Prototrophic Thermophilic Bacillus: Isolation, Properties, and Kinetics of Growth

A thermophilic bacillus (minimal growth temperature 41 C, optimal 55 to 58 C, and maximal 65 C) was isolated from a manure pile. It is very similar to Bacillus stearothermophilus, but it differs in its inability to hydrolyze starch. The thermophilic isolate is a prototroph which grows in a minimal medium consisting of glucose, ammonium salt, phosphate buffer, and inorganic salts. At all temperatures studied (low to high), the same minimal nutritional requirements prevailed. The Arrhenius constant for growth was found to be 15,000 and 13,500 cal/mole in the minimal and rich media, respectively.