EMENDED DESCRIPTION OF THERMOSIPHO-AFRICANUS AS A CARBOHYDRATE-FERMENTING SPECIES USING THIOSULFATE AS AN ELECTRON-ACCEPTOR

We found that Thermosipho africanus was able to ferment D-glucose, D-r ibose, maltose, and starch, while D-galactose, fructose, and sucrose w ere utilized poorly. Acetate, H-2, and CO2, as well as small amounts o f ethanol and lactate, were end products of glucose metabolism in this organism. The presence of thiosulfate as an electron acceptor greatly improved growth and increased acetate production from the sugars. The genus Thermosipho is the only genus in the order Thermotogales that h as been described as a non-carbohydrate fermenter. We propose that the description of the genus Thermosipho be emended because the only spec ies in this genus, T. africanus, is a carbohydrate fermenter that is a ble to utilize thiosulfate as an electron acceptor.