Growth of the cyanobacterium Microcoleus chtonoplastes on sulfide

Abstract

Microcoleus chtonoplastes was grown in batch and continuous cultures in the presence of sulfide. The growth was not inhibited by 0.15 mM sulfide, and under these conditions the specific growth rate observed was 0.032 h−1. At sulfide concentrations exceeding 1 mM growth did not occur. It was demonstrated that growth of M. chtonoplastes at sulfide concentrations exceeding 0.35 mM was predominantly the result of the oxidation of sulfide. The contribution of Photosystem II was low but of paramount importance in anaerobic environments, since no growth occured if this photosystem was selectively inhibited. However, when Photosystem II was blocked, growth occurred with sulfide as electron donor, provided that oxygen was supplied. This illustrates the nutritional function of oxygen for M. chtonoplastes.