Some observations on the culture,physiology and morphology of some brown-redRhodospirillum-species

Summary From ditch- and canalwater 21 strains of brown-red, photo-synthetically active spirilla were isolated. These spirilla distinguished themselves fromRhodospirillum rubrum by the composition of their pigment complex and by their behaviour towards oxygen (strictly anaerobic). The strains, judged by morphological characteristics, represented three different species. Two of the species could be identified withRhodospirillum fulvum van Niel resp.Rhodospirillum photometricum Molisch. The third species was found to be a new one, for which the nameRhodospirillum Molischianum was proposed.Regarding the isolation, culture, morphological and physiological characteristics of these organisms detailed data were given. Various organic substances can function as H-donors for these spirilla. The absorption spectra of living cells of the three species show a striking conformity, but there is a distinct difference between the absorption spectra of the brown-redRhodospirillum-species and the absorption spectrum ofRhodospirillum rubrum. The results of a chromatographical analysis of the pigment complex of one of the strains ofRhodospirillum pholometricum make it probable that this difference is due to the absence of the carotenoid spirilloxanthin in the brown-red spirilla.