GROWTH OF CHEMOLITHOAUTOTROPHIC SULFUR BACTERIA IN ASSOCIATION WITH THE DISSOLUTION OF AUTHIGENIC CARBONATE ROCKS

Authigenic carbonates at methane seeps are commonly colonized by macroscopic mats of sulfide-oxidizing bacteria. Sulfide-oxidizing bacteria are also abundant in the interstices of authigenic carbonate chimneys in alkaline vent systems. Authigenic carbonates commonly show dissolution textures that could result from acid produced by sulfide-oxidation. Microbially-mediated carbonate dissolution was studied by growing the sulfide-oxidizing bacteria, Halothiobacillus neapolitanus and Thiomicrospira crunogena, in the presence of carbonate rock chips. Dissolution textures were observed in carbonate rocks covered by biofilms of these sulfide-oxidizing bacteria. The bacteria also showed an affinity for growth on the carbonate rocks and incorporated carbonate-derived inorganic carbon under carbon-limited conditions. We hypothesize that sulfide-oxidzing bacteria living attached to carbonate rocks may derive carbon for autotrophic growth from dissolving carbonates, which could prove beneficial under DIC-limited conditions such as at the bottom of an autotrophic biofilm or within DIC-depleted vent plumes.