Abstract
SUMMARY: A systematic study of the spiral form bacterial flora of oxidation ponds has been made. Three known species, namely Spirillum itersonii, S. serpens and S. volutans, were constantly found. A primary enrichment medium for S. volutans from natural sources is given. A new species has been isolated; its main characters are: strictly aerobic, catalase-positive, does not grow under anaerobic conditions in the presence of nitrate, forms microcysts, differs in carbon-source utilization from previous described species. The species has been named Spirillum peregrinum.