Production and mode of action of lactocin 27: bacteriocin from a homofermentative Lactobacillus.

Lactobacillus helveticus strain LP27 produced a bacteriocin, lactocin 27, in dialyzable and nondialyzable forms. No evidence was obtained to indicate that lactocin 27 was under the control of extrachromosomal plasmids. Lactocin 27 had a bacteriostatic effect on the indicator, Lactobacillus helveticus strain LS18. It inhibited primarily protein synthesis without affecting deoxyribonucleic acid and ribonucleic acid synthesis or adenosine 5'-triphosphate levels. Treatment of susceptible cells with the lactocin did not cause leakage of ultraviolet-absorbing material, but caused the efflux of potassium ions and the influx of sodium ions. It adsorbed non-specifically to various bacterial species irrespective of their susceptibility to lactocin 27. However, the presence of specific receptors has not been ruled out.