Isolation and characterization of a bacteriocin produced by Bacillus stearothermophilus strain NU-10.

Broth-grown cultures of Bacillus stearothermophilus strain NU-10 produce a bacteriocin which exerts lethal activity on other strains of the bacterium. Optimal production occurs during late maximum stationary phase of growth, at neutral pH, and 55-65 degrees C. The bacteriocin can be substantially purified by a combination of precipitations, centrifugations, and gel filtrations. The thermocin is composed of protein and carbohydrate. It is partially destroyed by proteolytic enzymes but is resistant to DNase, RNase, and various chemical treatments. The bacteriocin has a small molecular weight and exhibits considerable thermostability.