Summary auto-generated
Researchers isolated a novel alkaliphilic, sulfate-reducing bacterium designated Desulfonatronovibrio hydrogenovorans (strain Z-7935T) from sediments of Lake Magadi in Kenya. This gram-negative vibrio is strictly anaerobic and uniquely restricted to using only hydrogen and formate as electron donors while reducing sulfate, sulfite, and thiosulfate as electron acceptors. The organism is an obligate alkaliphile requiring sodium ions, with optimal growth at pH 9.5-9.7 and 37°C, and cannot grow at neutral pH or above pH 10.2. It requires vitamins, acetate, and other organic compounds for anabolic reactions, making it lithoheterotrophic. The DNA G+C content is 48.6 mol%. Phylogenetic analysis of 16S rRNA gene sequences revealed that strain Z-7935T represents a distinct lineage within the delta subclass of Proteobacteria, clustering with Desulfohalobium retbaense with 88.7% sequence similarity. The organism's narrow substrate utilization, unique fatty acid profile, and phylogenetic distinctiveness supported proposal of a new genus and species. This discovery is ecologically significant as it represents the first successful isolation of an alkaliphilic sulfate-reducer from a soda lake environment, contributing to understanding of bacterial hydrogen consumption and alkalinity development in extreme alkaline ecosystems.
Key findings
- Desulfonatronovibrio hydrogenovorans is a newly described alkaliphilic sulfate-reducing bacterium with restricted metabolism, utilizing only hydrogen and formate as electron donors and sulfate, sulfite, and thiosulfate as electron acceptors.
- The organism is an obligate alkaliphile requiring sodium ions, with optimal growth at pH 9.5-9.7 and inability to grow at neutral pH, explaining its ecological niche in soda lakes.
- Phylogenetic analysis of 16S rRNA sequences indicates strain Z-7935T represents a novel genus-level lineage within delta Proteobacteria, representing an important discovery for understanding sulfate reduction in extreme alkaline environments.
- The organism's lithoheterotrophic metabolism and consumption of hydrogen produced by primary anaerobes suggests its role as a key hydrogen sink in alkaline lake communities.
- The narrow range of substrates utilized (only H₂ and formate) is unusual among sulfate-reducing bacteria and represents a distinct physiological specialization for alkaline environments.
This summary was generated automatically from the article PDF and is not part of the original publication. Refer to the PDF for the authoritative text.
Abstract
A new alkaliphilic, sulfate-reducing bacterium, strain Z-7935T (T = type strain), was isolated from a soda-depositing lake, Lake Magadi in Kenya. This organism is a motile vibrio which utilizes only hydrogen and formate as electron donors and sulfate, sulfite, and thiosulfate, but not sulfur, as electron acceptors. Thiosulfate is dismutated. Strain Z-7935T is an obligately sodium-dependent alkaliphile which grows in sodium carbonate medium and does not grow at pH 7; the maximum pH for growth is more than pH 10, and the optimum pH is 9.5 to 9.7. The optimum NaCl concentration for growth is 3% (wt/vol). The optimum temperature for growth is 37°C. The G+C content of the DNA is 48.6 mol%. 16S ribosomal DNA sequence analysis revealed that strain Z-7935T represents a new lineage with genus status in the delta subclass of the Proteobac-teria. The name Desulfonatronovibrio hydrogenovorans gen. nov., sp. nov. is proposed for this organism; the type strain of D. hydrogenovorans is strain Z-7935 (= DSM 9292).