Marine sponges as habitats of anaerobic phototrophic bacteria

Enrichment cultures were prepared with different media for phototrophic bacteria from four species of marine sponges, collected from oxic coastal waters near Split (Yugoslavia). We obtained pure cultures of six strains ofChromatiaceae and two strains ofRhodospirillaceae by agar shake dilution. TheRhodospirillaceae were identified asRhodopseudomonas sulfidophila and a marine form ofRhodopseudomonas palustris. TheChromatiaceae were identified asChromatium vinosum, Chromatium gracile, Chromatium minutissimum. Ectothiorhodospira mobilis, and a Chromatium species, which in some respects resemblesChromatium minus. The occurrence of strictly anaerobic phototrophic bacteria in aerobic sponges is discussed with respect to nutrition and possible syntrophism.