RESUMO
Biodesulfurization (BD) systems that treat sour gas employ mixtures of haloalkaliphilic sulfur-oxidizing bacteria to convert sulfide to elemental sulfur. In the past years, these systems have seen major technical innovations that have led to changes in microbial community composition. Different studies have identified and discussed the microbial communities in both traditional and improved systems. However, these studies do not identify metabolically active community members and merely focus on members' presence/absence. Therefore, their results cannot confirm the activity and role of certain bacteria in the BD system. To investigate the active community members, we determined the microbial communities of six different runs of a pilot-scale BD system. 16S rRNA gene-based amplicon sequencing was performed using both DNA and RNA. A comparison of the DNA- and RNA-based sequencing results identified the active microbes in the BD system. Statistical analyses indicated that not all the existing microbes were actively involved in the system and that microbial communities continuously evolved during the operation. At the end of the run, strains affiliated with Alkalilimnicola ehrlichii and Thioalkalivibrio sulfidiphilus were confirmed as the most active key bacteria in the BD system. This study determined that microbial communities were shaped predominantly by the combination of hydraulic retention time (HRT) and sulfide concentration in the anoxic reactor and, to a lesser extent, by other operational parameters.IMPORTANCEHaloalkaliphilic sulfur-oxidizing bacteria are integral to biodesulfurization (BD) systems and are responsible for converting sulfide to sulfur. To understand the cause of conversions occurring in the BD systems, knowing which bacteria are present and active in the systems is essential. So far, only a few studies have investigated the BD system's microbial composition, but none have identified the active microbial community. Here, we reveal the metabolically active community, their succession, and their influence on product formation.
Assuntos
Bactérias , Sulfetos , RNA Ribossômico 16S/genética , Bactérias/genética , DNA , Enxofre , OxirreduçãoRESUMO
Persistently high marine temperatures are escalating and threating marine biodiversity. The Baltic Sea, warming faster than other seas, is a good model to study the impact of increasing sea surface temperatures. Zostera marina, a key player in the Baltic ecosystem, faces susceptibility to disturbances, especially under chronic high temperatures. Despite the increasing number of studies on the impact of global warming on seagrasses, little attention has been paid to the role of the holobiont. Using an outdoor benthocosm to replicate near-natural conditions, this study explores the repercussions of persistent warming on the microbiome of Z. marina and its implications for holobiont function. Results show that both seasonal warming and chronic warming, impact Z. marina roots and sediment microbiome. Compared with roots, sediments demonstrate higher diversity and stability throughout the study, but temperature effects manifest earlier in both compartments, possibly linked to premature Z. marina die-offs under chronic warming. Shifts in microbial composition, such as an increase in organic matter-degrading and sulfur-related bacteria, accompany chronic warming. A higher ratio of sulfate-reducing bacteria compared to sulfide oxidizers was found in the warming treatment which may result in the collapse of the seagrasses, due to toxic levels of sulfide. Differentiating predicted pathways for warmest temperatures were related to sulfur and nitrogen cycles, suggest an increase of the microbial metabolism, and possible seagrass protection strategies through the production of isoprene. These structural and compositional variations in the associated microbiome offer early insights into the ecological status of seagrasses. Certain taxa/genes/pathways may serve as markers for specific stresses. Monitoring programs should integrate this aspect to identify early indicators of seagrass health. Understanding microbiome changes under stress is crucial for the use of potential probiotic taxa to mitigate climate change effects. Broader-scale examination of seagrass-microorganism interactions is needed to leverage knowledge on host-microbe interactions in seagrasses.
Assuntos
Microbiota , Zosteraceae , Zosteraceae/microbiologia , Raízes de Plantas/microbiologia , Sedimentos Geológicos/microbiologia , Temperatura Alta , Aquecimento Global , Oceanos e Mares , Bactérias/classificação , Bactérias/isolamento & purificação , Estações do Ano , Mudança ClimáticaRESUMO
Biocatalytic copper centers are generally involved in the activation and reduction of dioxygen, with only few exceptions known. Here we report the discovery and characterization of a previously undescribed copper center that forms the active site of a copper-containing enzyme thiocyanate dehydrogenase (suggested EC 1.8.2.7) that was purified from the haloalkaliphilic sulfur-oxidizing bacterium of the genus Thioalkalivibrio ubiquitous in saline alkaline soda lakes. The copper cluster is formed by three copper ions located at the corners of a near-isosceles triangle and facilitates a direct thiocyanate conversion into cyanate, elemental sulfur, and two reducing equivalents without involvement of molecular oxygen. A molecular mechanism of catalysis is suggested based on high-resolution three-dimensional structures, electron paramagnetic resonance (EPR) spectroscopy, quantum mechanics/molecular mechanics (QM/MM) simulations, kinetic studies, and the results of site-directed mutagenesis.
Assuntos
Proteínas de Bactérias/química , Domínio Catalítico , Cobre/química , Ectothiorhodospiraceae/enzimologia , Oxirredutases/química , Bactérias Redutoras de Enxofre/enzimologia , Biocatálise , Espectroscopia de Ressonância de Spin Eletrônica , Concentração de Íons de Hidrogênio , Oxirredução , Oxigênio/química , Enxofre/químicaRESUMO
BACKGROUND: Sponge holobionts (i.e., the host and its associated microbiota) play a key role in the cycling of dissolved organic matter (DOM) in marine ecosystems. On coral reefs, an ecological shift from coral-dominated to algal-dominated ecosystems is currently occurring. Given that benthic corals and macroalgae release different types of DOM, in different abundances and with different bioavailability to sponge holobionts, it is important to understand how the metabolic activity of the host and associated microbiota change in response to the exposure to both DOM sources. Here, we look at the differential gene expression of two sponge holobionts 6 hours after feeding on naturally sourced coral- and macroalgal-DOM using RNA sequencing and meta-transcriptomic analysis. RESULTS: We found a slight, but significant differential gene expression in the comparison between the coral- and macroalgal-DOM treatments in both the high microbial abundance sponge Plakortis angulospiculatus and the low microbial abundance sponge Haliclona vansoesti. In the hosts, processes that regulate immune response, signal transduction, and metabolic pathways related to cell proliferation were elicited. In the associated microbiota carbohydrate metabolism was upregulated in both treatments, but coral-DOM induced further lipid and amino acids biosynthesis, while macroalgal-DOM caused a stress response. These differences could be driven by the presence of distinct organic macronutrients in the two DOM sources and of small pathogens or bacterial virulence factors in the macroalgal-DOM. CONCLUSIONS: This work provides two new sponge meta-transcriptomes and a database of putative genes and genetic pathways that are involved in the differential processing of coral- versus macroalgal-DOM as food source to sponges with high and low abundances of associated microbes. These pathways include carbohydrate metabolism, signaling pathways, and immune responses. However, the differences in the meta-transcriptomic responses of the sponge holobionts after 6 hours of feeding on the two DOM sources were small. Longer-term responses to both DOM sources should be assessed to evaluate how the metabolism and the ecological function of sponges will be affected when reefs shift from coral towards algal dominance.
Assuntos
Antozoários , Microbiota , Poríferos , Aminoácidos , Animais , Antozoários/genética , Recifes de Corais , Matéria Orgânica Dissolvida , Lipídeos , Poríferos/genética , TranscriptomaRESUMO
Biofiltration is a water purification technology playing a pivotal role in producing safe drinking water. This technology attracts many interests worldwide due to its advantages, such as no addition of chemicals, a low energy input, and a high removal efficiency of organic compounds, undesirable taste and odours, and pathogens. The current review describes the microbial ecology of three biofiltration processes that are routinely used in drinking water treatment plants, i.e. (i) rapid sand filtration (RSF), (ii) granular activated carbon filtration (GACF), and (iii) slow sand filtration (SSF). We summarised and compared the characteristics, removal performance, and corresponding (newly revealed) mechanisms of the three biofiltration processes. Specifically, the microbial ecology of the different biofilter processes and the role of microbial communities in removing nutrients, organic compounds, and pathogens were reviewed. Finally, we highlight the limitations and challenges in the study of biofiltration in drinking water production, and propose future perspectives for obtaining a comprehensive understanding of the microbial ecology of biofiltration, which is needed to promote and optimise its further application. KEY POINTS: ⢠Biofilters are composed of complex microbiomes, primarily shaped by water quality. ⢠Conventional biofilters contribute to address safety challenges in drinking water. ⢠Studies may underestimate the active/functional role of microbiomes in biofilters.
Assuntos
Água Potável , Poluentes Químicos da Água , Purificação da Água , Carvão Vegetal , Filtração , Compostos Orgânicos , AreiaRESUMO
In biodesulfurization (BD) at haloalkaline and dO2-limited conditions, sulfide-oxidizing bacteria (SOB) effectively convert sulfide into elemental sulfur that can be used in agriculture as a fertilizer and fungicide. Here we show which bacteria are present in this biotechnological process. 16S rRNA gene amplicon sequencing of biomass from ten reactors sampled in 2018 indicated the presence of 444 bacterial Amplicon Sequence Variants (ASVs). A core microbiome represented by 30 ASVs was found in all ten reactors, with Thioalkalivibrio sulfidiphilus as the most dominant species. The majority of these ASVs are phylogenetically related to bacteria previously identified in haloalkaline BD processes and in natural haloalkaline ecosystems. The source and composition of the feed gas had a great impact on the microbial community composition followed by alkalinity, sulfate, and thiosulfate concentrations. The halophilic SOB of the genus Guyparkeria (formerly known as Halothiobacillus) and heterotrophic SOB of the genus Halomonas were identified as potential indicator organisms of sulfate and thiosulfate accumulation in the BD process. KEY POINTS: ⢠Biodesulfurization (BD) reactors share a core microbiome ⢠The source and composition of the feed gas affects the microbial composition in the BD reactors ⢠Guyparkeria and Halomonas indicate high concentrations of sulfate and thiosulfate in the BD process.
Assuntos
Reatores Biológicos , Microbiota , Reatores Biológicos/microbiologia , Oxirredução , RNA Ribossômico 16S/genética , Sulfatos , SulfetosRESUMO
Sponges possess exceptionally diverse associated microbial communities and play a major role in (re)cycling of dissolved organic matter (DOM) in marine ecosystems. Linking sponge-associated community structure with DOM utilization is essential to understand host-microbe interactions in the uptake, processing, and exchange of resources. We coupled, for the first time, DNA-stable isotope probing (DNA-SIP) with 16S rRNA amplicon sequencing in a sponge holobiont to identify which symbiotic bacterial taxa are metabolically active in DOM uptake. Parallel incubation experiments with the sponge Plakortis angulospiculatus were amended with equimolar quantities of unlabelled (12 C) and labelled (13 C) DOM. Seven bacterial amplicon sequence variants (ASVs), belonging to the phyla PAUC34f, Proteobacteria, Poribacteria, Nitrospirae, and Chloroflexi, were identified as the first active consumers of DOM. Our results support the predictions that PAUC34f, Poribacteria, and Chloroflexi are capable of organic matter degradation through heterotrophic carbon metabolism, while Nitrospirae may have a potential mixotrophic metabolism. We present a new analytical application of DNA-SIP to detect substrate incorporation into a marine holobiont with a complex associated bacterial community and provide new experimental evidence that links the identity of diverse sponge-associated bacteria to the consumption of DOM.
Assuntos
Microbiota , Poríferos , Animais , Bactérias/genética , DNA , Isótopos , RNA Ribossômico 16S/genéticaRESUMO
BACKGROUND: The planetary sulfur cycle is a complex web of chemical reactions that can be microbial-mediated or can occur spontaneously in the environment, depending on the temperature and pH. Inorganic sulfur compounds can serve as energy sources for specialized prokaryotes and are important substrates for microbial growth in general. Here, we investigate dissimilatory sulfur cycling in the brine and sediments of a southwestern Siberian soda lake characterized by an extremely high pH and salinity, combining meta-omics analyses of its uniquely adapted highly diverse prokaryote communities with biogeochemical profiling to identify key microbial players and expand our understanding of sulfur cycling under haloalkaline conditions. RESULTS: Peak microbial activity was found in the top 4 cm of the sediments, a layer with a steep drop in oxygen concentration and redox potential. The majority of sulfur was present as sulfate or iron sulfide. Thiosulfate was readily oxidized by microbes in the presence of oxygen, but oxidation was partially inhibited by light. We obtained 1032 metagenome-assembled genomes, including novel population genomes of characterized colorless sulfur-oxidizing bacteria (SOB), anoxygenic purple sulfur bacteria, heterotrophic SOB, and highly active lithoautotrophic sulfate reducers. Surprisingly, we discovered the potential for nitrogen fixation in a new genus of colorless SOB, carbon fixation in a new species of phototrophic Gemmatimonadetes, and elemental sulfur/sulfite reduction in the "Candidatus Woesearchaeota." Polysulfide/thiosulfate and tetrathionate reductases were actively transcribed by various (facultative) anaerobes. CONCLUSIONS: The recovery of over 200 genomes that encoded enzymes capable of catalyzing key reactions in the inorganic sulfur cycle indicates complete cycling between sulfate and sulfide at moderately hypersaline and extreme alkaline conditions. Our results suggest that more taxonomic groups are involved in sulfur dissimilation than previously assumed.
Assuntos
Archaea/classificação , Archaea/metabolismo , Bactérias/classificação , Bactérias/metabolismo , Lagos/microbiologia , Enxofre/metabolismo , Archaea/genética , Bactérias/genética , Concentração de Íons de Hidrogênio , Lagos/química , Metagenoma , Oxirredução , Filogenia , Salinidade , Sais/química , Sibéria , Enxofre/análiseRESUMO
The existence of sulfate-reducing bacteria (SRB) is a major concern in oil industry due to the detrimental effects of SRB in oil technology. SRB are co-habited with diverse microbial populations in oil fields. The presence of other bacterial groups in oil fields may alter SRB activity in different ways. Therefore, understanding this coexistence may provide insights into problems induced by SRB activity and possible solutions to these problems. To investigate this aspect, not only the presence and abundance of SRB but also bacterial population that coexists with SRB in sulfate-reducing enrichment cultures obtained from the Diyarbakir oil fields in southeast of Turkey was determined by using cultivation- and molecular-based approaches. The most probable number technique (MPN) was used to determine the number of sulfidogenic bacteria in the enrichments. Denaturing gradient gel electrophoresis (DGGE) of polymerase chain reaction-amplified 16S rRNA gene fragments was performed to examine the bacterial diversity of the enrichments. The results demonstrated that the number of sulfidogenic bacteria in the enrichments was low (<103â¯cells/mL). The DGGE analysis indicated that community members belonging to the Firmicutes were more abundant than those of other phyla. Members belonging to SRB mainly consisted of the genera Desulfosporosinus, Desulfovibrio, Thermodesulfovibrio, and Desulfotomaculum. Fermentative bacteria, acetogens, nitrate reducers, and sulfur reducers were also detected in the enrichments. The results of this study not only provide information regarding the diversity of the cultivable portion of the bacterial community that coexists with cultivable SRB, but they also offer insights into the interactions of bacteria in complex microbial communities that inhabit natural environments.
Assuntos
Bactérias/classificação , Bactérias/isolamento & purificação , Biota , Campos de Petróleo e Gás/microbiologia , Bactérias/genética , Bactérias/metabolismo , Técnicas Bacteriológicas , Análise por Conglomerados , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Eletroforese em Gel de Gradiente Desnaturante , Oxirredução , Filogenia , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Sulfatos/metabolismo , TurquiaRESUMO
Cytochrome c oxidases (Coxs) are the basic energy transducers in the respiratory chain of the majority of aerobic organisms. Coxs studied to date are redox-driven proton-pumping enzymes belonging to one of three subfamilies: A-, B-, and C-type oxidases. The C-type oxidases (cbb3 cytochromes), which are widespread among pathogenic bacteria, are the least understood. In particular, the proton-pumping machinery of these Coxs has not yet been elucidated despite the availability of X-ray structure information. Here, we report the discovery of the first (to our knowledge) sodium-pumping Cox (Scox), a cbb3 cytochrome from the extremely alkaliphilic bacterium Thioalkalivibrio versutus. This finding offers clues to the previously unknown structure of the ion-pumping channel in the C-type Coxs and provides insight into the functional properties of this enzyme.
Assuntos
Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Proteobactérias/enzimologia , ATPase Trocadora de Sódio-Potássio/metabolismo , Complexo IV da Cadeia de Transporte de Elétrons/química , Modelos Moleculares , Dados de Sequência Molecular , Conformação ProteicaRESUMO
Sulfidogenic Clostridia and sulfate reducing bacteria (SRB) often cohabit in nature. The presence of these microorganisms can cause microbially influenced corrosion (MIC) of materials in different ways. To investigate this aspect, bacteria were isolated from cooling tower water and used in corrosion tests of galvanized steel. The identity of the isolates was determined by comparative sequence analysis of PCR-amplified 16S rDNA gene fragments, separated by denaturing gradient gel electrophoresis (DGGE). This analysis showed that, in spite of the isolation process, colonies were not pure and consisted of a mixture of bacteria affiliated with Desulfosporosinus meridiei and Clostridium sp. To evaluate the corrosive effect, galvanized steel coupons were incubated with a mixed culture for 4, 8, 24, 72, 96, 168, 360 and 744 h, along with a control set in sterile culture medium only. The corrosion rate was determined by weight loss, and biofilm formation and corroded surfaces were observed by scanning electron microscopy (SEM). Although the sulfide-producing bacterial consortium led to a slight increase in the corrosion of galvanized steel coupons, when compared to the previous studies it can be said that Clostridium sp. can reduce the corrosive effect of the Desulfosporosinus sp. strain.
Assuntos
Bactérias/classificação , Biofilmes/efeitos dos fármacos , Aço/química , Sulfetos/metabolismo , Microbiologia da Água , Ar Condicionado , Bactérias/genética , Bactérias/crescimento & desenvolvimento , Bactérias/metabolismo , Carboidratos/análise , Clostridium/genética , Clostridium/metabolismo , Corrosão , DNA Bacteriano/química , DNA Ribossômico/química , Eletroforese em Gel de Gradiente Desnaturante , Desulfovibrio/genética , Desulfovibrio/metabolismo , Microscopia Eletrônica de Varredura , Peptococcaceae/genética , Peptococcaceae/metabolismo , Reação em Cadeia da Polimerase , RNA Ribossômico 16S/genética , Alinhamento de Sequência , Zinco/análiseRESUMO
A heterotrophic arsenite-oxidizing bacterium, strain 2WW, was isolated from a biofilter treating arsenic-rich groundwater. Comparative analysis of 16S rRNA gene sequences showed that it was closely related (98.7 %) to the alphaproteobacterium Aliihoeflea aesturari strain N8(T). However, it was physiologically different by its ability to grow at relatively low substrate concentrations, low temperatures and by its ability to oxidize arsenite. Here we describe the physiological features of strain 2WW and compare these to its most closely related relative, A. aestuari strain N8(T). In addition, we tested its efficiency to remove arsenic from groundwater in combination with Pf-ferritin. Strain 2WW oxidized arsenite to arsenate between pH 5.0 and 8.0, and from 4 to 30 °C. When the strain was used in combination with a Pf-ferritin-based material for arsenic removal from natural groundwater, the removal efficiency was significantly higher (73 %) than for Pf-ferritin alone (64 %). These results showed that arsenite oxidation by strain 2WW combined with Pf-ferritin-based material has a potential in arsenic removal from contaminated groundwater.
Assuntos
Arsênio/metabolismo , Arsenitos/metabolismo , Ferritinas/metabolismo , Água Subterrânea/química , Água Subterrânea/microbiologia , Phyllobacteriaceae/classificação , Phyllobacteriaceae/metabolismo , Técnicas de Tipagem Bacteriana , Análise por Conglomerados , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Dados de Sequência Molecular , Oxirredução , Phyllobacteriaceae/genética , Phyllobacteriaceae/isolamento & purificação , Filogenia , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , TemperaturaRESUMO
Anaerobic enrichments from hypersaline soda lakes with chitin as substrate yielded five closely related anaerobic haloalkaliphilic isolates growing on insoluble chitin by fermentation at pH 10 and salinities up to 3.5 M. The chitinolytic activity was exclusively cell associated. To better understand the biology and evolutionary history of this novel bacterial lineage, the genome of the type strain ACht1 was sequenced. Analysis of the 2.6 Mb draft genome revealed enzymes of chitin-degradation pathways, including secreted cell-bound chitinases. The reconstructed central metabolism revealed pathways enabling the fermentation of polysaccharides, while it lacks the genes needed for aerobic or anaerobic respiration. The Rnf-type complex, oxaloacetate decarboxylase and sodium-transporting V-type adenosine triphosphatase were identified among putative membrane-bound ion pumps. According to 16S ribosomal RNA analysis, the isolates belong to the candidate phylum Termite Group 3, representing its first culturable members. Phylogenetic analysis using ribosomal proteins and taxonomic distribution analysis of the whole proteome supported a class-level classification of ACht1 most probably affiliated to the phylum Fibribacteres. Based on phylogenetic, phenotypic and genomic analyses, the novel bacteria are proposed to be classified as Chitinivibrio alkaliphilus gen. nov., sp. nov., within a novel class Chitinivibrione.
Assuntos
Fibrobacteres/genética , Genoma Bacteriano , Anaerobiose , Animais , Sequência de Bases , Quitina/metabolismo , Fibrobacteres/classificação , Fibrobacteres/citologia , Concentração de Íons de Hidrogênio , Isópteros/microbiologia , Tipagem Molecular , Filogenia , RNA Ribossômico 16S/genética , Análise de Sequência de DNARESUMO
So far, anaerobic sulfate-dependent acetate oxidation at high pH has only been demonstrated for a low-salt-tolerant syntrophic association of a clostridium 'Candidatus Contubernalis alkalaceticum' and its hydrogenotrophic sulfate-reducing partner Desulfonatronum cooperativum. Anaerobic enrichments at pH 10 inoculated with sediments from hypersaline soda lakes of the Kulunda Steppe (Altai, Russia) demonstrated the possibility of sulfate-dependent acetate oxidation at much higher salt concentrations (up to 3.5 M total Na(+)). The most salt-tolerant purified cultures contained two major components apparently working in syntrophy. The primary acetate-fermenting component was identified as a member of the order Clostridiales forming, together with 'Ca. Contubernalis alkalaceticum', an independent branch within the family Syntrophomonadaceae. A provisional name, 'Ca. Syntrophonatronum acetioxidans', is suggested for the novel haloalkaliphilic clostridium. Two phylotypes of extremely haloalkaliphilic sulfate-reducing bacteria of the genus Desulfonatronospira were identified as sulfate-reducing partners in the acetate-oxidizing cultures under extreme salinity. The dominant phylotype differed from the two species of Desulfonatronospira described so far, whilst a minor component belonged to Desulfonatronum thiodismutans. The results proved that, contrary to previous beliefs, sulfate-dependent acetate oxidation is possible, albeit very slowly, in nearly saturated soda brines.
Assuntos
Acetatos/metabolismo , Deltaproteobacteria/metabolismo , Bactérias Gram-Positivas/metabolismo , Lagos/microbiologia , Consórcios Microbianos , Sulfatos/metabolismo , Análise por Conglomerados , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Deltaproteobacteria/classificação , Deltaproteobacteria/genética , Bactérias Gram-Positivas/classificação , Bactérias Gram-Positivas/genética , Dados de Sequência Molecular , Oxirredução , Filogenia , RNA Ribossômico 16S/genética , Federação Russa , Análise de Sequência de DNARESUMO
A novel nitrite-oxidizing bacterium (NOB), strain Lb(T), was isolated from a nitrifying bioreactor with a high loading of ammonium bicarbonate in a mineral medium with nitrite as the energy source. The cells were oval (lancet-shaped) rods with pointed edges, non-motile, Gram-positive (by staining and from the cell wall structure) and non-spore-forming. Strain Lb(T) was an obligately aerobic, chemolitoautotrophic NOB, utilizing nitrite or formate as the energy source and CO2 as the carbon source. Ammonium served as the only source of assimilated nitrogen. Growth with nitrite was optimal at pH 6.8-7.5 and at 40 °C (maximum 46 °C). The membrane lipids consisted of C20 alkyl 1,2-diols with the dominant fatty acids being 10MeC18 and C(18â:â1)ω9. The peptidoglycan lacked meso-DAP but contained ornithine and lysine. The dominant lipoquinone was MK-8. Phylogenetic analyses of the 16s rRNA gene sequence placed strain Lb(T) into the class Thermomicrobia of the phylum Chloroflexi with Sphaerobacter thermophilus as the closest relative. On the basis of physiological and phylogenetic data, it is proposed that strain Lb(T) represents a novel species of a new genus, with the suggested name Nitrolancea hollandica gen. nov., sp. nov. The type strain of the type species is Lb(T) (â=âDSM 23161(T)â=âUNIQEM U798(T)).
Assuntos
Reatores Biológicos/microbiologia , Chloroflexi/classificação , Nitritos/metabolismo , Filogenia , Composição de Bases , Crescimento Quimioautotrófico , Chloroflexi/genética , Chloroflexi/isolamento & purificação , Chloroflexi/ultraestrutura , DNA Bacteriano/genética , Ácidos Graxos/química , Dados de Sequência Molecular , Países Baixos , Nitrificação , Oxirredução , Peptidoglicano/química , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Vitamina K 2/análogos & derivados , Vitamina K 2/químicaRESUMO
Soda lakes contain high concentrations of sodium carbonates resulting in a stable elevated pH, which provide a unique habitat to a rich diversity of haloalkaliphilic bacteria and archaea. Both cultivation-dependent and -independent methods have aided the identification of key processes and genes in the microbially mediated carbon, nitrogen, and sulfur biogeochemical cycles in soda lakes. In order to survive in this extreme environment, haloalkaliphiles have developed various bioenergetic and structural adaptations to maintain pH homeostasis and intracellular osmotic pressure. The cultivation of a handful of strains has led to the isolation of a number of extremozymes, which allow the cell to perform enzymatic reactions at these extreme conditions. These enzymes potentially contribute to biotechnological applications. In addition, microbial species active in the sulfur cycle can be used for sulfur remediation purposes. Future research should combine both innovative culture methods and state-of-the-art 'meta-omic' techniques to gain a comprehensive understanding of the microbes that flourish in these extreme environments and the processes they mediate. Coupling the biogeochemical C, N, and S cycles and identifying where each process takes place on a spatial and temporal scale could unravel the interspecies relationships and thereby reveal more about the ecosystem dynamics of these enigmatic extreme environments.
Assuntos
Ciclo do Carbono , Lagos/microbiologia , Microbiota , Tolerância ao Sal , Lagos/química , Metano/química , Metano/metabolismo , Ciclo do Nitrogênio , Enxofre/química , Enxofre/metabolismoRESUMO
Biotic and abiotic factors favoring Accelerated Low Water Corrosion (ALWC) on harbor steel structures remain unclear warranting their study under controlled experimental tidal conditions. Initial stimulation of marine microbial consortia by a pulse of organic matter resulted in localized corrosion and the highest corrosion rates (up to 12-times higher than non-stimulated conditions) in the low water zone, persisting after nine months exposure to natural seawater. Correlations between corrosion severity and the abundance and composition of metabolically active sulfate-reducing bacteria (SRB) indicated the importance and persistence of specific bacterial populations in accelerated corrosion. One phylotype related to the electrogenic SRB Desulfopila corrodens appeared as the major causative agent of the accelerated corrosion. The similarity of bacterial populations related to sulfur and iron cycles, mineral and tuberculation with those identified in ALWC support the relevance of experimental simulation of tidal conditions in the management of steel corrosion exposed to harbor environments.
Assuntos
Incrustação Biológica , Água do Mar/microbiologia , Aço , Movimentos da Água , Organismos Aquáticos/fisiologia , Corrosão , Modelos TeóricosRESUMO
The sulfur cycle is a complex biogeochemical cycle characterized by the high variability in the oxidation states of sulfur. While sulfur is essential for life processes, certain sulfur compounds, such as hydrogen sulfide, are toxic to all life forms. Micro-organisms facilitate the sulfur cycle, playing a prominent role even in extreme environments, such as soda lakes, acid mine drainage sites, hot springs, and other harsh habitats. The activity of these micro-organisms presents unique opportunities for mitigating sulfur-based pollution and enhancing the recovery of sulfur and metals. This review highlights the application of sulfur-oxidizing and -reducing micro-organisms in environmental biotechnology through three illustrative examples. Additionally, it discusses the challenges, recent trends, and prospects associated with these applications.
Assuntos
Biotecnologia , Enxofre , Biotecnologia/métodos , Enxofre/metabolismo , Oxirredução , Bactérias/metabolismo , Biodegradação AmbientalRESUMO
The demand for safe drinking water is constantly challenged by increasing biohazards. One widely used solution is implementing indoor-operated slow sand filtration (SSF) as one of the final barriers in water production. SSF has gained popularity due to its low energy consumption and efficient removal of biohazards, especially microorganisms, without using chemicals. SSF involves both physical-chemical and biological removal, particularly in the "Schmutzdecke", which is a biofilm-like layer on the sand bed surface. To achieve the optimal performance of SSF, a systematic understanding of the influence of SSF operating parameters on the Schmutzdecke development and filter filtration performance is required. Our study focused on three operational parameters, i.e., sand material, sand size, and the addition of an inoculum (suspension of matured Schmutzdecke), on the mini-scale filters. The effects of these parameters on the Schmutzdecke development and SSF removal performance were studied by biochemical analyses and 16S amplicon sequencing, together with spiking experiments with Escherichia coli (E. coli) in the mini-scale filters. Our results indicate that the mini-scale filters successfully developed Schmutzdeckes and generated bacterial breakthrough curves efficiently. The sand size and material were found to have an impact on Schmutzdecke's development. The addition of inoculum to new filters did not induce significant changes in the microbial community composition of the Schmutzdecke, but we observed positive effects of faster Schmutzdecke development and better removal performance in some inoculated filters. Our study highlights the value of mini-scale filters for SSF studies, which provide insights into Schmutzdecke microbial ecology and bacterial removal with significantly reduced requirements of materials and effort as compared to larger-scale filters. We found that operational parameters have a greater impact on the Schmutzdecke biochemical characteristics and removal performances than on the microbial community composition. This suggests that Schmutzdecke characteristics may provide more reliable predictors of SSF removal performance, which could help to improve safe drinking water production.
RESUMO
Here, we present the draft genome sequence of Alteromonas gracilis strain J4, isolated from the green macroalga Caulerpa prolifera. The draft genome is 4,492,914 bp in size and contains 4,719 coding DNA sequences, 67 tRNAs, and 16 rRNA-coding genes. Strain J4 may exhibit host growth-promoting properties.