Isolation and Characterization of a Protease-Producing, Thermophilic, Anaerobic Bacterium, Thermobacteroides leptospartum sp. nov.

Abstract

A new thermophilic and anaerobic bacterium, Thermobacteroides leptospartum sp. now., which produces extracellular proteases was isolated from cattle compost. This organism is a Gram-negative, non-sporulating, non-motile and obligately anaerobic filamentous bacterium. Ultra-thin sections of the cells reveal a multilayered envelope structure. The major cellular fatty acids are n-C_16:0 (27.7%), iso-C_17:0 (18.5%) and iso-C_15:0 (16.4%). No hydroxy fatty acids were detected. The temperature range for growth is between 45°C and 71°C, with optimum growth at 60°C; the pH range for growth is between 6.7 and 8.9 at 60°C with a doubling time of 8.6 hr. Various carbohydrates, but not fructose or sucrose, are fermented. The major fermentation products from glucose are ethanol (14.1 mm) and acetate (8.8 mm). Growth is inhibited by polymyxin B, neomycin and gentamicin. The DNA base composition is 43±2mol% G + C.