Thiomicrospira

Thiomicrospira is a genus of Gram-negative, chemoautotrophic bacteria that oxidize reduced sulfur compounds. Members are commonly found in marine environments where sulfide, thiosulfate, or elemental sulfur are available, including deep-sea hydrothermal vents, cold seeps, and coastal sediments. They can occur as free-living cells or associated with particulate matter or biofilms.

Metabolism and ecology: Thiomicrospira species obtain energy by oxidizing reduced sulfur compounds and use oxygen or nitrate as terminal electron acceptors. Through autotrophic carbon fixation, they convert inorganic carbon dioxide into biomass, supporting growth in environments where organic carbon is limited. As sulfur-oxidizing bacteria, they contribute to the marine sulfur cycle by converting reduced sulfur species to sulfate and influencing local biogeochemistry.

Morphology and physiology: Members are typically motile, Gram-negative bacteria with rod-shaped cells. They are generally adapted to saline, marine conditions and can tolerate a range of oxygen levels, from aerobic to microaerophilic environments. Temperature tolerance varies among species, with some inhabiting cooler surface waters and others associated with warmer, vent-related habitats.

Taxonomy and diversity: The genus Thiomicrospira comprises several species, including well-studied strains isolated from marine and vent-related environments. They are part of the broader group of sulfur-oxidizing Gammaproteobacteria, and molecular studies have helped clarify their phylogenetic relationships within marine chemolithoautotrophs.

Ecological significance: Thiomicrospira species play a role in primary production in sulfur-rich marine systems and contribute to sulfur speciation and nutrient cycling in both deep-sea and coastal ecosystems. Their study informs understanding of chemolithotrophy, microbial ecology, and adaptations to extreme marine habitats.