Proteobactérias/genética , RNA Ribossômico 16S/genética , Análise de Sequência de RNA
3.
Environ Microbiol Rep ; 16(1): e13210, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-37950419

RESUMO

The MBES04 strain of Novosphingobium accumulates phenylpropanone monomers as end-products of the etherase system, which specifically and reductively cleaves the ß-O-4 ether bond (a major bond in lignin molecules). However, it does not utilise phenylpropanone monomers as an energy source. Here, we studied the response to the lignin-related perturbation to clarify the physiological significance of its etherase system. Transcriptome analysis revealed two gene clusters, each consisting of four tandemly linked genes, specifically induced by a lignin preparation extracted from hardwood (Eucalyptus globulus) and a ß-O-4-type lignin model biaryl compound, but not by vanillin. The most strongly induced gene was a 2,4'-dihydroxyacetophenone dioxygenase-like protein, which leads to energy production through oxidative degradation. The other cluster was related to multidrug resistance. The former cluster was transcriptionally regulated by a common promoter, where a phenylpropanone monomer acted as one of the effectors responsible for gene induction. These results indicate that the physiological significance of the etherase system of the strain lies in its function as a sensor for lignin fragments. This may be a survival strategy to detect nutrients and gain tolerance to recalcitrant toxic compounds, while the strain preferentially utilises easily degradable aromatic compounds with lower energy demands for catabolism.


Assuntos
Hidrocarbonetos Fluorados , Lignina , Sphingomonadaceae , Lignina/química , Proteínas de Bactérias/genética , Oxirredução , Éteres/química , Éteres/metabolismo , Sphingomonadaceae/genética , Sphingomonadaceae/metabolismo
4.
Nat Commun ; 15(1): 4858, 2024 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-38871712

RESUMO

Serpentinization, a geochemical process found on modern and ancient Earth, provides an ultra-reducing environment that can support microbial methanogenesis and acetogenesis. Several groups of archaea, such as the order Methanocellales, are characterized by their ability to produce methane. Here, we generate metagenomic sequences from serpentinized springs in The Cedars, California, and construct a circularized metagenome-assembled genome of a Methanocellales archaeon, termed Met12, that lacks essential methanogenesis genes. The genome includes genes for an acetyl-CoA pathway, but lacks genes encoding methanogenesis enzymes such as methyl-coenzyme M reductase, heterodisulfide reductases and hydrogenases. In situ transcriptomic analyses reveal high expression of a multi-heme c-type cytochrome, and heterologous expression of this protein in a model bacterium demonstrates that it is capable of accepting electrons. Our results suggest that Met12, within the order Methanocellales, is not a methanogen but a CO2-reducing, electron-fueled acetogen without electron bifurcation.


Assuntos
Metano , Metano/metabolismo , Genoma Arqueal , Proteínas Arqueais/metabolismo , Proteínas Arqueais/genética , Oxirredutases/genética , Oxirredutases/metabolismo , Metagenoma/genética , Filogenia , Acetilcoenzima A/metabolismo , Dióxido de Carbono/metabolismo , Metagenômica
5.
Nat Commun ; 15(1): 568, 2024 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-38278791

RESUMO

Microbes can decompose biodegradable plastics on land, rivers and seashore. However, it is unclear whether deep-sea microbes can degrade biodegradable plastics in the extreme environmental conditions of the seafloor. Here, we report microbial decomposition of representative biodegradable plastics (polyhydroxyalkanoates, biodegradable polyesters, and polysaccharide esters) at diverse deep-sea floor locations ranging in depth from 757 to 5552 m. The degradation of samples was evaluated in terms of weight loss, reduction in material thickness, and surface morphological changes. Poly(L-lactic acid) did not degrade at either shore or deep-sea sites, while other biodegradable polyesters, polyhydroxyalkanoates, and polysaccharide esters were degraded. The rate of degradation slowed with water depth. We analysed the plastic-associated microbial communities by 16S rRNA gene amplicon sequencing and metagenomics. Several dominant microorganisms carried genes potentially encoding plastic-degrading enzymes such as polyhydroxyalkanoate depolymerases and cutinases/polyesterases. Analysis of available metagenomic datasets indicated that these microorganisms are present in other deep-sea locations. Our results confirm that biodegradable plastics can be degraded by the action of microorganisms on the deep-sea floor, although with much less efficiency than in coastal settings.


Assuntos
Plásticos Biodegradáveis , Poli-Hidroxialcanoatos , RNA Ribossômico 16S/genética , Biodegradação Ambiental , Poliésteres/metabolismo , Polissacarídeos
6.
Sci Adv ; 9(25): eadd3584, 2023 06 23.
Artigo em Inglês | MEDLINE | ID: mdl-37343099

RESUMO

Foraminifera, the most ancient known calcium carbonate-producing eukaryotes, are crucial players in global biogeochemical cycles and well-used environmental indicators in biogeosciences. However, little is known about their calcification mechanisms. This impedes understanding the organismal responses to ocean acidification, which alters marine calcium carbonate production, potentially leading to biogeochemical cycle changes. We conducted comparative single-cell transcriptomics and fluorescent microscopy and identified calcium ion (Ca2+) transport/secretion genes and α-carbonic anhydrases that control calcification in a foraminifer. They actively take up Ca2+ to boost mitochondrial adenosine triphosphate synthesis during calcification but need to pump excess intracellular Ca2+ to the calcification site to prevent cell death. Unique α-carbonic anhydrase genes induce the generation of bicarbonate and proton from multiple CO2 sources. These control mechanisms have evolved independently since the Precambrian to enable the development of large cells and calcification despite decreasing Ca2+ concentrations and pH in seawater. The present findings provide previously unknown insights into the calcification mechanisms and their subsequent function in enduring ocean acidification.


Assuntos
Foraminíferos , Água do Mar , Foraminíferos/genética , Foraminíferos/metabolismo , Concentração de Íons de Hidrogênio , Calcificação Fisiológica , Carbonato de Cálcio/metabolismo , Dióxido de Carbono/metabolismo
7.
Appl Microbiol Biotechnol ; 94(4): 1087-94, 2012 May.
Artigo em Inglês | MEDLINE | ID: mdl-22223104

RESUMO

The improvement in electricity generation during the enrichment process of a microbial consortium was analyzed using an air-cathode microbial fuel cell (MFC) repeatedly fed with acetate that was originally inoculated with sludge from an anaerobic digester. The anodic maximum current density produced by the anode biofilm increased from 0.12 mA/cm(2) at day 28 to 1.12 mA/cm(2) at day 105. However, the microbial cell density on the carbon cloth anode increased only three times throughout this same time period from 0.21 to 0.69 mg protein/cm(2), indicating that the biocatalytic activity of the consortium was also enhanced. The microbial activity was calculated to have a per biomass anode-reducing rate of 374 µmol electron g protein(-1) min(-1) at day 28 and 1,002 µmol electron g protein(-1) min(-1) at day 105. A bacterial community analysis of the anode biofilm revealed that the dominant phylotype, which was closely related to the known exoelectrogenic bacterium, Geobacter sulfurreducens, showed an increase in abundance from 32% to 70% of the total microbial cells. Fluorescent in situ hybridization observation also showed the increase of Geobacter-like phylotypes from 53% to 72%. These results suggest that the improvement of microbial current generation in microbial fuel cells is a function of both microbial cell growth on the electrode and changes in the bacterial community highly dominated by a known exoelectrogenic bacterium during the enrichment process.


Assuntos
Fontes de Energia Bioelétrica , Biofilmes/crescimento & desenvolvimento , Eletrodos/microbiologia , Consórcios Microbianos/fisiologia , Acetatos/metabolismo , Bactérias/classificação , Bactérias/isolamento & purificação , Biomassa , Biota , Eletricidade , Hibridização in Situ Fluorescente , Oxirredução , Esgotos/microbiologia
8.
Microorganisms ; 9(9)2021 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-34576847

RESUMO

In this study, a novel electrogenic bacterium denoted as strain NIT-T3 of the genus Desulfuromonas was isolated from a graphene-oxide-reducing enrichment culture that was originally obtained from a mixture of seawater and coastal sand. Strain NIT-T3 utilized hydrogen and various organic acids as electron donors and exhibited respiration using electrodes, ferric iron, nitrate, and elemental sulfur. The strain contained C16:1ω7c, C16:0, and C15:0 as major fatty acids and MK-8, 9, and 7 as the major respiratory quinones. Strain NIT-T3 contained four 16S rRNA genes and showed 95.7% similarity to Desulfuromonasmichiganensis BB1T, the closest relative. The genome was 4.7 Mbp in size and encoded 76 putative c-type cytochromes, which included 6 unique c-type cytochromes (<40% identity) compared to those in the database. Based on the physiological and genetic uniqueness, and wide metabolic capability, strain NIT-T3 is proposed as a type strain of 'Desulfuromonas versatilis' sp. nov.

9.
Water Res ; 205: 117608, 2021 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-34555741

RESUMO

Advances in high-throughput sequencing technologies and bioinformatics approaches over almost the last three decades have substantially increased our ability to explore microorganisms and their functions - including those that have yet to be cultivated in pure isolation. Genome-resolved metagenomic approaches have enabled linking powerful functional predictions to specific taxonomical groups with increasing fidelity. Additionally, related developments in both whole community gene expression surveys and metabolite profiling have permitted for direct surveys of community-scale functions in specific environmental settings. These advances have allowed for a shift in microbiome science away from descriptive studies and towards mechanistic and predictive frameworks for designing and harnessing microbial communities for desired beneficial outcomes. Water engineers, microbiologists, and microbial ecologists studying activated sludge, anaerobic digestion, and drinking water distribution systems have applied various (meta)omics techniques for connecting microbial community dynamics and physiologies to overall process parameters and system performance. However, the rapid pace at which new omics-based approaches are developed can appear daunting to those looking to apply these state-of-the-art practices for the first time. Here, we review how modern genome-resolved metagenomic approaches have been applied to a variety of water engineering applications from lab-scale bioreactors to full-scale systems. We describe integrated omics analysis across engineered water systems and the foundations for pairing these insights with modeling approaches. Lastly, we summarize emerging omics-based technologies that we believe will be powerful tools for water engineering applications. Overall, we provide a framework for microbial ecologists specializing in water engineering to apply cutting-edge omics approaches to their research questions to achieve novel functional insights. Successful adoption of predictive frameworks in engineered water systems could enable more economically and environmentally sustainable bioprocesses as demand for water and energy resources increases.


Assuntos
Microbiota , Água , Reatores Biológicos , Metagenômica , Esgotos
10.
Microb Ecol ; 59(3): 415-27, 2010 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-20024685

RESUMO

Microbial fuel cell (MFC) systems employ the catalytic activity of microbes to produce electricity from the oxidation of organic, and in some cases inorganic, substrates. MFC systems have been primarily explored for their use in bioremediation and bioenergy applications; however, these systems also offer a unique strategy for the cultivation of synergistic microbial communities. It has been hypothesized that the mechanism(s) of microbial electron transfer that enable electricity production in MFCs may be a cooperative strategy within mixed microbial consortia that is associated with, or is an alternative to, interspecies hydrogen (H(2)) transfer. Microbial fermentation processes and methanogenesis in ruminant animals are highly dependent on the consumption and production of H(2)in the rumen. Given the crucial role that H(2) plays in ruminant digestion, it is desirable to understand the microbial relationships that control H(2) partial pressures within the rumen; MFCs may serve as unique tools for studying this complex ecological system. Further, MFC systems offer a novel approach to studying biofilms that form under different redox conditions and may be applied to achieve a greater understanding of how microbial biofilms impact animal health. Here, we present a brief summary of the efforts made towards understanding rumen microbial ecology, microbial biofilms related to animal health, and how MFCs may be further applied in ruminant research.


Assuntos
Fontes de Energia Bioelétrica , Biofilmes , Rúmen/microbiologia , Ruminantes/microbiologia , Fenômenos Fisiológicos da Nutrição Animal , Animais , Biodegradação Ambiental , Fermentação , Hidrogênio , Metano/biossíntese , Oxirredução , Eliminação de Resíduos Líquidos
11.
Appl Environ Microbiol ; 74(8): 2511-7, 2008 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-18310422

RESUMO

The affinity of microbial cells for hydrophobic interfaces is important because it directly affects the efficiency of various bioprocesses, including green biotechnologies. The toluene-degrading bacterium Acinetobacter sp. strain Tol 5 has filamentous appendages and a hydrophobic cell surface, shows high adhesiveness to solid surfaces, and self-agglutinates. A "bald" mutant of this bacterium, strain T1, lacks the filamentous appendages and has decreased adhesiveness but retains a hydrophobic cell surface. We investigated the interaction between T1 cells and an organic solvent dispersed in an aqueous matrix. During a microbial-adhesion-to-hydrocarbon (MATH) test, which is frequently used to measure cell surface hydrophobicity, T1 cells adhered to hexadecane droplet surfaces in a monolayer, whereas wild-type cells aggregated on the droplet surfaces. The adsorbed T1 cells on the hexadecane surfaces hindered the coalescence of the droplets formed by vortexing, stabilizing the emulsion phase. Following the replacement of the aqueous phase with fresh pure water after the MATH test, a proportion of the T1 cells that had adsorbed to the hydrocarbon surface detached during further vortexing, suggesting a reversible adsorption of T1 cells. The final ratio of the adhering cells to the total cells in the detachment test coincided with that in the MATH test. The adhesion of T1 cells to the hydrocarbon surface conformed to the Langmuir adsorption isotherm, which describes reversible monolayer adsorption. Reversible monolayer adsorption should be useful for green technologies employing two-liquid-phase partitioning systems and for bioremediation because it allows effective reaction and transport of hydrophobic substrates at oil-water interfaces.


Assuntos
Acinetobacter/fisiologia , Aderência Bacteriana , Hidrocarbonetos/metabolismo , Interações Hidrofóbicas e Hidrofílicas , Adsorção , Emulsões , Cinética
12.
Appl Environ Microbiol ; 74(23): 7348-55, 2008 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-18836002

RESUMO

An electricity-generating bacterium, Geobacter sulfurreducens PCA, was inoculated into a single-chamber, air-cathode microbial fuel cell (MFC) in order to determine the maximum electron transfer rate from bacteria to the anode. To create anodic reaction-limiting conditions, where electron transfer from bacteria to the anode is the rate-limiting step, anodes with electrogenic biofilms were reduced in size and tests were conducted using anodes of six different sizes. The smallest anode (7 cm(2), or 1.5 times larger than the cathode) achieved an anodic reaction-limiting condition as a result of a limited mass of bacteria on the electrode. Under these conditions, the limiting current density reached a maximum of 1,530 mA/m(2), and power density reached a maximum of 461 mW/m(2). Per-biomass efficiency of the electron transfer rate was constant at 32 fmol cell(-1) day(-1) (178 micromol g of protein(-1) min(-1)), a rate comparable to that with solid iron as the electron acceptor but lower than rates achieved with fumarate or soluble iron. In comparison, an enriched electricity-generating consortium reached 374 micromol g of protein(-1) min(-1) under the same conditions, suggesting that the consortium had a much greater capacity for electrode reduction. These results demonstrate that per-biomass electrode reduction rates (calculated by current density and biomass density on the anode) can be used to help make better comparisons of electrogenic activity in MFCs.


Assuntos
Bactérias/classificação , Bactérias/metabolismo , Eletrodos , Biofilmes , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Eletricidade , Fumaratos/metabolismo , Genes de RNAr , Geobacter/metabolismo , Ferro/metabolismo , Dados de Sequência Molecular , Oxirredução , Filogenia , RNA Bacteriano/genética , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Homologia de Sequência do Ácido Nucleico
13.
BMC Microbiol ; 8: 6, 2008 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-18186940

RESUMO

BACKGROUND: Microbial fuel cells (MFCs) are devices that exploit microorganisms to generate electric power from organic matter. Despite the development of efficient MFC reactors, the microbiology of electricity generation remains to be sufficiently understood. RESULTS: A laboratory-scale two-chamber microbial fuel cell (MFC) was inoculated with rice paddy field soil and fed cellulose as the carbon and energy source. Electricity-generating microorganisms were enriched by subculturing biofilms that attached onto anode electrodes. An electric current of 0.2 mA was generated from the first enrichment culture, and ratios of the major metabolites (e.g., electric current, methane and acetate) became stable after the forth enrichment. In order to investigate the electrogenic microbial community in the anode biofilm, it was morphologically analyzed by electron microscopy, and community members were phylogenetically identified by 16S rRNA gene clone-library analyses. Electron microscopy revealed that filamentous cells and rod-shaped cells with prosthecae-like filamentous appendages were abundantly present in the biofilm. Filamentous cells and appendages were interconnected via thin filaments. The clone library analyses frequently detected phylotypes affiliated with Clostridiales, Chloroflexi, Rhizobiales and Methanobacterium. Fluorescence in-situ hybridization revealed that the Rhizobiales population represented rod-shaped cells with filamentous appendages and constituted over 30% of the total population. CONCLUSION: Bacteria affiliated with the Rhizobiales constituted the major population in the cellulose-fed MFC and exhibited unique morphology with filamentous appendages. They are considered to play important roles in the cellulose-degrading electrogenic community.


Assuntos
Bactérias/metabolismo , Fenômenos Fisiológicos Bacterianos , Biofilmes/crescimento & desenvolvimento , Celulose/metabolismo , Eletroquímica/instrumentação , Bactérias/classificação , Bactérias/genética , Fontes de Energia Bioelétrica , Eletricidade , Eletroquímica/métodos , Eletrodos , Desenho de Equipamento , Hibridização in Situ Fluorescente , RNA Ribossômico 16S/genética , Microbiologia do Solo
14.
Biosci Biotechnol Biochem ; 72(2): 286-94, 2008 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-18256466

RESUMO

Two H-type microbial fuel cells were prepared. The anaerobic chambers were inoculated with rice paddy field soil and fed cellulose as an energy source. In one reactor, the anode and cathode were connected with a wire (closed circuit, CC), while they were not connected in the other reactor (open circuit, OC). The OC reactor actively produced methane. In the CC reactor, however, an electric current of 0.2 to 0.3 mA was constantly generated, and methane production was almost completely suppressed. Electron microscopy revealed that rod-shaped cells with long prosthecae-like filaments were specifically enriched in the CC reactor. Comparisons of 16S rRNA gene clone libraries revealed entirely different phylogenetic compositions in the CC and OC communities; phylotypes related to Rhizobiceae, Desulfovibrio, and Ethanoligenens were specifically enriched in the CC community. The results indicate that electrogenesis resulted in the enrichment of distinctive microbial populations and suppressed methanogenesis from cellulose.


Assuntos
Bactérias/metabolismo , Eletricidade , Metano/biossíntese , Filogenia , Bactérias/classificação , Bactérias/genética , Bactérias/ultraestrutura , Sequência de Bases , Celulose/metabolismo , Cromatografia Gasosa , Cromatografia Líquida de Alta Pressão , Primers do DNA , Microscopia Eletrônica de Varredura , Reação em Cadeia da Polimerase , RNA Ribossômico 16S/genética , Especificidade da Espécie
15.
J Biosci Bioeng ; 105(1): 20-5, 2008 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-18295715

RESUMO

The toluene-degrading bacterium Acinetobacter sp. Tol 5 is highly adhesive to solid surfaces owing to two filamentous cell appendages, namely, anchors and peritrichate fibrils. When growing this bacterium in the presence of a carrier made of polyurethane foam, almost all the cells adhered to the surface of the carrier. In contrast, when Tol 5 cells were grown in the absence of the polyurethane carrier, the cells were suspended as aggregated cells or individually dispersed cells. The aggregated cells possessed the cell appendages and showed an adhesiveness similar to that of cells grown in the presence of the carrier, while the dispersed cells scarcely produced the cell appendages and showed a low level of adhesiveness. The dispersed cells started to adhere to the polyurethane carrier by producing the filamentous appendages within 30 min of the addition of the carrier as a substratum and toluene as a carbon source. Peritrichate fibrils just sprouting and growing anchors longer than 3 microm were observed when the cells started to adhere. This suggests that the presence of surface areas sufficient for adhesion might trigger cell appendage formation in Tol 5 cells for adhesion by increasing the amount of cell contact with the surfaces.


Assuntos
Acinetobacter/fisiologia , Aderência Bacteriana , Fímbrias Bacterianas/fisiologia , Acinetobacter/efeitos dos fármacos , Acinetobacter/ultraestrutura , Aderência Bacteriana/efeitos dos fármacos , Biodegradação Ambiental , Técnicas de Cultura de Células , Fímbrias Bacterianas/ultraestrutura , Poliuretanos/farmacologia , Propriedades de Superfície , Tolueno/metabolismo
16.
Bioresour Technol ; 255: 302-307, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29426790

RESUMO

In bioelectrochemical systems (BESs), electrons are transferred between electrochemically active microbes (EAMs) and conductive materials, such as electrodes, via extracellular electron transfer (EET) pathways, and electrons thus transferred stimulate intracellular catabolic reactions. Catabolic and EET pathways have extensively been studied for several model EAMs, such as Shewanella oneidensis MR-1 and Geobacter sulfurreducens PCA, whereas it is also important to understand the ecophysiology of EAMs in naturally occurring microbiomes, such as those in anode biofilms in microbial fuel cells treating wastewater. Recent studies have exploited metagenomics and metatranscriptomics (meta-omics) approaches to characterize EAMs in BES-associated microbiomes. Here we review recent BES studies that used meta-omics approaches and show that these studies have discovered unexpected features of EAMs and deepened our understanding of functions and behaviors of microbes in BESs. It is desired that more studies will employ meta-omics approaches for advancing our knowledge on microbes in BESs.


Assuntos
Fontes de Energia Bioelétrica , Shewanella , Eletrodos , Transporte de Elétrons , Geobacter
17.
Front Microbiol ; 9: 3141, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30619209

RESUMO

Serpentinization is a process whereby water interacts with reduced mantle rock called peridotite to produce a new suite of minerals (e.g., serpentine), a highly alkaline fluid, and hydrogen. In previous reports, we identified abundance of microbes of the candidate phylum NPL-UPA2 in a serpentinization site called The Cedars. Here, we report the first metagenome assembled genome (MAG) of the candidate phylum as well as the in-situ gene expression. The MAG of the phylum NPL-UPA2, named Unc8, is only about 1 Mbp and its biosynthetic properties suggest it should be capable of independent growth. In keeping with the highly reducing niche of Unc8, its genome encodes none of the known oxidative stress response genes including superoxide dismutases. With regard to energy metabolism, the MAG of Unc8 encodes all enzymes for Wood-Ljungdahl acetogenesis pathway, a ferredoxin:NAD+ oxidoreductase (Rnf) and electron carriers for flavin-based electron bifurcation (Etf, Hdr). Furthermore, the transcriptome of Unc8 in the waters of The Cedars showed enhanced levels of gene expression in the key enzymes of the Wood-Ljungdahl pathway [e.g., Carbon monoxide dehydrogenase /Acetyl-CoA synthase complex (CODH/ACS), Rnf, Acetyl-CoA synthetase (Acd)], which indicated that the Unc8 is an acetogen. However, the MAG of Unc8 encoded no well-known hydrogenase genes, suggesting that the energy metabolism of Unc8 might be focused on CO as the carbon and energy sources for the acetate formation. Given that CO could be supplied via abiotic reaction associated with deep subsurface serpentinization, while available CO2 would be at extremely low concentrations in this high pH environment, CO-associated metabolism could provide advantageous approach. The CODH/ACS in Unc8 is a Bacteria/Archaea hybrid type of six-subunit complex and the electron carriers, Etf and Hdr, showed the highest similarity to those in Archaea, suggesting that archaeal methanogenic energy metabolism was incorporated into the bacterial acetogenesis in NPL-UPA2. Given that serpentinization systems are viewed as potential habitats for early life, and that acetogenesis via the Wood-Ljungdahl pathway is proposed as an energy metabolism of Last Universal Common Ancestor, a phylogenetically distinct acetogen from an early earth analog site may provide important insights in primordial lithotrophs and their habitat.

18.
ISME J ; 12(12): 2844-2863, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30050163

RESUMO

Some microbes can capture energy through redox reactions with electron flow to solid-phase electron acceptors, such as metal-oxides or poised electrodes, via extracellular electron transfer (EET). While diverse oxide minerals, exhibiting different surface redox potentials, are widely distributed on Earth, little is known about how microbes sense and use the minerals. Here we show electrochemical, metabolic, and transcriptional responses of EET-active microbial communities established on poised electrodes to changes in the surface redox potentials (as electron acceptors) and surrounding substrates (as electron donors). Combination of genome-centric stimulus-induced metatranscriptomics and metabolic pathway investigation revealed that nine Geobacter/Pelobacter microbes performed EET activity differently according to their preferable surface potentials and substrates. While the Geobacter/Pelobacter microbes coded numerous numbers of multi-heme c-type cytochromes and conductive e-pili, wide variations in gene expression were seen in response to altering surrounding substrates and surface potentials, accelerating EET via poised electrode or limiting EET via an open circuit system. These flexible responses suggest that a wide variety of EET-active microbes utilizing diverse EET mechanisms may work together to provide such EET-active communities with an impressive ability to handle major changes in surface potential and carbon source availability.


Assuntos
Geobacter/genética , Redes e Vias Metabólicas , Microbiota , Transcriptoma , Carbono/metabolismo , Grupo dos Citocromos c/genética , Grupo dos Citocromos c/metabolismo , Condutividade Elétrica , Eletrodos , Transporte de Elétrons , Geobacter/metabolismo , Heme , Metagenômica , Oxirredução
19.
Genome Announc ; 6(17)2018 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-29700143

RESUMO

Sphingobium sp. strain YG1 is a lignin model dimer-metabolizing bacterium newly isolated from sediment in Kagoshima, Japan, at a depth of 102 m. Here, we report the complete genome nucleotide sequence of strain YG1.

20.
Genome Announc ; 6(12)2018 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-29567747

RESUMO

Altererythrobacter sp. strain B11 is an aromatic monomer-degrading bacterium newly isolated from sediment under the seabed off Kashima, Japan, at a depth of 2,100 m. Here, we report the complete nucleotide sequence of the genome of strain B11.

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