Effect of sulfide on growth of marine bacteria.

Severe hypoxia leads to excess production of hydrogen sulfide in marine environments. In this study, we examined the effect of sulfide on growth of four facultative anaerobic marine bacteria in minimal media under anaerobic conditions. The Gram-negative chemolithoautotrophic Marinobacter sp. tolerated sulfide concentrations up to 0.60 mM, with doubling and lag times increasing as a function of increasing sulfide concentration but with no change in maximum culture yields; growth did not occur at 1.2 mM sulfide. Similar results were obtained for the metabolically diverse Gram-negative denitrifying Pseudomonas stutzeri, except that growth occurred at 1.2 mM and culture yields at 0.60 and 1.2 mM sulfide were approximately 10-fold lower than at sulfide concentrations between 0 and 0.30 mM. Increases in doubling and lag times accompanied by an overall 10-fold decrease in maximum culture yields were found for the Gram-negative chemoheterotrophic Vibrio sp. at all sulfide concentrations tested. In contrast, growth of a Gram-positive chemoheterotrophic Bacillus sp. was resistant to all sulfide concentrations tested (0.15–1.2 mM). Our results highlight the variable responses of marine bacteria to sulfide and provide some insight into shifts that may occur in microbial community structure and diversity as a consequence of changes in sulfide levels that are the result of hypoxia.