Apparent Destruction of Nisin by the Producer Organism before Initiation of Growth in Streptococcus lactis

Abstract

WHEN a stationary phase culture of Streptococcus lactis is inoculated into fresh medium, the concentration of the protein antibiotic nisin, carried over with the inoculum, diminishes and a minimum value is reached at the end of the lag phase 1–3 h after inoculation¹. We have recently found a direct correlation between the cellular nisin concentration and the duration of the lag-phase² and so it is possible that the cells have to inactivate the nisin they contain before initiation of fresh growth. This communication deals with the mechanism of the apparent destruction of nisin. Nisinase has been reported in a great variety of micro-organisms³ and Jarvis⁴ suggested that some bacilli contain a non-proteolytic enzyme which converts nisin A into less effective antibiotics (nisin C and E). My results suggest that the inactivation of nisin by the producer organism may not be entirely enzymatic.