Detection of an OmpA-like protein in Vibrio cholerae

Abstract Rhodopseudomonas marina/agilis was enriched from a natural microbial mat by using conditions that favor growth of anoxygenic photoheterotrophs able to fix N₂ rapidly. The isolated bacterium grows more readily on fructose or mannitol than on organic acid carbon sources, requires preformed biotin and thiamine as growth factors, and is extraordinarily motile; growth occurs up to a temperature of approx. 44°C. The photosynthetic pigments of R. marina/agilis are housed in intracytoplasmic lamellar membranes which show the in vivo absorbance characteristics of bacteriochlorophyll a and carotenoids of the normal spirilloxanthin series. In common with other non-sulfur purple bacteria, R. marina/agilis can also grow as an aerobic heterotroph in darkness. Under these conditions, photopigment synthesis is severely repressed. R. marina/agilis requires 1–5% NaCl for optimal growth, and cells grown on N₂ showed nitrogenase activity of >1000 nmol acetylene reduced h/mg dry wt.