Deltaproteobacterium Strain KaireiS1, a Mesophilic, Hydrogen-Oxidizing and Sulfate-Reducing Bacterium From an Inactive Deep-Sea Hydrothermal Chimney

Abstract

A novel deltaproteobacterial, mesophilic, hydrogen-oxidizing, and sulfate-reducing bacterium (strain KaireiS1) was highly enriched from an inactive chimney located in the active zone of the Kairei hydrothermal vent field (Central Indian Ridge) in the Indian Ocean. Based on 16S rRNA gene analyses, strain KaireiS1 is the currently only cultured representative of a cluster of uncultured Deltaproteobacteria, positioned within the Desulfobulbaceae family, between the Desulfobulbus genus and the “Cable Bacteria.” A facultative autotrophic lifestyle of KaireiS1 is indicated by its growth in the absence of organic compounds, measurements of CO2-fixation rates, and activity measurements of carbon monoxide dehydrogenase, the key enzyme of the reductive Acetyl-CoA pathway. Apart from hydrogen, strain KaireiS1 can also use propionate, lactate, and pentadecane as electron donors. However, the highest cell numbers were reached when grown autotrophically with molecular hydrogen. Hydrogen uptake activity was found in membrane and soluble fractions of cell-free extracts and reached up to 2,981±129 nmol H2*min−1*mg−1 of partially purified protein. Commonly, autotrophic sulfate-reducing bacteria from the Deltaproteobacteria class, thriving in hydrothermal vent habitats are described as thermophiles. Given its physiological characteristics and specific isolation source, strain KaireiS1 demonstrates a previously unnoticed potential for microbial sulfate reduction by autotrophs taking place at moderate temperatures in hydrothermal vent fields.

Microbial H2 Consumption by a Formation Fluid from a Natural Gas Field at High-Pressure Conditions Relevant for Underground H2 Storage

“…Considering daily per cell H 2 consumption rates, the rates of 9−34 fmol of H 2 /(day cell) determined at AP were slower than oxidation rates of 245 fmol of H 2 /(day cell) observed recently by a marine H 2 -oxidizing SRP enriched from a hydrothermal deep sea vent. 48 Both were much slower than potential H 2 oxidation rates estimated for the sulfate-rich zone of marine and lacustrine sediment samples with 0.5−4 pmol of H 2 /(day cell). 49 However, these comparisons might be biased since the present study referred H 2 consumption to the sum of active and inactive cells as well as by comparing processes from different environments.…”

Physiological and comparative proteomic characterization of Desulfolithobacter dissulfuricans gen. nov., sp. nov., a novel mesophilic, sulfur-disproportionating chemolithoautotroph from a deep-sea hydrothermal vent

“…The closest cultured species were Desulfogranum mediterraneum 86FS1 T (93.3%; Sass et al, 2002 ) and Desulfobulbus sp. strain KaireiS1 (92.9%; Adam et al, 2021 ). These similarity values are below the common index of 16S rRNA gene sequence similarity for differentiation of microorganisms at the genus level (94.5%; Yarza et al, 2014 ; Figure 2A ).…”

Unique deep-sea bacterial assemblages thriving on different natural organic matters delivered via in situ incubators

“…S4). Most of these bacterial members were anaerobes or facultative anaerobes, like Marini laceae [33], Spirochaetaceae [34], Psychromonadaceae [35], Fusobacteriaceae [36], sulphur-oxidizing bacteria (SOBs) of Arcobacteraceae and Sulfurovaceae [37][38][39], sulphur-reducing bacteria of Sulfurospirillaceae [40], and sulphate-reducing bacteria (SRBs) of Desulfobulbaceae and Desulfobacteraceae [41,42]. In the in situ seawater collected by CICs, the putative anaerobic bacteria Woeseiaceae/JTB255 and SAR202 were recovered, which have been recognized as cosmopolitan and abundant core members of deep-sea surface sediments [43] and benthic water [44][45][46], respectively.…”

“…4); in contrast, the bacterial Sulfurovaceae is the predominant SOB in the hydrothermal plume close to a vent [62]. Evidently, they are not directly involved in macromolecular OM decomposition but oxidizing sulphides generated by SRBs, such as Desulfobulbaceae and Desulfobacteraceae, which might use the most common microbial fermentation products (e.g., acetate, propionate, butyrate, lactate, and hydrogen) as an energy source, coupled with sulphate, sulphite, and/or thiosulfate reduction, like cultured strain KaireiS1 and members of Desulfofrigus, Desulfofaba, and Desulfotalea [41,42]. Moreover, the chemoautotrophic lifestyle of Arcobacteraceae and Sulfurovaceae in the enrichments will suppress the accumulation of hydrogen sulphide; otherwise, sulphide may have detrimental effects on other microorganisms.…”