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Haloalkaliphilic chemolithoautotrophic sulfur-oxidizing bacteria belonging to the genus Thioalkalivibrio are highly abundant in microbial communities found in soda lakes and dominant in full-scale bioreactors removing sulfide from industrial waste gases. Despite certain soda lakes being remote and unaffected by anthropogenic activities, haloalkaliphilic microorganisms, including Thioalkalivibrio strains, possess various antibiotic resistance genes. In this study, we investigated the impact of the antibiotic ampicillin on a co-culture of two Thioalkalivibrio species, Tv. thiocyanoxidans ARh2T and Tv. versutus AL2T, both experimentally and through in silico analysis of antibiotic resistance. Cell growth dynamics were monitored over time at increasing ampicillin concentrations using rep- and qPCR. Within ten days after the addition of ampicillin, the co-culture transitioned from a Tv. thiocyanoxidans ARh2T-dominated to a stable Tv. versutus AL2T-dominated culture. This shift was attributed to Tv. versutus AL2T displaying a lower susceptibility to ampicillin, making it more competitive. These results emphasize the potential implications of antibiotic pressure on microbial communities, where a resistant species can outcompete a stable co-culture. This study presents the first evidence of such dynamics in haloalkaliphilic chemolithoautotrophs. By understanding the antibiotic resistance and the competitive dynamics of haloalkaliphilic bacteria like Thioalkalivibrio, we can gain insights into their behaviour and stress response., BT/Environmental Biotechnology

Sclerolinum annulatus n. sp. (Annelida: Siboglinidae) is described based on specimens collected from soft sediment of the Haima cold seep in the South China Sea. Morphologically, S. annulatus n. sp. is distinct in having a tube with transverse rings and a forepart (i.e., anterior region) containing one arched row of elongated plaques on both sides of the dorsal furrow. Genome skimming, assembly, and annotation produced a nearly complete mitogenome of S. annulatus n. sp. with 15,553 bp nucleotides that encodes 13 protein-coding genes, two rRNA, and 22 tRNA. Phylogenetic analyses based on the mitochondrial cytochrome c oxidase I (cox1) gene and a concatenated dataset comprising the mitochondrial cox1 and 16S rRNA genes along with the nuclear 18S rRNA gene both strongly support the placement of S. annulatus n. sp. in the genus Sclerolinum Southward, 1961. Based on cox1, S. annulatus n. sp. is most closely related to an undescribed siboglinid from off Kushiro in Japan (“Pogonophora” sp. Kushiro-SK-2003). Transmission electron microscopy, microbial 16S rRNA amplicon sequencing, phylogenetic reconstruction, and stable isotope analyses together indicate that S. annulatus n. sp. hosts a single phylotype of sulfur-oxidizing endosymbionts. Copyright © 2022 Xu, Sun, Wang, Sen, Qian and Qiu.

Sclerolinum annulatus n. sp. (Annelida: Siboglinidae) was described based on specimens collected from soft sediment of the Haima cold seep in the South China Sea. Morphologically, S. annulatus n. sp. is distinctive in having a tube with transverse rings and a forepart (i.e., anterior region) containing one arched row of elongated plaques on both sides of the dorsal furrow. Genome skimming, assembly, and annotation produced a nearly complete mitogenome of S. annulatus n. sp. with 15,553 bp nucleotides that encodes 13 protein-coding genes, two rRNA, and 22 tRNA. Phylogenetic analyses based on the mitochondrial cytochrome c oxidase I (cox1) gene and a concatenated dataset comprising the mitochondrial cox1 and 16S rRNA genes and the nuclear 18S rRNA gene both strongly support the placement of S. annulatus n. sp. in the genus Sclerolinum Southward, 1961. Based on cox1, S. annulatus n. sp. is most closely related to an undescribed siboglinid from off Kushiro in Japan (“Pogonophora” sp. Kushiro-SK-2003). Transmission electron microscopy, microbial 16S rRNA amplicon sequencing, phylogenetic reconstruction, and stable isotope analyses together indicate that S. annulatus n. sp. hosts a single phylotype of sulfur-oxidizing endosymbionts.

A novel sulfur-oxidizing bacterium, strain Am19(T), was isolated from sediment of a brackish lake. Strain Am19(T) grew chemolithoautotrophically on inorganic sulfur compounds, and heterotrophic growth was not observed. Cells were rod-shaped with length of 1.1-3.0 mu m and diameter of 0.5-0.8 mu m. Growth was observed at 5-37 degrees C with an optimum growth temperature of 30 degrees C. The pH range for growth was 5.6-8.5 with an optimum pH of 6.6-7.0. Major fatty acids were summed feature 3 (C-16: 1 omega 7c and/or C-16: 1 omega 6c), summed feature 8 (C-18: 1 omega 7c and/or C-18: 1 omega 6c) and C-16: 0. The sole respiratory quinone was ubiquinone-8. The complete genome of strain Am19(T) is composed of a circular chromosome with length of 2.5 Mbp and G + C content of 42.7 mol%. Phylogenetic analysis based on genomic data indicated that strain Am19(T) belongs to the genus Thiomicrorhabdus but is distinct from any existing species. Analysis of the 16S rRNA gene supported creation of a new species to accommodate strain Am19(T). On the basis of genomic and phenotypic characteristics, strain Am19(T) (= NBRC 114602( T) = BCRC 81336( T)) is proposed as the type strain of a new species, with name of Thiomicrorhabdus immobilis sp. nov.

A novel chemolithoautotrophic bacterium, strain H1576(T), was isolated from water of a brackish lake. Strain H1576(T) grew aerobically on inorganic sulfur compounds. Hydrogen gas did not support autotrophic growth, and heterotrophic growth was not observed. Cells were rod shaped, motile, 1.5-2.7 mu m in length and 0.6-0.7 mu m in width. Growth was observed at 3-22 degrees C with an optimum growth temperature of 13-15 degrees C. The pH range for growth was 6.0-7.4 with an optimum pH of 6.6-6.8. Major fatty acids were summed feature 3 (C-16: 1 omega 7c and/or C-16: 1 omega 6c). The complete genome of strain H1576(T) consists of a circular chromosome and a plasmid, with total length of 2.8 Mbp and G+C content of 46.4 mol%. Phylogenetic analyses indicated that strain H1576(T) belongs to the genus Sulfurimonas but distinct from representatives of existing species. On the basis of genomic and phenotypic characteristics, a new species named Sulfurimonas aquatica sp. nov. is proposed with the type strain of strain H1576(T) (= BCRC 81254(T) = JCM 35004(T)).

A novel sulfur-oxidizing bacterium, strain Am19(T), was isolated from sediment of a brackish lake. Strain Am19(T) grew chemolithoautotrophically on inorganic sulfur compounds, and heterotrophic growth was not observed. Cells were rod-shaped with length of 1.1-3.0 mu m and diameter of 0.5-0.8 mu m. Growth was observed at 5-37 degrees C with an optimum growth temperature of 30 degrees C. The pH range for growth was 5.6-8.5 with an optimum pH of 6.6-7.0. Major fatty acids were summed feature 3 (C-16: 1 omega 7c and/or C-16: 1 omega 6c), summed feature 8 (C-18: 1 omega 7c and/or C-18: 1 omega 6c) and C-16: 0. The sole respiratory quinone was ubiquinone-8. The complete genome of strain Am19(T) is composed of a circular chromosome with length of 2.5 Mbp and G + C content of 42.7 mol%. Phylogenetic analysis based on genomic data indicated that strain Am19(T) belongs to the genus Thiomicrorhabdus but is distinct from any existing species. Analysis of the 16S rRNA gene supported creation of a new species to accommodate strain Am19(T). On the basis of genomic and phenotypic characteristics, strain Am19(T) (= NBRC 114602( T) = BCRC 81336( T)) is proposed as the type strain of a new species, with name of Thiomicrorhabdus immobilis sp. nov.

Strains J5B(T) and M52(T) are facultatively autotrophic sulfur-oxidizing bacteria isolated from a microbial mat from a hot spring. They were isolated and partially characterized in previous studies, as facultative anaerobes which use nitrate as electron acceptor. In this study, additional characterizations were made to determine their taxonomic status. In both strains, major cellular fatty acids were C-16:1 (C-16:1 omega 7c and/or C-16:1 omega 6c) and C-16:0. Their chemolithoautotrophic growth was supported by thiosulfate and elemental sulfur. They used some organic acids as growth substrates. Their 16S rRNA gene sequences indicated the highest sequence identities to species in the family Sterolibacteriaceae, but the identities were 95% or lower. Phylogenetic analysis indicated that these strains do not belong to any existing genera. Values of average nucleotide identity and digital DNA-DNA hybridization between strains J5B(T) and M52(T) were 87.93% and 34.3%, respectively. On the basis of phenotypic and genomic characteristics, Sulfuricystis multivorans gen. nov. sp. nov., and Sulfuricystis thermophila sp. nov. are proposed, with type strains of J5B(T) and M52(T), respectively. An emended description of the genus Rugosibacter is also proposed, for its reclassification to the family Sterolibacteriaceae.

Strains J5B(T) and M52(T) are facultatively autotrophic sulfur-oxidizing bacteria isolated from a microbial mat from a hot spring. They were isolated and partially characterized in previous studies, as facultative anaerobes which use nitrate as electron acceptor. In this study, additional characterizations were made to determine their taxonomic status. In both strains, major cellular fatty acids were C-16:1 (C-16:1 omega 7c and/or C-16:1 omega 6c) and C-16:0. Their chemolithoautotrophic growth was supported by thiosulfate and elemental sulfur. They used some organic acids as growth substrates. Their 16S rRNA gene sequences indicated the highest sequence identities to species in the family Sterolibacteriaceae, but the identities were 95% or lower. Phylogenetic analysis indicated that these strains do not belong to any existing genera. Values of average nucleotide identity and digital DNA-DNA hybridization between strains J5B(T) and M52(T) were 87.93% and 34.3%, respectively. On the basis of phenotypic and genomic characteristics, Sulfuricystis multivorans gen. nov. sp. nov., and Sulfuricystis thermophila sp. nov. are proposed, with type strains of J5B(T) and M52(T), respectively. An emended description of the genus Rugosibacter is also proposed, for its reclassification to the family Sterolibacteriaceae.

A novel chemolithoautotrophic bacterium, strain H1576(T), was isolated from water of a brackish lake. Strain H1576(T) grew aerobically on inorganic sulfur compounds. Hydrogen gas did not support autotrophic growth, and heterotrophic growth was not observed. Cells were rod shaped, motile, 1.5-2.7 mu m in length and 0.6-0.7 mu m in width. Growth was observed at 3-22 degrees C with an optimum growth temperature of 13-15 degrees C. The pH range for growth was 6.0-7.4 with an optimum pH of 6.6-6.8. Major fatty acids were summed feature 3 (C-16: 1 omega 7c and/or C-16: 1 omega 6c). The complete genome of strain H1576(T) consists of a circular chromosome and a plasmid, with total length of 2.8 Mbp and G+C content of 46.4 mol%. Phylogenetic analyses indicated that strain H1576(T) belongs to the genus Sulfurimonas but distinct from representatives of existing species. On the basis of genomic and phenotypic characteristics, a new species named Sulfurimonas aquatica sp. nov. is proposed with the type strain of strain H1576(T) (= BCRC 81254(T) = JCM 35004(T)).

Sclerolinum annulatus n. sp. (Annelida: Siboglinidae) was described based on specimens collected from soft sediment of the Haima cold seep in the South China Sea. Morphologically, S. annulatus n. sp. is distinctive in having a tube with transverse rings and a forepart (i.e., anterior region) containing one arched row of elongated plaques on both sides of the dorsal furrow. Genome skimming, assembly, and annotation produced a nearly complete mitogenome of S. annulatus n. sp. with 15,553 bp nucleotides that encodes 13 protein-coding genes, two rRNA, and 22 tRNA. Phylogenetic analyses based on the mitochondrial cytochrome c oxidase I (cox1) gene and a concatenated dataset comprising the mitochondrial cox1 and 16S rRNA genes and the nuclear 18S rRNA gene both strongly support the placement of S. annulatus n. sp. in the genus Sclerolinum Southward, 1961. Based on cox1, S. annulatus n. sp. is most closely related to an undescribed siboglinid from off Kushiro in Japan (“Pogonophora” sp. Kushiro-SK-2003). Transmission electron microscopy, microbial 16S rRNA amplicon sequencing, phylogenetic reconstruction, and stable isotope analyses together indicate that S. annulatus n. sp. hosts a single phylotype of sulfur-oxidizing endosymbionts.

Biochemical oxidation and reduction are the principle of biological water and wastewater treatment, in which electron donor and/or acceptor shall be provided. Elemental sulfur (S0) as a non-toxic and easily available material with low price, possesses both reductive and oxidative characteristics, suggesting that it is a suitable material for water and wastewater treatment. Recent advanced understanding of S0-respiring microorganisms and their metabolism further stimulated the development of S0-based technologies. As such, S0-based biotechnologies have emerged as cost-effective and attractive alternatives to conventional biological methods for water and wastewater treatment. For instance, S0-driven autotrophic denitrification substantially lower the operational cost for nitrogen removal from water and wastewater, compared to the conventional process with exogenous carbon source supplementation. The introduction of S0 can also avoid secondary pollution commonly caused by overdose of organic carbon. S0 reduction processes cost-effectively mineralize organic matter with low sludge production. Biological sulfide production using S0 as electron acceptor is also an attractive technology for metal-laden wastewater treatment, e.g. acid mine drainage. This paper outlines an overview of the fundamentals, characteristics and advances of the S0-based biotechnologies and highlights the functional S0-related microorganisms. In particular, the mechanisms of microorganisms accessing insoluble S0 and feasibility to improve S0 bio-utilization efficiency are critically discussed. Additionally, the research knowledge gaps, current process limitations, and required further developments are identified and discussed. © 2021 Elsevier Ltd

Biochemical oxidation and reduction are the principle of biological water and wastewater treatment, in which electron donor and/or acceptor shall be provided. Elemental sulfur (S0) as a non-toxic and easily available material with low price, possesses both reductive and oxidative characteristics, suggesting that it is a suitable material for water and wastewater treatment. Recent advanced understanding of S0-respiring microorganisms and their metabolism further stimulated the development of S0-based technologies. As such, S0-based biotechnologies have emerged as cost-effective and attractive alternatives to conventional biological methods for water and wastewater treatment. For instance, S0-driven autotrophic denitrification substantially lower the operational cost for nitrogen removal from water and wastewater, compared to the conventional process with exogenous carbon source supplementation. The introduction of S0 can also avoid secondary pollution commonly caused by overdose of organic carbon. S0 reduction processes cost-effectively mineralize organic matter with low sludge production. Biological sulfide production using S0 as electron acceptor is also an attractive technology for metal-laden wastewater treatment, e.g. acid mine drainage. This paper outlines an overview of the fundamentals, characteristics and advances of the S0-based biotechnologies and highlights the functional S0-related microorganisms. In particular, the mechanisms of microorganisms accessing insoluble S0 and feasibility to improve S0 bio-utilization efficiency are critically discussed. Additionally, the research knowledge gaps, current process limitations, and required further developments are identified and discussed. © 2021 Elsevier Ltd

The use of microorganisms and their products for the extraction of metals from low grade ores has proven overtime to be more economically viable than other extractive metallurgical processes such as pyrometallurgy. However, the most extensively studied microorganisms for bioleaching are the acidophilic Sulfur and/or Iron-oxidizing chemolithotrophs that are able to catalyze mineral dissolution at low pH. The use of acidophilic bacteria for bioleaching leads to the acidification of the environment as these activities are usually performed at pH ≤ 2. This could have a negative impact on the environment. We hereby propose the use of (halo)alkaliphilic and/or marine sulphur-oxidising microorganisms that live at less acidic, neutral or alkaline conditions for the bioleaching of metals from mining waste. This will prevent the acidification of the environment and save fresh water, as this bioleaching approach could be applicable in seawater. Bioleaching results with Thioclava electrotropha and Thioclava pacifica autotrophs seem promising, as up to 30% Co and 10% Cu, Pb, Zn, Cd, As, K and Mn were solubilised from a fresh waste rock sample. To optimize the bioleaching process, the interaction of these microorganisms with minerals will be studied. The tailing residues cleaned via this approach will be analyzed for subsequent valorization into various circular-economy applications such as inorganic polymers, green cements and ceramics.

The global demand for various metals has greatly increased over the past few years and this demand is envisaged to double over the next coming decades. The extractive waste residue (tailings) by the EU mining industries is a large waste stream and could constitute various environmental hazards such as acid mine drainage, especially when poorly managed. Reprocessing of these tailings could be a significant source of valuable metals and could alleviate environmental risks. This calls for a cost-effective metal mining technology with minimal damaging effect to the environment. We hereby propose the use of (halo)alkaliphilic and/or marine sulfur-oxidizing bacteria that live at neutral to alkaline conditions for the bioleaching of elements from these tailings. This will prevent the acidification of the environment, which is the case when bioleaching with acidophilic bacteria. In addition, this bioleaching approach which could be applicable in seawater is beneficial as fresh water could be saved.

The global demand for various metals has greatly increased over the past few years and this demand is envisaged to double over the next coming decades. The extractive waste residue (tailings) by the EU mining industries is a large waste stream and could constitute various environmental hazards such as acid mine drainage, especially when poorly managed. Reprocessing of these tailings could be a significant source of valuable metals and could alleviate environmental risks. This calls for a cost-effective metal mining technology with minimal damaging effect to the environment. We hereby propose the use of (halo)alkaliphilic and/or marine sulfur-oxidizing bacteria that live at neutral to alkaline conditions for the bioleaching of elements from these tailings. This will prevent the acidification of the environment, which is the case when bioleaching with acidophilic bacteria. In addition, this bioleaching approach which could be applicable in seawater is beneficial as fresh water could be saved.

The use of microorganisms and their products for the extraction of metals from low grade ores has proven overtime to be more economically viable than other extractive metallurgical processes such as pyrometallurgy. However, the most extensively studied microorganisms for bioleaching are the acidophilic Sulfur and/or Iron-oxidizing chemolithotrophs that are able to catalyze mineral dissolution at low pH. The use of acidophilic bacteria for bioleaching leads to the acidification of the environment as these activities are usually performed at pH ≤ 2. This could have a negative impact on the environment. We hereby propose the use of (halo)alkaliphilic and/or marine sulphur-oxidising microorganisms that live at less acidic, neutral or alkaline conditions for the bioleaching of metals from mining waste. This will prevent the acidification of the environment and save fresh water, as this bioleaching approach could be applicable in seawater. Bioleaching results with Thioclava electrotropha and Thioclava pacifica autotrophs seem promising, as up to 30% Co and 10% Cu, Pb, Zn, Cd, As, K and Mn were solubilised from a fresh waste rock sample. To optimize the bioleaching process, the interaction of these microorganisms with minerals will be studied. The tailing residues cleaned via this approach will be analyzed for subsequent valorization into various circular-economy applications such as inorganic polymers, green cements and ceramics.

The biogenic production of toxic H2S gas in sulfate-rich oil sands tailings ponds is associated with strong environmental concerns. Beside precipitation into sulfide minerals and chemical re-oxidation, microbial sulfur oxidation may catalyze sulfide re-cycling but potentially contributes to acid rock drainage (ARD) generation. To evaluate the microbial potential for sulfur oxidation, we conducted a microcosm-based pilot study with tailings of an active pond. Incubations were performed under oxic and anoxic conditions, with and without KNO3 as an electron acceptor and thiosulfate as a common substrate for microbial sulfur oxidation. The highest potentials of sulfur oxidation occurred in oxic assays (1.21 mmol L−1 day−1). Under anoxic conditions, rates were significantly lower and dominated by chemical transformation (0.09 mmol L−1 day−1; p < 0.0001). The addition of KNO3 to anoxic incubations increased microbial thiosulfate oxidation 2.5-fold (0.23 mmol L−1 day−1; p = 0.0474), with complete transformation to SO42− coupled to NO3− consumption, pointing to the activity of sulfur-oxidizing bacteria (SOB) under nitrate-reducing conditions. Importantly, in the presence of KNO3, a decrease in sedimentary sulfides was associated with an increase in S0, which indicates the potential for microbially mediated oxidation of sulfide minerals and ARD generation. Furthermore, the comparative analysis of sediments from other anthropogenic aquatic habitats demonstrated high similarities with respect to viable SOB counts and corresponding activity rates.

Elemental sulfur-driven autotrophic denitrification (S0dAD) was applied in a packed-bed reactor to remove residual nitrogen from raw mature landfill leachate after partial nitritation and anaerobic ammonium oxidation (anammox) (PN/A) pretreatment. The performance and stability of S0dAD were evaluated with different NOx− (nitrate and nitrite) loadings and hydraulic retention time (HRT) at 15–28 °C over an operational period of 240 days. Stable and high NOx− removal efficiency (NRE) of 96.6 ± 1.9% was determined under a stepwise decrease in HRT (from 9 h to 2 h), resulting in low total nitrogen concentrations of 24.0 ± 3.9 mg-N/L in the effluent. The circumneutral pH, associated with efficient elemental sulfur supply, facilitated to maintain the high NRE of S0dAD, which contributed to over 86.3% of the total NOx− removal in packed-bed reactor. Biomass in S0dAD packed-bed reactor was highly enriched with sulfur-oxidizing bacteria (SOB) (58.4%), including a predominant genus of Thiobacillus (47.7%) and two less-abundant genera of Sulfurimonas (4.5%) and Sulfurovum (5.5%). This study highlights the potential implementation of S0dAD coupled with PN/A process for advanced nitrogen removal from carbon-deficient ammonium-laden wastewater, particularly mature landfill leachate.

Biochemical oxidation and reduction are the principle of biological water and wastewater treatment, in which electron donor and/or acceptor shall be provided. Elemental sulfur (S0) as a non-toxic and easily available material with low price, possesses both reductive and oxidative characteristics, suggesting that it is a suitable material for water and wastewater treatment. Recent advanced understanding of S0-respiring microorganisms and their metabolism further stimulated the development of S0-based technologies. As such, S0-based biotechnologies have emerged as cost-effective and attractive alternatives to conventional biological methods for water and wastewater treatment. For instance, S0-driven autotrophic denitrification substantially lower the operational cost for nitrogen removal from water and wastewater, compared to the conventional process with exogenous carbon source supplementation. The introduction of S0 can also avoid secondary pollution commonly caused by overdose of organic carbon. S0 reduction processes cost-effectively mineralize organic matter with low sludge production. Biological sulfide production using S0 as electron acceptor is also an attractive technology for metal-laden wastewater treatment, e.g. acid mine drainage. This paper outlines an overview of the fundamentals, characteristics and advances of the S0-based biotechnologies and highlights the functional S0-related microorganisms. In particular, the mechanisms of microorganisms accessing insoluble S0 and feasibility to improve S0 bio-utilization efficiency are critically discussed. Additionally, the research knowledge gaps, current process limitations, and required further developments are identified and discussed. © 2021 Elsevier Ltd

Shallow-water hydrothermal vents are widespread, especially in the Mediterranean Sea, owing to the active volcanism of the area. Apart free microbial communities’ investigations, few biological studies have been leaded yet. Investigations of microbial communities associated with Nematoda, an ecologically important group in sediments, can help to improve our overall understanding of these ecosystems. We used a multidisciplinary-approach, based on microscopic observations (scanning electron microscopy: SEM and Fluorescence In Situ Hybridization: FISH) coupled with a molecular diversity analysis using metabarcoding, based on the 16S rRNA gene (V3-V4 region), to characterize the bacterial community of a free-living marine nematode and its environment, the shallow hydrothermal vent near Naples (Italy). Observations of living bacteria in the intestine (FISH), molecular and phylogenetic analyses showed that this species of nematode harbors its own bacterial community, distinct from the surrounding sediment and water. Metabarcoding results revealed the specific microbiomes of the sediment from three sites of this hydrothermal area to be composed mainly of sulfur oxidizing and reducing related bacteria.

Shallow-water hydrothermal vents are widespread, especially in the Mediterranean Sea, owing to the active volcanism of the area. Apart free microbial communities’ investigations, few biological studies have been leaded yet. Investigations of microbial communities associated with Nematoda, an ecologically important group in sediments, can help to improve our overall understanding of these ecosystems. We used a multidisciplinary-approach, based on microscopic observations (scanning electron microscopy: SEM and Fluorescence In Situ Hybridization: FISH) coupled with a molecular diversity analysis using metabarcoding, based on the 16S rRNA gene (V3-V4 region), to characterize the bacterial community of a free-living marine nematode and its environment, the shallow hydrothermal vent near Naples (Italy). Observations of living bacteria in the intestine (FISH), molecular and phylogenetic analyses showed that this species of nematode harbors its own bacterial community, distinct from the surrounding sediment and water. Metabarcoding results revealed the specific microbiomes of the sediment from three sites of this hydrothermal area to be composed mainly of sulfur oxidizing and reducing related bacteria.

Removal of organic and inorganic sulfur compounds from sour gases is required because of their toxicity and atmospheric pollution. The most common are hydrogen sulfide (H2S) and methanethiol (MT). Under oxygen-limiting conditions about 92 mol% of sulfide is oxidized to sulfur by haloalkaliphilic sulfur-oxidizing bacteria (SOB), whilst the remainder is oxidized either biologically to sulfate or chemically to thiosulfate. MT is spontaneously oxidized to dimethyl disulfide (DMDS), which was found to inhibit the oxidation of sulfide to sulfate. Hence, we assessed the effect of DMDS on product formation in a lab-scale biodesulfurization setup. DMDS was quantified using a newly, in-house developed analytical method. Subsequently, a chemical reaction mechanism was proposed for the formation of methanethiol and dimethyl trisulfide from the reaction between sulfide and DMDS. Addition of DMDS resulted in significant inhibition of sulfate formation, leading to 96 mol% of sulfur formation. In addition, a reduction in the dominating haloalkaliphilic SOB species, Thioalkalivibrio sulfidiphilus, was observed in favor of Thioalkaibacter halophilus as a more DMDS-tolerant with the 50 % inhibition coefficient at 2.37 mM DMDS., BT/Environmental Biotechnology

A chemolithoautotrophic sulfur-oxidizing bacterium, strain SGTM(T) was isolated from snow collected in Japan. As electron donors for growth, SGTM(T) oxidized thiosulfate, tetrathionate and elemental sulfur. Heterotrophic growth was not observed. Growth of the novel isolate was observed at a temperature range of 5-28 degrees C, with optimum growth at 18 degrees C. SGTM(T) grew at a pH range of 4.3-7.4, with optimum growth at pH 6.1-7.1. Major components in the cellular fatty acid profile were summed feature 3 (C-16:1 omega 7c and/or C-16:1 omega 6c) and C-16:0. The complete genome of SGTM(T) consisted of a circular chromosome of approximately 3.4 Mbp and two plasmids. Phylogenetic analysis based on the 16S rRNA gene indicated that SGTM(T) represented a member of the genus Sulfuriferula, and its closest relative is Sulfuriferula thiophila mst6(T) with a sequence identity of 98%. A comparative genome analysis showed dissimilarity between the genomes of SGTM(T) and S. thiophila mst6(T), as low values of average nucleotide identity (74.9%) and digital DNA-DNA hybridization (20.4%). On the basis of its genomic and phenotypic properties. SGTM(T) (=DSM 109609(T)=BCRC 81185(T)) is proposed as the type strain of a novel species, Sulfuriferula nivalis sp. nov. Some characteristics of another species in the same genus, Sulfuriferula plumbiphila, were also investigated to revise and supplement its description. The type strain of S. plumbiphila can grow on thiosulfate, tetrathionate and elemental sulfur. The strain showed optimum growth at pH 6.3-7.0 and shared major cellular fatty acids with the other species of the genus Sulfuriferula.

Aerobic, Gram-stain-negative, obligately chemolithoautotrophic thiosulfate-oxidizing bacteria, strains AkT22(T)and aks77(T)were isolated from a brackish lake in Japan. Strains AkT22(T)and aks77(T)were isolated from samples of eelgrass and sediment, respectively. Growth on sulfide, tetrathionate, elemental sulfur, and organic substrates was not observed for both strains. Growth of the strains was observed at 5 degrees C or higher temperature, with optimum growth at 22 degrees C. Strain AkT22(T)grew at a pH range of 5.8-8.0, with optimum growth at pH 6.7-7.8. Strain aks77(T)grew at a pH range of 5.8-8.5, with optimum growth at pH 7.0-7.9. Major cellular fatty acids (> 10% of total) of strain AkT22(T)were C-16:1, C-18:1, and C-16:0. The sole respiratory quinone was ubiquinone-8 in both strains. The genome of strain AkT22(T)consisted of a circular chromosome, with size of approximately 2.6 Mbp and G + C content of 43.2%. Those values of the genome of strain aks77(T)were ca. 2.7 Mbp and 45.5%, respectively. Among cultured bacteria,Thiomicrorhabdus aquaedulcisHaS4(T)showed the highest sequence identities of the 16S rRNA gene, to strains AkT22(T)(94%) and aks77(T)(95%). On the basis of these results,Thiosulfativibrio zosteraegen. nov., sp. nov. andThiosulfatimonas sediminisgen. nov., sp. nov. are proposed, with type strains of AkT22(T)(= BCRC 81184(T) = NBRC 114012(T) = DSM 109948(T)) and aks77(T)(= BCRC 81183(T) = NBRC 114013(T)), respectively.

Shallow-water hydrothermal vents are widespread, especially in the Mediterranean Sea, owing to the active volcanism of the area. Apart free microbial communities’ investigations, few biological studies have been leaded yet. Investigations of microbial communities associated with Nematoda, an ecologically important group in sediments, can help to improve our overall understanding of these ecosystems. We used a multidisciplinary-approach, based on microscopic observations (scanning electron microscopy: SEM and Fluorescence In Situ Hybridization: FISH) coupled with a molecular diversity analysis using metabarcoding, based on the 16S rRNA gene (V3-V4 region), to characterize the bacterial community of a free-living marine nematode and its environment, the shallow hydrothermal vent near Naples (Italy). Observations of living bacteria in the intestine (FISH), molecular and phylogenetic analyses showed that this species of nematode harbors its own bacterial community, distinct from the surrounding sediment and water. Metabarcoding results revealed the specific microbiomes of the sediment from three sites of this hydrothermal area to be composed mainly of sulfur oxidizing and reducing related bacteria.

A chemolithoautotrophic sulfur-oxidizing bacterium, strain SGTM(T) was isolated from snow collected in Japan. As electron donors for growth, SGTM(T) oxidized thiosulfate, tetrathionate and elemental sulfur. Heterotrophic growth was not observed. Growth of the novel isolate was observed at a temperature range of 5-28 degrees C, with optimum growth at 18 degrees C. SGTM(T) grew at a pH range of 4.3-7.4, with optimum growth at pH 6.1-7.1. Major components in the cellular fatty acid profile were summed feature 3 (C-16:1 omega 7c and/or C-16:1 omega 6c) and C-16:0. The complete genome of SGTM(T) consisted of a circular chromosome of approximately 3.4 Mbp and two plasmids. Phylogenetic analysis based on the 16S rRNA gene indicated that SGTM(T) represented a member of the genus Sulfuriferula, and its closest relative is Sulfuriferula thiophila mst6(T) with a sequence identity of 98%. A comparative genome analysis showed dissimilarity between the genomes of SGTM(T) and S. thiophila mst6(T), as low values of average nucleotide identity (74.9%) and digital DNA-DNA hybridization (20.4%). On the basis of its genomic and phenotypic properties. SGTM(T) (=DSM 109609(T)=BCRC 81185(T)) is proposed as the type strain of a novel species, Sulfuriferula nivalis sp. nov. Some characteristics of another species in the same genus, Sulfuriferula plumbiphila, were also investigated to revise and supplement its description. The type strain of S. plumbiphila can grow on thiosulfate, tetrathionate and elemental sulfur. The strain showed optimum growth at pH 6.3-7.0 and shared major cellular fatty acids with the other species of the genus Sulfuriferula.

A chemolithoautotrophic sulfur-oxidizing bacterium, strain SGTM(T) was isolated from snow collected in Japan. As electron donors for growth, SGTM(T) oxidized thiosulfate, tetrathionate and elemental sulfur. Heterotrophic growth was not observed. Growth of the novel isolate was observed at a temperature range of 5-28 degrees C, with optimum growth at 18 degrees C. SGTM(T) grew at a pH range of 4.3-7.4, with optimum growth at pH 6.1-7.1. Major components in the cellular fatty acid profile were summed feature 3 (C-16:1 omega 7c and/or C-16:1 omega 6c) and C-16:0. The complete genome of SGTM(T) consisted of a circular chromosome of approximately 3.4 Mbp and two plasmids. Phylogenetic analysis based on the 16S rRNA gene indicated that SGTM(T) represented a member of the genus Sulfuriferula, and its closest relative is Sulfuriferula thiophila mst6(T) with a sequence identity of 98%. A comparative genome analysis showed dissimilarity between the genomes of SGTM(T) and S. thiophila mst6(T), as low values of average nucleotide identity (74.9%) and digital DNA-DNA hybridization (20.4%). On the basis of its genomic and phenotypic properties. SGTM(T) (=DSM 109609(T)=BCRC 81185(T)) is proposed as the type strain of a novel species, Sulfuriferula nivalis sp. nov. Some characteristics of another species in the same genus, Sulfuriferula plumbiphila, were also investigated to revise and supplement its description. The type strain of S. plumbiphila can grow on thiosulfate, tetrathionate and elemental sulfur. The strain showed optimum growth at pH 6.3-7.0 and shared major cellular fatty acids with the other species of the genus Sulfuriferula.

Shallow-water hydrothermal vents are widespread, especially in the Mediterranean Sea, owing to the active volcanism of the area. Apart free microbial communities’ investigations, few biological studies have been leaded yet. Investigations of microbial communities associated with Nematoda, an ecologically important group in sediments, can help to improve our overall understanding of these ecosystems. We used a multidisciplinary-approach, based on microscopic observations (scanning electron microscopy: SEM and Fluorescence In Situ Hybridization: FISH) coupled with a molecular diversity analysis using metabarcoding, based on the 16S rRNA gene (V3-V4 region), to characterize the bacterial community of a free-living marine nematode and its environment, the shallow hydrothermal vent near Naples (Italy). Observations of living bacteria in the intestine (FISH), molecular and phylogenetic analyses showed that this species of nematode harbors its own bacterial community, distinct from the surrounding sediment and water. Metabarcoding results revealed the specific microbiomes of the sediment from three sites of this hydrothermal area to be composed mainly of sulfur oxidizing and reducing related bacteria.

Aerobic, Gram-stain-negative, obligately chemolithoautotrophic thiosulfate-oxidizing bacteria, strains AkT22(T)and aks77(T)were isolated from a brackish lake in Japan. Strains AkT22(T)and aks77(T)were isolated from samples of eelgrass and sediment, respectively. Growth on sulfide, tetrathionate, elemental sulfur, and organic substrates was not observed for both strains. Growth of the strains was observed at 5 degrees C or higher temperature, with optimum growth at 22 degrees C. Strain AkT22(T)grew at a pH range of 5.8-8.0, with optimum growth at pH 6.7-7.8. Strain aks77(T)grew at a pH range of 5.8-8.5, with optimum growth at pH 7.0-7.9. Major cellular fatty acids (> 10% of total) of strain AkT22(T)were C-16:1, C-18:1, and C-16:0. The sole respiratory quinone was ubiquinone-8 in both strains. The genome of strain AkT22(T)consisted of a circular chromosome, with size of approximately 2.6 Mbp and G + C content of 43.2%. Those values of the genome of strain aks77(T)were ca. 2.7 Mbp and 45.5%, respectively. Among cultured bacteria,Thiomicrorhabdus aquaedulcisHaS4(T)showed the highest sequence identities of the 16S rRNA gene, to strains AkT22(T)(94%) and aks77(T)(95%). On the basis of these results,Thiosulfativibrio zosteraegen. nov., sp. nov. andThiosulfatimonas sediminisgen. nov., sp. nov. are proposed, with type strains of AkT22(T)(= BCRC 81184(T) = NBRC 114012(T) = DSM 109948(T)) and aks77(T)(= BCRC 81183(T) = NBRC 114013(T)), respectively.

Removal of organic and inorganic sulfur compounds from sour gases is required because of their toxicity and atmospheric pollution. The most common are hydrogen sulfide (H2S) and methanethiol (MT). Under oxygen-limiting conditions about 92 mol% of sulfide is oxidized to sulfur by haloalkaliphilic sulfur-oxidizing bacteria (SOB), whilst the remainder is oxidized either biologically to sulfate or chemically to thiosulfate. MT is spontaneously oxidized to dimethyl disulfide (DMDS), which was found to inhibit the oxidation of sulfide to sulfate. Hence, we assessed the effect of DMDS on product formation in a lab-scale biodesulfurization setup. DMDS was quantified using a newly, in-house developed analytical method. Subsequently, a chemical reaction mechanism was proposed for the formation of methanethiol and dimethyl trisulfide from the reaction between sulfide and DMDS. Addition of DMDS resulted in significant inhibition of sulfate formation, leading to 96 mol% of sulfur formation. In addition, a reduction in the dominating haloalkaliphilic SOB species, Thioalkalivibrio sulfidiphilus, was observed in favor of Thioalkaibacter halophilus as a more DMDS-tolerant with the 50 % inhibition coefficient at 2.37 mM DMDS., BT/Environmental Biotechnology

Removal of organic and inorganic sulfur compounds from sour gases is required because of their toxicity and atmospheric pollution. The most common are hydrogen sulfide (H2S) and methanethiol (MT). Under oxygen-limiting conditions about 92 mol% of sulfide is oxidized to sulfur by haloalkaliphilic sulfur-oxidizing bacteria (SOB), whilst the remainder is oxidized either biologically to sulfate or chemically to thiosulfate. MT is spontaneously oxidized to dimethyl disulfide (DMDS), which was found to inhibit the oxidation of sulfide to sulfate. Hence, we assessed the effect of DMDS on product formation in a lab-scale biodesulfurization setup. DMDS was quantified using a newly, in-house developed analytical method. Subsequently, a chemical reaction mechanism was proposed for the formation of methanethiol and dimethyl trisulfide from the reaction between sulfide and DMDS. Addition of DMDS resulted in significant inhibition of sulfate formation, leading to 96 mol% of sulfur formation. In addition, a reduction in the dominating haloalkaliphilic SOB species, Thioalkalivibrio sulfidiphilus, was observed in favor of Thioalkaibacter halophilus as a more DMDS-tolerant with the 50 % inhibition coefficient at 2.37 mM DMDS.

The genus Thioalkalivibrio includes haloalkaliphilic chemolithoautotrophic sulfur-oxidizing bacteria isolated from various soda lakes worldwide. Some of these lakes possess in addition to their extreme haloalkaline environment also other harsh conditions, to which Thioalkalivibrio needs to adapt. An example is arsenic in soda lakes in eastern California, which is found there in concentrations up to 3000 μM. Arsenic is a widespread element that can be an environmental issue, as it is highly toxic to most organisms. However, resistance mechanisms in the form of detoxification are widespread and some prokaryotes can even use arsenic as an energy source. We first screened the genomes of 76 Thioalkalivibrio strains for the presence of known arsenic oxidoreductases and found 15 putative ArxA (arsenite oxidase) and two putative ArrA (arsenate reductase). Subsequently, we studied the resistance to arsenite in detail in Thioalkalivibrio jannaschii ALM2T, and Thioalkalivibrio thiocyanoxidans ARh2T by comparative genomics and by growing them at different arsenite concentrations followed by arsenic species and transcriptomic analysis. Tv. jannaschii ALM2T, which has been isolated from Mono Lake, an arsenic-rich soda lake, could resist up to 5 mM arsenite, whereas Tv. thiocyanoxidans ARh2T, which was isolated from a Kenyan soda lake, could only grow up to 0.1 mM arsenite. Interestingly, both species oxidized arsenite to arsenate under aerobic conditions, although Tv. thiocyanoxidans ARh2T does not contain any known arsenite oxidases, and in Tv. jannaschii ALM2T, only arxB2 was clearly upregulated. However, we found the expression of a SoeABC-like gene, which we assume might have been involved in arsenite oxidation. Other arsenite stress responses for both strains were the upregulation of the vitamin B12 synthesis pathway, which can be linked to antioxidant activity, and the up- and downregulation of different DsrE/F-like genes whose roles are still unclear. Moreover, Tv. jann, BT/Environmental Biotechnology

Hydrogen sulfide is a toxic and corrosive gas that must be removed from gaseous hydrocarbon streams prior to combustion. This paper describes a gas biodesulfurization process where sulfur-oxidizing bacteria (SOB) facilitate sulfide conversion to both sulfur and sulfate. In order to optimize the formation of sulfur, it is crucial to understand the relations between the SOB microbial composition, kinetics of biological and abiotic sulfide oxidation and the effects on the biodesulfurization process efficiency. Hence, a physiologically based kinetic model was developed for four different inocula. The resulting model can be used as a tool to evaluate biodesulfurization process performance. The model relies on a ratio of two key enzymes involved in the sulfide oxidation process, i.e., flavocytochrome c and sulfide-quinone oxidoreductase (FCC and SQR). The model was calibrated by measuring biological sulfide oxidation rates for different inocula obtained from four full-scale biodesulfurization installations fed with gases from various industries. Experimentally obtained biological sulfide oxidation rates showed dissimilarities between the tested biomasses which could be explained by assuming distinctions in the key-enzyme ratios. Hence, we introduce a new model parameter α to whereby α describes the ratio between the relative expression levels of FCC and SQR enzymes. Our experiments show that sulfur production is the highest at low α values.

Strain HaS4(T) is an aerobic sulfur-oxidizing bacterium isolated from water of Lake Harutori in Japan. It was isolated and partially characterized in a previous study, but its taxonomic status has not been determined. The previous study revealed that the strain is an obligate chemolithoautotroph which grows at temperatures ranging from 0 to 25 degrees C (optimum, 22 degrees C) and pH from pH 6.2 to 8.8 (optimum, pH 6.6-7.4). In this study, further characterization of the strain was made to describe it as representative of a novel species. Cells of strain HaS4(T) are rod-shaped, 1.6-2.5 mu m long, 0.7-0.9 mu m wide and Gram-stain-negative. Major cellular fatty acids were summed feature 3 (C-16 : 1 omega 7c and/or C-16 : 1 omega 6c), summed feature 8 (C-18 : 1 omega 7c and/or C-18 : 1 omega 6c) and C-16 : 0. Phylogenetic analysis based on the 16S rRNA gene indicated that the strain is related to the genus Thiomicrorhabdus, but phylogenetically distinct from the type strains of existing species in the genus. On the basis of its phylogenetic and phenotypic properties, strain HaS4(T) (=NBRC 112315(T)=BCRC 81110(T)) is proposed as type strain of a new non-marine species of the genus Thiomicrorhabdus with the name Thiomicrorhabdus aquaedulcis sp. nov.

Strain HaS4(T) is an aerobic sulfur-oxidizing bacterium isolated from water of Lake Harutori in Japan. It was isolated and partially characterized in a previous study, but its taxonomic status has not been determined. The previous study revealed that the strain is an obligate chemolithoautotroph which grows at temperatures ranging from 0 to 25 degrees C (optimum, 22 degrees C) and pH from pH 6.2 to 8.8 (optimum, pH 6.6-7.4). In this study, further characterization of the strain was made to describe it as representative of a novel species. Cells of strain HaS4(T) are rod-shaped, 1.6-2.5 mu m long, 0.7-0.9 mu m wide and Gram-stain-negative. Major cellular fatty acids were summed feature 3 (C-16 : 1 omega 7c and/or C-16 : 1 omega 6c), summed feature 8 (C-18 : 1 omega 7c and/or C-18 : 1 omega 6c) and C-16 : 0. Phylogenetic analysis based on the 16S rRNA gene indicated that the strain is related to the genus Thiomicrorhabdus, but phylogenetically distinct from the type strains of existing species in the genus. On the basis of its phylogenetic and phenotypic properties, strain HaS4(T) (=NBRC 112315(T)=BCRC 81110(T)) is proposed as type strain of a new non-marine species of the genus Thiomicrorhabdus with the name Thiomicrorhabdus aquaedulcis sp. nov.

Strain HaS4(T) is an aerobic sulfur-oxidizing bacterium isolated from water of Lake Harutori in Japan. It was isolated and partially characterized in a previous study, but its taxonomic status has not been determined. The previous study revealed that the strain is an obligate chemolithoautotroph which grows at temperatures ranging from 0 to 25 degrees C (optimum, 22 degrees C) and pH from pH 6.2 to 8.8 (optimum, pH 6.6-7.4). In this study, further characterization of the strain was made to describe it as representative of a novel species. Cells of strain HaS4(T) are rod-shaped, 1.6-2.5 mu m long, 0.7-0.9 mu m wide and Gram-stain-negative. Major cellular fatty acids were summed feature 3 (C-16 : 1 omega 7c and/or C-16 : 1 omega 6c), summed feature 8 (C-18 : 1 omega 7c and/or C-18 : 1 omega 6c) and C-16 : 0. Phylogenetic analysis based on the 16S rRNA gene indicated that the strain is related to the genus Thiomicrorhabdus, but phylogenetically distinct from the type strains of existing species in the genus. On the basis of its phylogenetic and phenotypic properties, strain HaS4(T) (=NBRC 112315(T)=BCRC 81110(T)) is proposed as type strain of a new non-marine species of the genus Thiomicrorhabdus with the name Thiomicrorhabdus aquaedulcis sp. nov.

Here we report the chemical and microbial characterization of the surface water of a CO2-rich hydrothermal vent known in Costa Rica as Borbollones, located at Tenorio Volcano National Park. The Borbollones showed a temperature surrounding 60 °C, a pH of 2.4 and the gas released has a composition of ~ 97% CO2, ~ 0.07% H2S, ~ 2.3% N2 and ~ 0.12% CH4. Other chemical species such as sulfate and iron were found at high levels with respect to typical fresh water bodies. Analysis by 16S rRNA gene metabarcoding revealed that in Borbollones predominates an archaeon from the order Thermoplasmatales and one bacterium from the genus Sulfurimonas. Other sulfur- (genera Thiomonas, Acidithiobacillus, Sulfuriferula, and Sulfuricurvum) and iron-oxidizing bacteria (genera Sideroxydans, Gallionella, and Ferrovum) were identified. Our results show that CO2-influenced surface water of Borbollones contains microorganisms that are usually found in acid rock drainage environments or sulfur-rich hydrothermal vents. To our knowledge, this is the first microbiological characterization of a CO2-dominated hydrothermal spring from Central America and expands our understanding of those extreme ecosystems.

Chemolithoautotrophic sulfur-oxidizing bacteria (SOB) are crucial key players in biotechnological processes to remove hydrogen sulfide from sour gas streams. Several different haloalkaliphilic SOB have been detected and isolated from lab- and full-scale facilities, which all performed differently considering end product yields (sulfur and sulfate) and conversion rates. Understanding and regulating bacterial community dynamics in biodesulfurization processes will enable optimization of the process operation. We developed quantitative PCR (qPCR) assays to quantify haloalkaliphilic sulfur-oxidizing gammaproteobacterial species Alkalilimnicola ehrlichii, Thioalkalivibrio sulfidiphilus, and Thioalkalibacter halophilus that dominate bacterial communities of biodesulfurization lab- and full-scale installations at haloalkaline conditions. The specificity and PCR efficiency of novel primer sets were evaluated using pure cultures of these target species. We further validated the qPCR assays by quantification of target organisms in five globally distributed full-scale biodesulfurization installations. The qPCR assays perform a sensitive and accurate quantification of Alkalilimnicola ehrlichii, Thioalkalivibrio sulfidiphilus and Thioalkalibacter halophilus, thus providing rapid and valuable insights into process performance and SOB growth dynamics in gas biodesulfurization systems.

Deep-sea hydrothermal vent meiofauna have been the focus of recent research and the discovery of an abundant well-adapted free-living marine nematode on the Mid-Atlantic Ridge offers new perspectives on adaptations to the vent environment. Indeed, knowledge concerning biological interactions of microbes and meiofauna in marine extreme environments is scarce, especially for nematodes. In this study, we used microscopic observations [fluorescence in situ hybridization (FISH) and scanning electron microscopy (SEM)] and metabarcoding of 16S rRNA to characterize the bacterial community of the nematode species Oncholaimus dyvae, an overlooked but ecologically important vent organism. Detection of bacteria in the buccal cavity and on the cuticle (SEM) and epibionts in its intestine (FISH) suggests that O. dyvae harbors its own bacterial community. Molecular results and phylogenetic analysis show that bacteria associated with this species are related to symbiotic lineages typical of hydrothermal vent fauna, such as sulfur-oxidizing bacteria related to Epsilonproteobacteria and Gammaproteobacteria. This multi-approach study suggests a potential symbiotic role of bacteria with its nematode host and opens new research perspectives on vent meiofauna.

Deep-sea hydrothermal vent meiofauna have been the focus of recent research and the discovery of an abundant well-adapted free-living marine nematode on the Mid-Atlantic Ridge offers new perspectives on adaptations to the vent environment. Indeed, knowledge concerning biological interactions of microbes and meiofauna in marine extreme environments is scarce, especially for nematodes. In this study, we used microscopic observations [fluorescence in situ hybridization (FISH) and scanning electron microscopy (SEM)] and metabarcoding of 16S rRNA to characterize the bacterial community of the nematode species Oncholaimus dyvae, an overlooked but ecologically important vent organism. Detection of bacteria in the buccal cavity and on the cuticle (SEM) and epibionts in its intestine (FISH) suggests that O. dyvae harbors its own bacterial community. Molecular results and phylogenetic analysis show that bacteria associated with this species are related to symbiotic lineages typical of hydrothermal vent fauna, such as sulfur-oxidizing bacteria related to Epsilonproteobacteria and Gammaproteobacteria. This multi-approach study suggests a potential symbiotic role of bacteria with its nematode host and opens new research perspectives on vent meiofauna.

Deep-sea hydrothermal vent meiofauna have been the focus of recent research and the discovery of an abundant well-adapted free-living marine nematode on the Mid-Atlantic Ridge offers new perspectives on adaptations to the vent environment. Indeed, knowledge concerning biological interactions of microbes and meiofauna in marine extreme environments is scarce, especially for nematodes. In this study, we used microscopic observations [fluorescence in situ hybridization (FISH) and scanning electron microscopy (SEM)] and metabarcoding of 16S rRNA to characterize the bacterial community of the nematode species Oncholaimus dyvae, an overlooked but ecologically important vent organism. Detection of bacteria in the buccal cavity and on the cuticle (SEM) and epibionts in its intestine (FISH) suggests that O. dyvae harbors its own bacterial community. Molecular results and phylogenetic analysis show that bacteria associated with this species are related to symbiotic lineages typical of hydrothermal vent fauna, such as sulfur-oxidizing bacteria related to Epsilonproteobacteria and Gammaproteobacteria. This multi-approach study suggests a potential symbiotic role of bacteria with its nematode host and opens new research perspectives on vent meiofauna.

A novel Gram-stain-negative, chemolithoautotrophic sulfur oxidizer, strain JG42(T), was isolated from a hot spring microbial mat. As an electron donor for autotrophic growth, strain JG42(T) utilized sulfide, thiosulfate, tetrathionate and elemental sulfur. Cells of strain JG42(T) were oxidase-positive and catalase-negative. The G+C content of the genomic DNA was 65 mol%. The predominant cellular fatty acid was C-16:0. Phylogenetic analysis of the 16S rRNA gene indicated that strain JG42(T) belonged to the order Chromatiales, but sequence similarities to the known species were less than 94 %. On the basis of its properties, strain JG42(T) (= DSM 104776(T) = NBRC 112696(T)) is proposed as the type strain of a novel species of a new genus, Sulfurivermis fontis gen. nov., sp. nov., which belongs to the family Thioalkalispiraceae. A new family, Thioprofundaceae fam. nov., is also proposed to accommodate the genus Thioprofundum, transferred from the family Thioalkalispiraceae.

A novel sulfur-oxidizing autotrophic bacterium, strain J1A(T) was isolated from a hot spring microbial mat. The cells were Gram-stain-negative, catalase-negative and oxidase-positive. As sole electron donor for chemolithoautotrophic growth, strain J1A(T) utilized sulfide, thiosulfate, elemental sulfur, and tetrathionate. The G+C content of the genomic DNA was 66 mol%. Major cellular fatty acids (>40% of total) were C-16:0 and summed feature 3 (C-16:1 omega 7c and/or C-16:1 omega 6c). The predominant quinone was Q-8. Phylogenetic analysis of the 16S rRNA gene indicated that strain J1A(T) is a relative of species of the genus Thiobacillus, but shares only 93% or lower sequence similarities with them. On the basis of its properties, strain J1A(T) represents a novel species of a new genus, for which the name Sulfuritortus calidifontis gen. nov., sp. nov. is proposed. The type strain of the type species is J1A(T) (=DSM 103923(T)=NBRC 112474(T)).

A novel sulfur-oxidizing autotrophic bacterium, strain J1A(T) was isolated from a hot spring microbial mat. The cells were Gram-stain-negative, catalase-negative and oxidase-positive. As sole electron donor for chemolithoautotrophic growth, strain J1A(T) utilized sulfide, thiosulfate, elemental sulfur, and tetrathionate. The G+C content of the genomic DNA was 66 mol%. Major cellular fatty acids (>40% of total) were C-16:0 and summed feature 3 (C-16:1 omega 7c and/or C-16:1 omega 6c). The predominant quinone was Q-8. Phylogenetic analysis of the 16S rRNA gene indicated that strain J1A(T) is a relative of species of the genus Thiobacillus, but shares only 93% or lower sequence similarities with them. On the basis of its properties, strain J1A(T) represents a novel species of a new genus, for which the name Sulfuritortus calidifontis gen. nov., sp. nov. is proposed. The type strain of the type species is J1A(T) (=DSM 103923(T)=NBRC 112474(T)).

A novel Gram-stain-negative, chemolithoautotrophic sulfur oxidizer, strain JG42(T), was isolated from a hot spring microbial mat. As an electron donor for autotrophic growth, strain JG42(T) utilized sulfide, thiosulfate, tetrathionate and elemental sulfur. Cells of strain JG42(T) were oxidase-positive and catalase-negative. The G+C content of the genomic DNA was 65 mol%. The predominant cellular fatty acid was C-16:0. Phylogenetic analysis of the 16S rRNA gene indicated that strain JG42(T) belonged to the order Chromatiales, but sequence similarities to the known species were less than 94 %. On the basis of its properties, strain JG42(T) (= DSM 104776(T) = NBRC 112696(T)) is proposed as the type strain of a novel species of a new genus, Sulfurivermis fontis gen. nov., sp. nov., which belongs to the family Thioalkalispiraceae. A new family, Thioprofundaceae fam. nov., is also proposed to accommodate the genus Thioprofundum, transferred from the family Thioalkalispiraceae.

A novel sulfur-oxidizing autotrophic bacterium, strain J1A(T) was isolated from a hot spring microbial mat. The cells were Gram-stain-negative, catalase-negative and oxidase-positive. As sole electron donor for chemolithoautotrophic growth, strain J1A(T) utilized sulfide, thiosulfate, elemental sulfur, and tetrathionate. The G+C content of the genomic DNA was 66 mol%. Major cellular fatty acids (>40% of total) were C-16:0 and summed feature 3 (C-16:1 omega 7c and/or C-16:1 omega 6c). The predominant quinone was Q-8. Phylogenetic analysis of the 16S rRNA gene indicated that strain J1A(T) is a relative of species of the genus Thiobacillus, but shares only 93% or lower sequence similarities with them. On the basis of its properties, strain J1A(T) represents a novel species of a new genus, for which the name Sulfuritortus calidifontis gen. nov., sp. nov. is proposed. The type strain of the type species is J1A(T) (=DSM 103923(T)=NBRC 112474(T)).

Sulfur-oxidizing bacteria (SOB) was successfully employed for effective autotrophic denitrification and sludge minimization in a full-scale application of saline sewage treatment in Hong Kong. In this study, a Granular Sludge Autotrophic Denitrification (GSAD) reactor was continuously operated over 600 days for SOB granulation, and to evaluate the long-term stability of SOB granules, microbial communities and denitrification efficacy. Sludge granulation initiated within the first 40 days of start-up with an average particle size of 186.4 μm and sludge volume index (SVI5) of 40 mL/g in 5 min. The sludge granules continued to grow reaching a nearly uniform size of mean diameter 1380 ± 20 μm with SVI5 of 30 mL/g during 600 days of GSAD reactor operation at hydraulic retention time of 5 h and nitrate loading rate of 0.33 kg-N/m3/d. The GSAD reactor with SOB granular sludge achieved 93.7 ± 2.1% nitrogen and complete sulfide removal with low sludge yield of 0.15 g-volatile suspended solids (VSS)/g-N, and much lower nitrous oxide (N2O) emission than the heterotrophic denitrifying process. Microbial community analysis using fluorescence in situ hybridization (FISH) technique revealed that granules were enriched with SOB contributing to autotrophic denitrification. Furthermore, 16S rRNA analysis showed diverse autotrophic denitrification related genera, namely Thiobacillus (32.6%), Sulfurimonas (31.3%), and Arcobacter (0.01%), accounting for 63.9% of total operational taxonomic units at the generic level. No heterotrophic denitrification related genera were detected. The results from this study could provide useful design and operating conditions with respect to SOB sludge granulation and its subsequent application in a full-scale autotrophic denitrification in the Sulfate reduction-Autotrophic denitrification-Nitrification Integrated (SANI) process. © 2016 Elsevier Ltd

Sulfurifustis variabilis and Sulfuricaulis limicola are autotrophic sulfur-oxidizing bacteria belonging to the family Acidiferrobacteraceae in the order Acidiferrobacterales. The type strains of these species, strain skN76(T) and strain HA5(T), were isolated from lakes in Japan. Here we describe the complete genome sequences of Sulfurifustis variabilis skN76T and Sulfuricaulis limicola HA5T. The genome of Sulfurifustis variabilis skN76T consists of one circular chromosome with size of 4.0 Mbp including 3864 protein-coding sequences. The genome of Sulfuricaulis limicola HA5T is 2.9 Mbp chromosome with 2763 protein-coding sequences. In both genomes, 46 transfer RNA-coding genes and one ribosomal RNA operon were identified. In the genomes, redundancies of the genes involved in sulfur oxidation and inorganic carbon fixation pathways were observed. This is the first report to show the complete genome sequences of bacteria belonging to the order Acidiferrobacterales in the class Gammaproteobacteria.

Sulfurifustis variabilis and Sulfuricaulis limicola are autotrophic sulfur-oxidizing bacteria belonging to the family Acidiferrobacteraceae in the order Acidiferrobacterales. The type strains of these species, strain skN76(T) and strain HA5(T), were isolated from lakes in Japan. Here we describe the complete genome sequences of Sulfurifustis variabilis skN76T and Sulfuricaulis limicola HA5T. The genome of Sulfurifustis variabilis skN76T consists of one circular chromosome with size of 4.0 Mbp including 3864 protein-coding sequences. The genome of Sulfuricaulis limicola HA5T is 2.9 Mbp chromosome with 2763 protein-coding sequences. In both genomes, 46 transfer RNA-coding genes and one ribosomal RNA operon were identified. In the genomes, redundancies of the genes involved in sulfur oxidation and inorganic carbon fixation pathways were observed. This is the first report to show the complete genome sequences of bacteria belonging to the order Acidiferrobacterales in the class Gammaproteobacteria.

Sulfurifustis variabilis and Sulfuricaulis limicola are autotrophic sulfur-oxidizing bacteria belonging to the family Acidiferrobacteraceae in the order Acidiferrobacterales. The type strains of these species, strain skN76(T) and strain HA5(T), were isolated from lakes in Japan. Here we describe the complete genome sequences of Sulfurifustis variabilis skN76T and Sulfuricaulis limicola HA5T. The genome of Sulfurifustis variabilis skN76T consists of one circular chromosome with size of 4.0 Mbp including 3864 protein-coding sequences. The genome of Sulfuricaulis limicola HA5T is 2.9 Mbp chromosome with 2763 protein-coding sequences. In both genomes, 46 transfer RNA-coding genes and one ribosomal RNA operon were identified. In the genomes, redundancies of the genes involved in sulfur oxidation and inorganic carbon fixation pathways were observed. This is the first report to show the complete genome sequences of bacteria belonging to the order Acidiferrobacterales in the class Gammaproteobacteria.