Desulfovibrio subterraneus sp. nov., a mesophilic sulfate-reducing deltaproteobacterium isolated from a deep siliceous mudstone formation.

A novel mesophilic sulfate-reducing bacterium, strain HN2T, was isolated from groundwater sampled from the subsurface siliceous mudstone of the Wakkanai Formation located in Horonobe, Hokkaido, Japan. The bacterium was Gram-negative and vibrio-shaped, and its motility was conferred by a single polar flagellum. Cells had desulfoviridin. Catalase and oxidase activities were not detected. It grew in the temperature range of 25-40 °C (optimum, 35 °C) and pH range of 6.3-8.1 (optimum, pH 7.2-7.6). It used sulfate, thiosulfate, dimethyl sulfoxide, anthraquinone-2,6-disulfonate, Fe3+, and manganese oxide, but not elemental sulfur, nitrite, nitrate, or fumarate as electron acceptors. The strain showed weak growth with sulfite as the electron acceptor. Fermentative growth with pyruvate, lactate and cysteine was observed in the absence of sulfate, but not with malate or fumarate. NaCl was not required, but the strain tolerated up to 40 g l-1. Strain HN2T did not require vitamins. The major cellular fatty acids were iso-C15 : 0 (23.8 %), C18 : 1 ω9t (18.4 %), C18 : 0 (15.0 %), C16 : 0 (14.5 %), and anteiso-C17 :0 (10.1 %). The major respiratory quinone was menaquinone MK-6(H2). The G+C content of the genomic DNA was 56.7 mol%. Based on 16S rRNA gene sequence analysis, the closest phylogenetic relative of strain HN2T is Desulfovibrio psychrotolerans JS1T (97.0 %). Digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values of the strains HN2T and D. psychrotolerans JS1T were 22.2 and 79.8 %, respectively. Based on the phenotypic and molecular genetic evidence, we propose a novel species, D. subterraneus sp. nov. with the type strain HN2T (=DSM 101010T=NBRC 112213T).

Cupidesulfovibrio liaohensis gen. nov., sp. nov., a novel sulphate-reducing bacterium isolated from an oil reservoir and reclassification of Desulfovibrio oxamicus and Desulfovibrio termitidis as Cupidesulfovibrio oxamicus comb. nov. and Cupidesulfovibrio termitidis comb. nov.

A novel sulphate-reducing, Gram-stain-negative, anaerobic strain, isolate XJ01T, recovered from production fluid at the LiaoHe oilfield, PR China, was the subject of a polyphasic study. The isolate together with Desulfovibrio oxamicus NCIMB 9442T and Desulfovibrio termitidis DSM 5308T formed a distinct, well-supported clade in the Desulfovibrionaceae 16S rRNA gene tree. The taxonomic status of the clade was underscored by complementary phenotypic data. The three isolates comprising the clade formed distinct phyletic branches and were distinguished using a combination of physiological features and by low average nucleotide identity and digital DNA-DNA hybridization values. Consequently, it is proposed that isolate XJ01T represents a novel genus and species for which the name Cupidesulfovibrio liaohensis gen. nov., sp. nov. is proposed with the type strain XJ01T (=CGMCC 1.5227T=DSM 107637T). It is also proposed that D. oxamicus and D. termitidis be reclassified as Cupidesulfovibrio oxamicus comb. nov. and Cupidesulfovibrio termitidis comb. nov., respectively.

Desulfovibrio fairfieldensis adhesion on implantable titanium used in odontology: a preliminary study.

The study presented here aimed to assess the ability of Desulfovibrio fairfieldensis bacteria to adhere to and form biofilm on the structure of titanium used in implants. D. fairfieldensis was found in the periodontal pockets in the oral environment, indicating that these bacteria can colonize the implant-bone interface and consequently cause bone infection and implant corrosion. Plates of implantable titanium, of which surfaces were characterized by scanning electronic microscopy and Raman spectroscopy, were immersed in several suspensions of D. fairfieldensis cells containing potassium nitrate on the one hand, and artificial saliva or a sulfato-reducing bacterial culture medium on the other hand. Following various incubation timepoints bacteria were counted in different media to determine their doubling time and titanium samples are checked for and determination of the total number of adhered bacteria and biofilm formation. Adhesion of D. fairfieldensis on titanium occurs at rates ranging from 2.105 to 4.6.106 bacteria h-1cm-2 in the first 18 h of incubation on both native and implantable titanium samples. Following that time, the increase in cell numbers per h and cm2 is attributed to growth in adhered bacteria. After 30 days of incubation in a nutrient-rich medium, dense biofilms are observed forming on the implant surface where bacteria became embedded in a layer of polymers D. fairfieldensis is able of adhering to an implantable titanium surface in order to form a biofilm. Further studies are still necessary, however, to assess whether this adhesion still occurs in an environment containing saliva or serum proteins that may alter the implant surface.

Toxicity of hydrogen sulfide toward sulfate-reducing bacteria Desulfovibrio piger Vib-7.

Sulfate-reducing bacteria (SRB) belonging to the intestinal microbiota are the main producers of hydrogen sulfide and their increasing amount due to the accumulation of this compound in the bowel are involved in the initiation and maintenance of inflammatory bowel disease. The purpose of this experiment is to study the relative toxicity of hydrogen sulfide and survival of Desulfovibrio piger Vib-7 through monitoring: sulfate reduction parameters (sulfate consumption, hydrogen sulfide production, lactate consumption and acetate production) and kinetic parameters of these processes. The research is highlighting the survival of intestinal SRB, D. piger Vib-7 under the influence of different hydrogen sulfide concentrations (1-7 mM). The highest toxicity of H2S was measured in the presence of concentrations higher than 6 mM, where growing was stopped, though metabolic activities were not 100% inhibited. These findings are confirmed by cross correlation and principal component analysis that clearly supported the above mentioned results. The kinetic parameters of bacterial growth and sulfate reduction were inhibited proportionally with increasing H2S concentration. The presence of 5 mM H2S resulted in two times longer lag phase and generation time was eight times longer. Maximum rate of growth and hydrogen production was stopped under 4 mM, emphasizing the H2S toxicity concentrations to be < 4 mM, even for sulfide producing bacteria such as Desulfovibrio. The results are confirming H2S concentrations toxicity toward Desulfovibrio, especially the study novelty should be emphasized where it was found that the exact H2S limits (> 4 mM) toward this bacterial strain inhabiting humans and animals intestine.

Desulfovibrio gilichinskyi sp. nov., a cold-adapted sulfate-reducing bacterium from a Yamal Peninsula cryopeg.

A psychrotolerant non-spore-forming sulfate-reducing bacterium, strain K3ST, was isolated from a Yamal Peninsula cryopeg within permafrost. Strain K3ST grew at subzero temperatures and required Na+ for growth. The new bacterium was able to use lactate, formate, pyruvate, fumarate, alanine, ethanol and molecular hydrogen as electron donors in the presence of sulfate, and used sulfate, sulfite, thiosulfate and elemental sulfur as electron acceptors in the presence of lactate. Fe(III)-citrate and Fe(III)-EDTA were reduced without visible growth. Major polar lipids were рhosphatidylserine, рhosphatidylethanolamine, phospholipids, cardiolipin and aminolipid; major cellular fatty acids were C16 : 1ω7, C16 : 0 and C18 : 1ω7; and the predominant isoprenoid quinone was MK-6 (H2). The genomic DNA G+C content was found to be 42.33 mol%. Phylogenetic analysis showed that the closest relative of the new isolate was Desulfovibrio ferrireducens strain 61T with 97.1 % 16S rRNA gene similarity. In addition, the ANI value between strain K3ST and D. ferrireducens 61T was 82.1 %. On the basis of the genomic and polyphasic taxonomy data of strain K3ST, we conclude that the strain is a representative of a novel species Desulfovibrio gilichinskyi sp. nov. (=VKM B-2877T=DSM 100341T).

Change in the microbial community of saline geothermal fluids amended with a scaling inhibitor: effects of heat extraction and nitrate dosage.

Geothermal plants are often affected by corrosion caused by microbial metabolites such as H2S. In the Bad Blumau (Austria) geothermal system, an increase in microbially produced H2S was observed in the hot (107 °C) and scaling inhibitor-amended saline fluids and in fluids that had cooled down (45 °C). Genetic fingerprinting and quantification revealed the dominance, increasing abundance and diversity of sulfate reducers such as Desulfotomaculum spp. that accompanied the cooling and processing of the geothermal fluids. In addition, a δ34S isotopic signature showed the microbial origin of the H2S that has been produced either chemolithotrophically or chemoorganotrophically. A nitrate addition test in a test pipe as a countermeasure against the microbial H2S formation caused a shift from a biocenosis dominated by bacteria of the phylum Firmicutes to a community of Firmicutes and Proteobacteria. Nitrate supported the growth of nitrate-reducing sulfur-oxidizing Thiobacillus thioparus, which incompletely reduced nitrate to nitrite. The addition of nitrate led to a change in the composition of the sulfate-reducing community. As a result, representatives of nitrate- and nitrite-reducing SRB, such as Desulfovibrio and Desulfonatronum, emerged as additional community members. The interaction of sulfate-reducing bacteria and nitrate-reducing sulfur-oxidizing bacteria (NR-SOB) led to the removal of H2S, but increased the corrosion rate in the test pipe.

Isolation of Desulfovibrio spp. from human gut microbiota using a next-generation sequencing directed culture method.

Desulfovibrio spp. is predominant member of sulphate-reducing bacteria in human gut microbiota. Previous studies indicated that the isolation of Desulfovibrio strains from human faecal samples is very important to study the roles of human intestinal Desulfovibrio spp. in maintaining healthy states or causing diseases, as well as defining their biological characteristics. However, there are very few reports describing the isolation of Desulfovibrio spp. from human faecal samples. In this study, faecal samples were inoculated into various media containing different components. The enriched culture communities were identified using 16S rRNA gene high-throughput sequencing analysis, enabling us to identify the specific components that enable the enrichment of Desulfovibrio. Using this information, we developed five specific media and identified an effective enrichment medium that produced the highest relative abundance of Desulfovibrio in communities cultured from four faecal samples (26·5, 73·5, 44·7 and 77·6% respectively). In addition, the major non-Desulfovibrio genera were identified. Finally, three species of Desulfovibrio, D. desulfuricans, D. piger and D. legallii were isolated, representing the first time that has D. legallii been isolated from a human gastrointestinal source. SIGNIFICANCE AND IMPACT OF THE STUDY: ost of the human intestinal bacteria have not been cultured because of lack of appropriate culture method and appropriate media. Desulfovibrio spp. is associated with several clinical conditions like inflammatory bowel disease, but until now there are very few reports describing the isolation of Desulfovibrio spp. from human faecal samples. In this study, 16S rRNA gene high-throughput sequencing analysis was applied to screen appropriate enrichment media and selective cultivation of Desulfovibrio. This sequencing-based directed culture method described here can be used for the selective cultivation of gut bacteria of interest.

Characterization of Desulfovibrio salinus sp. nov., a slightly halophilic sulfate-reducing bacterium isolated from a saline lake in Tunisia.

A novel slightly halophilic sulfate-reducing bacterium, designated strain P1BSRT, was isolated from water of a saline lake in Tunisia. Strain P1BSRT had motile (single polar flagellum), Gram-negative, rod-shaped, non-spore-forming cells, occurring singly or in pairs. Strain P1BSRT grew at temperatures between 15 and 45 °C (optimum 40 °C), and in a pH range between 6 and 8.5 (optimum pH 6.7). The strain required NaCl for growth (1 % w/v), and tolerated high NaCl concentration (up to 12 % w/v) with an optimum of 3 % (w/v). Sulfate, thiosulfate and sulfite served as terminal electron acceptors, but not elemental sulfur, fumarate, nitrate and nitrite. Strain P1BSRT utilized lactate, pyruvate, formate, d-fructose and glycerol as carbon and energy sources. The main cellular fatty acid was C16 : 0 (50.8 %). The genomic DNA G+C content was 47.7 mol%. Phylogenetic analysis of 16S rRNA gene sequence similarity indicated that strain P1BSRT was affiliated to the genus Desulfovibrio, with the type strains Desulfovibrio salexigens (96.51 %), Desulfovibrio zosterae (95.68 %), Desulfovibrio hydrothermalis (94.81 %) and Desulfovibrio ferrireducens (94.73 %) as its closest phylogenetic relatives. On the basis of genotypic, phenotypic and phylogenetic characteristics, it is proposed to assign strain P1BSRT to a novel species of the genus Desulfovibrio, Desulfovibrio salinus sp. nov. The type strain is P1BSRT (=DSM 101510T=JCM 31065T).

Microbial potential for carbon and nutrient cycling in a geogenic supercritical carbon dioxide reservoir.

Microorganisms catalyze carbon cycling and biogeochemical reactions in the deep subsurface and thus may be expected to influence the fate of injected supercritical (sc) CO2 following geological carbon sequestration (GCS). We hypothesized that natural subsurface scCO2 reservoirs, which serve as analogs for the long-term fate of sequestered scCO2 , harbor a 'deep carbonated biosphere' with carbon cycling potential. We sampled subsurface fluids from scCO2 -water separators at a natural scCO2 reservoir at McElmo Dome, Colorado for analysis of 16S rRNA gene diversity and metagenome content. Sequence annotations indicated dominance of Sulfurospirillum, Rhizobium, Desulfovibrio and four members of the Clostridiales family. Genomes extracted from metagenomes using homology and compositional approaches revealed diverse mechanisms for growth and nutrient cycling, including pathways for CO2 and N2 fixation, anaerobic respiration, sulfur oxidation, fermentation and potential for metabolic syntrophy. Differences in biogeochemical potential between two production well communities were consistent with differences in fluid chemical profiles, suggesting a potential link between microbial activity and geochemistry. The existence of a microbial ecosystem associated with the McElmo Dome scCO2 reservoir indicates that potential impacts of the deep biosphere on CO2 fate and transport should be taken into consideration as a component of GCS planning and modelling.

Desulfovibrio senegalensis sp. nov., a mesophilic sulfate reducer isolated from marine sediment.

Several strains of sulfate-reducing bacteria were isolated from marine sediments recovered from Hann Bay (Senegal). All were related to members of the genus Desulfovibrio. A strictly anaerobic, mesophilic and moderately halophilic strain designated BLaC1T was further characterized. Cells of strain BLaC1T stained Gram-negative and were 0.5 µm wide and 2-4 µm long, motile, rod-shaped and non-spore-forming. The four major fatty acids were anteiso-C15 : 0, iso-C15 : 0, iso-C17 : 0 and anteiso-C17 : 0. Growth was observed from 15 to 45 °C (optimum 40 °C) and at pH 5.5-8 (optimum pH 7.5). The salinity range for growth was 5-65 g NaCl l-1 (optimum 30 g l-1). Yeast extract was required for growth. Strain BLaC1T was able to grow on lactate and acetate in the presence of sulfate as an electron acceptor. Sulfate, thiosulfate and sulfite could serve as terminal electron acceptors, but not fumarate, nitrate or elemental sulfur. The DNA G+C content was 55.8 mol%. 16S rRNA gene sequence analysis assigned strain BLaC1T to the family Desulfovibrionaceae; its closest relative was Desulfovibrio oxyclinae DSM 19275T (93.7 % similarity). On the basis of 16S rRNA gene sequence comparisons and physiological characteristics, strain BLaC1T is proposed as representing a novel species of Desulfovibrio, with the name Desulfovibrio senegalensis sp. nov. The type strain is BLaC1T (=DSM 101509T=JCM 31063T).

Halodesulfovibrio spirochaetisodalis gen. nov. sp. nov. and reclassification of four Desulfovibrio spp.

An antibiotic-producing, obligate anaerobic, Gram-stain-negative, catalase- and oxidase-negative strain (JC271T) was isolated from a marine habitat and identified, based on 16S rRNA gene sequence analysis, as a novel member of the family Desulfovibrionaceae. The closest phylogenetic relatives of strain JC271T were found to be Desulfovibrio marinisediminis C/L2T (99.2 %), Desulfovibrio acrylicus W218T (98.7 %), Desulfovibrio desulfuricans subsp. aestuarii (98.6 %), Desulfovibrio oceani subsp. oceani (98.0 %), Desulfovibrio oceani subsp. galatae (98.0 %) and other members of the genus Desulfovibrio (≤91.9 %). To resolve its full taxonomic position, the genomic sequence of strain JC271T was compared to available genomes of the most closely related phylogenetic members. Average Nucleotide Identity scores and DNA-DNA hybridization values confirmed that strain JC271T represents a novel genomic species. Iso-C17 : 0, iso-C17 : 1ω9c, and iso-C15 : 0 were found to be the major (comprising >10 % of the total present) fatty acids of strain JC271T. Phosphatidylglycerol, phosphatidylethanolamine and unidentified lipids (L1-8) were the polar lipids identified. The G+C content of strain JC271T was 46.2 mol%. Integrated genomic and phenotypic data supported the classification of strain JC271T as a representative of a novel genus, for which the name Halodesulfovibrio spirochaetisodalis gen. nov., sp. nov. is proposed. The type strain is JC271T (=KCTC 15474T=DSM 100016T). It is also proposed that Desulfovibrio acrylicus W218T is the latter heterotypic synonym of Desulfovibrio desulfuricans subsp. aestuarii Sylt 3T. Desulfovibrio desulfuricans subsp. aestuarii Sylt 3T should also be elevated as Halodesulfovibrio aestuarii comb. nov. and Desulfovibrio marinisediminisreclassified as Halodesulfovibrio marinisediminis comb. nov. Desulfovibrio oceani subsp. oceanishould be reclassified as Halodesulfovibrio oceani subsp. oceani comb. nov. and Desulfovibrio oceani subsp. galateae as Halodesulfovibrio oceani subsp. galateae comb. nov.

Distribution of Sulfate-Reducing Communities from Estuarine to Marine Bay Waters.

Estuaries are highly dynamic ecosystems in which freshwater and seawater mix together. Depending on tide and river inflows, particles originating from rivers or from the remobilization of sediments accumulate in the water column. Due to the salinity gradient and the high heterotrophic activity in the estuarine plume, hypoxic and anoxic microniches may form in oxygenated waters, sustaining favorable conditions for resuspended anaerobic microorganisms. In this context, we tested the hypothesis that anaerobic sulfate-reducing prokaryotes may occur in the water column of the Adour River. Using 16S ribosomal RNA (rRNA) and dsrAB-based terminal restriction fragment length polymorphism (T-RFLP) techniques, we characterized total prokaryotic and sulfate-reducing communities along a gradient from estuarine to marine bay waters. Sulfate-reducing prokaryotes were further characterized by the description of dsrB genes and the cultivation of sulfidogenic anaerobic microorganisms. As a result, physical-chemical parameters had a significant effect on water bacterial diversity and community structure along the studied gradient. The concentration of cultured sulfidogenic microorganisms ranged from 1 to 60 × 103 cells l-1 in the water column. Sulfate-reducing prokaryotes occurring in estuarine waters were closely related to microorganisms previously detected in freshwater sediments, suggesting an estuarine origin, mainly by the remobilization of the sediments. In the marine bay station, sediment-derived sulfate-reducing prokaryotes were not cultured anymore, probably due to freshwater dilution, increasing salinity and extended oxic stress. Nevertheless, isolates related to the type strain Desulfovibrio oceani were cultured from the diluted plume and deep marine waters, indicating the occurrence of autochthonous sulfate-reducing bacteria offshore.

Selection for novel, acid-tolerant Desulfovibrio spp. from a closed Transbaikal mine site in a temporal pH-gradient bioreactor.

Almost all the known isolates of acidophilic or acid-tolerant sulphate-reducing bacteria (SRB) belong to the spore-forming genus Desulfosporosinus in the Firmicutes. The objective of this study was to isolate acidophilic/acid-tolerant members of the genus Desulfovibrio belonging to deltaproteobacterial SRB. The sample material originated from microbial mat biomass submerged in mine water and was enriched for sulphate reducers by cultivation in anaerobic medium with lactate as an electron donor. A stirred tank bioreactor with the same medium composition was inoculated with the sulphidogenic enrichment. The bioreactor was operated with a temporal pH gradient, changing daily, from an initial pH of 7.3 to a final pH of 3.7. Among the bacteria in the bioreactor culture, Desulfovibrio was the only SRB group retrieved from the bioreactor consortium as observed by 16S rRNA-targeted denaturing gradient gel electrophoresis. Moderately acidophilic/acid-tolerant isolates belonged to Desulfovibrio aerotolerans-Desulfovibrio carbinophilus-Desulfovibrio magneticus and Desulfovibrio idahonensis-Desulfovibrio mexicanus clades within the genus Desulfovibrio. A moderately acidophilic strain, Desulfovibrio sp. VK (pH optimum 5.7) and acid-tolerant Desulfovibrio sp. ED (pH optimum 6.6) dominated in the bioreactor consortium at different time points and were isolated in pure culture.

Pseudodesulfovibrio indicus gen. nov., sp. nov., a piezophilic sulfate-reducing bacterium from the Indian Ocean and reclassification of four species of the genus Desulfovibrio.

A novel sulfate-reducing bacterium, strain J2T, was isolated from a serpentinized peridotite sample from the Indian Ocean. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain J2T clustered with the genus Desulfovibrio within the family Desulfovibrionaceae, but it showed low similarity (87.95 %) to the type species Desulfovibrio desulfuricans DSM 642T. It was most closely related to Desulfovibrio portus MSL79T (96.96 %), followed by Desulfovibrio aespoeensis Aspo-2T (96.11 %), Desulfovibrio piezophilus C1TLV30T (96.04 %) and Desulfovibrio profundus DSM 11384T (95.17 %). Other available sequences shared less than 93.33 % 16S rRNA gene sequence similarity. Cells were Gram-staining-negative, anaerobic, motile vibrios (2-6×0.4-0.6 µm). Growth was observed at salinities ranging from 0.2 to 6 % (optimum 2.5 %), from pH 5 to 8 (optimum pH 6.5-7) and at temperatures between 9 and 40 °C (optimum 30-35 °C). J2T was piezophilic, growing optimally at 10 MPa (range 0-30 MPa). J2T used lactate, malate, pyruvate, formate and hydrogen as energy sources. Sulfate, thiosulfate, sulfite, fumarate and nitrate were used as terminal electron acceptors. Lactate and pyruvate were fermented. The main fatty acids were iso-C15 : 0, anteiso-C15 : 0, summed feature 9 (iso-C17 : 1ω9c and/or C16 : 0 10-methyl) and iso-C17 : 0. The DNA G+C content of strain J2T was 63.5 mol%. The combined genotypic and phenotypic data show that strain J2T represents a novel species of a novel genus in the family Desulfovibrionaceae, for which the name Pseudodesulfovibrio indicus gen. nov., sp. nov. is proposed, with the type strain J2T (=MCCC 1A01867T = DSM 101483T). We also propose the reclassification of D. piezophilus as Pseudodesulfovibrio piezophilus comb. nov., D. profundus as Pseudodesulfovibrio profundus comb. nov., D. portus as Pseudodesulfovibrio portus comb. nov. and D. aespoeensis as Pseudodesulfovibrio aespoeensis comb. nov.

Characterization of Desulfovibrio biadhensis sp. nov., isolated from a thermal spring.

A novel anaerobic, mesophilic, slightly halophilic sulfate-reducing bacterium, designated strain Khaled BD4(T), was isolated from waters of a Tunisian thermal spring. Cells were vibrio-shaped or sigmoids (5-7×1-1.5 µm) and occurred singly or in pairs. Strain Khaled BD4(T) was Gram-stain-negative, motile and non-sporulated. It grew at 25-45 °C (optimum 37 °C), at pH 5.5-8.3 (optimum pH 7.0) and with 0.5-8% NaCl (optimum 3%). It required vitamins or yeast extract for growth. Sulfate, thiosulfate, sulfite and elemental sulfur served as terminal electron acceptors, but not fumarate, nitrate or nitrite. Strain Khaled BD4(T) utilized H2 in the presence of 2 mM acetate (carbon source), but also lactate, formate, pyruvate and fumarate in the presence of sulfate. Lactate was incompletely oxidized to acetate. Amongst substrates used, only pyruvate was fermented. Desulfoviridin and c-type cytochrome were present. The G+C content of the DNA was 54.6 mol%. The main fatty acids were anteiso -C(15 : 0), iso-C(18 : 0), iso-C(17 : 0) and iso-C(14 : 0). Phylogenetic analysis of the 16S rRNA gene sequence indicated that strain Khaled BD4(T) had Desulfovibrio giganteus DSM 4123(T) (96.7% similarity) as its closest phylogenetic relative. On the basis of 16S rRNA gene sequence comparisons together with genetic and physiological characteristics, strain Khaled BD4(T) is assigned to a novel bacterial species, for which the name Desulfovibrio biadhensis sp. nov. is proposed. The type strain is Khaled BD4(T) ( = DSM 28904(T) = JCM 30146(T)).

Phylogenetic diversity of sulphate-reducing Desulfovibrio associated with three South China Sea sponges.

UNLABELLED: Marine sponges harbour dense and diverse micro-organisms which includes sulphate-reducing bacteria (SRB). SRB are known to play a key role in the cycling of marine elements. However, in contrast to carbon and nitrogen cycling bacteria, SRB associated with marine sponges are largely unexplored. In this study, we explored the phylogenetic diversity of the SRB associated with three shallow-water sponges Arenosclera heroni, Dysidea arenaria and Astrosclera willeyana from the South China Sea by cloning-and-sequencing approach of SRB 16S rRNA gene with specific primers. The results showed that SRB associated with sponges mainly belonged to the genus Desulfovibrio in the class Deltaproteobacteria, i.e. a total of 14 Desulfovibrio-related OTUs were obtained from three sponges. The exception is identical OTUs from different sponges. Each sponge species harboured a unique set of Desulfovibrio OTUs, with only a few shared OTUs observed between species, suggesting different species of Desulfovibrio in different species of sponges. Meanwhile, some Desulfovibrio OTUs had a low similarity (<97%) with related sequences in GenBank and phylogenetic analysis indicating novel Desulfovibrio symbionts in sponges. The results contribute to the overall understanding of the phylogenetic diversity of SRB associated with sponges. SIGNIFICANCE AND IMPACT OF THE STUDY: To date, in contrast to carbon and nitrogen cycling bacteria, sulphate-reducing bacteria (SRB) associated with marine sponges are largely unexplored; little is known about the phylogenetic diversity of SRB in different species of sponges. In the present study, phylogenetically diverse sulphate-reducing Desulfovibrio communities, including potential sponge species-specific and novel SRB, were revealed to be associated with South China Sea demosponges by cloning-and-sequencing approach of SRB 16S rRNA gene.

Biocorrosion of Endodontic Files through the Action of Two Species of Sulfate-reducing Bacteria: Desulfovibrio desulfuricans and Desulfovibrio fairfieldensis.

AIM: This study assessed the biocorrosive capacity of two bacteria: Desulfovibrio desulfuricans and Desulfovibrio fairfieldensis on endodontic files, as a preliminary step in the development of a biopharmaceutical, to facilitate the removal of endodontic file fragments from root canals. MATERIALS AND METHODS: In the first stage, the corrosive potential of the artificial saliva medium (ASM), modified Postgate E medium (MPEM), 2.5 % sodium hypochlorite (NaOCl) solution and white medium (WM), without the inoculation of bacteria was assessed by immersion assays. In the second stage, test samples were inoculated with the two species of sulphur-reducing bacteria (SRB) on ASM and modified artificial saliva medium (MASM). In the third stage, test samples were inoculated with the same species on MPEM, ASM and MASM. All test samples were viewed under an infinite focus Alicona microscope. RESULTS: No test sample became corroded when immersed only in media, without bacteria. With the exception of one test sample between those inoculated with bacteria in ASM and MASM, there was no evidence of corrosion. Fifty percent of the test samples demonstrated a greater intensity of biocorrosion when compared with the initial assays. CONCLUSION: Desulfovibrio desulfuricans and D. fairfieldensis are capable of promoting biocorrosion of the steel constituent of endodontic files. CLINICAL SIGNIFICANCE: This study describes the initial development of a biopharmaceutical to facilitate the removal of endodontic file fragments from root canals, which can be successfully implicated in endodontic therapy in order to avoiding parendodontic surgery or even tooth loss in such events.

[Biodiversity of sulfate-reducing bacteria growing on objects of heating systems].

It was shown that sulfate-reducing bacteria developed on the sections of Kyiv municipal heating systems, which are exploited in conditions of different temperatures. The bacteria were different as to their morphological and physiological properties. The bacteria of Desulfovibrio genus were revealed on the sections, which were exploited at a temperature of 35-40 degrees C and bacteria of Desulfomicrobium and Desulfotomaculum genera were revealed on the sections with a higher temperature such as 60 degrees C. Based on of the 16S rRNA gene analysis data, it was demonstrated that sequences of TC2, TC3 and TC4 clones related to Desulfovibrio sp. DSM 12803 (100% sequence similarity), Desulfotomaculum sp. ECP-C-5 (92% sequence similarity) and Desulfomicrobium baculatum strain DSM 2555 (99% sequence similarity), respectively. The identified bacteria are potentially dangerous for heating systems and can be the agents of microbial corrosion.

Enrichment and characterization of human-associated mucin-degrading microbial consortia by sequential passage.

Mucin is a glycoprotein secreted throughout the mammalian gastrointestinal tract that can support endogenous microorganisms in the absence of complex polysaccharides. While several mucin-degrading bacteria have been identified, the interindividual differences in microbial communities capable of metabolizing this complex polymer are not well described. To determine whether community assembly on mucin is deterministic across individuals or whether taxonomically distinct but functionally similar mucin-degrading communities are selected across fecal inocula, we used a 10-day in vitro sequential batch culture fermentation from three human donors with mucin as the sole carbon source. For each donor, 16S rRNA gene amplicon sequencing was used to characterize microbial community succession, and the short-chain fatty acid profile was determined from the final community. All three communities reached a steady-state by day 7 in which the community composition stabilized. Taxonomic comparisons amongst communities revealed that one of the final communities had Desulfovibrio, another had Akkermansia, and all three shared other members, such as Bacteroides. Metabolic output differences were most notable for one of the donor's communities, with significantly less production of acetate and propionate than the other two communities. These findings demonstrate the feasibility of developing stable mucin-degrading communities with shared and unique taxa. Furthermore, the mechanisms and efficiencies of mucin degradation across individuals are important for understanding how this community-level process impacts human health.

'Candidatus Ancillula trichonymphae', a novel lineage of endosymbiotic Actinobacteria in termite gut flagellates of the genus Trichonympha.

Termite gut flagellates are colonized by host-specific lineages of ectosymbiotic and endosymbiotic bacteria. Previous studies have shown that flagellates of the genus Trichonympha may harbour more than one type of symbiont. Using a comprehensive approach that combined cloning of SSU rRNA genes with fluorescence in situ hybridization and electron microscopy, we investigated the phylogeny and subcellular locations of the symbionts in a variety of Trichonympha species from different termites. The flagellates in Trichonympha Cluster I were the only species associated with 'Endomicrobia', which were located in the posterior part of the cell, confirming previous results. Trichonympha species of Cluster II from the termite genus Incisitermes (family Kalotermitidae) lacked 'Endomicrobia' and were associated with endosymbiotic Actinobacteria, which is highly unusual. The endosymbionts, for which we suggest the name 'Candidatus Ancillula trichonymphae', represent a novel, deep-branching lineage in the Micrococcineae that consists exclusively of clones from termite guts. They preferentially colonized the anterior part of the flagellate host and were highly abundant in all species of Trichonympha Cluster II except Trichonympha globulosa. Here, they were outnumbered by a Desulfovibrio species associated with the cytoplasmic lamellae at the anterior cell pole. Such symbionts are present in both Trichonympha clusters, but not in all species. Unlike the intracellular location reported for the Desulfovibrio symbionts of Trichonympha agilis (Cluster I), the Desulfovibrio symbionts of T. globulosa (Cluster II) were situated in deep invaginations of the plasma membrane that were clearly connected to the exterior of the host cell.