Cultivation of Organisms Concerned in the Oxidation of Thiosulfate

Although numerous investigations deal with the isolation and description of bacteria which decompose thiosulfate and other incompletely oxidized sulfur materials, considerable confusion still exists concerning certain aspects of the nutrition of these bacteria and the significance of the sulfur materials in their development. The present report includes studies on the influence of envi-ronmental conditions upon the development of some bacteria which up to this point at least would be classified as species of the genus Thiobacillus, Beij. The cultures used in these studies have been previously described in some detail (Starkey, 1934a). They may be briefly characterized as follows. They are all Gram-negative, non-sporulating, small, rod-shaped bacteria. Th. novellus increases the acidity of mineral media containing thiosulfate and develops a uniform turbidity of the solution. This is a facultative autotrophic organism. It was described as a new species in the precedingreport (Starkey, 1934a). Culture B is closely related to the bacteria described by Traut-wein (1921; 1924) and called Th. trautweinii, Bergey. It was fortunate that two of Trautwein's three cultures were available in this laboratory, having been supplied by their discoverer over ten years ago. Since that time they have been regularly trans-ferred on nutrient agar. They show the same general character-istics originally ascribed to them. Their original identification as cultures T and K have been retained in this report. Culture B, isolated in this laboratory and T and K grow well on most of