Autolysis of Lactococcus lactis MG1363 induced by growth inhibitors

Abstract:

[Objective] Autolysis is a physiological accommodation of bacteria to lyse themselves under stress conditions. The aim of this study is to investigate comprehensively the autolysis of the lactic acid bacteria (LAB) strains stressed by various growth inhibitors. [Methods] The methods include the autolysis assay of of LAB strains with various origins, as well as the determination of autolysis profiles of Lactococcus lactis MG1363 under the conditions specified by different growth media and inhibitors’ interference. [Results] The results showed that the autolysis of L. lactis MG1363 could be induced in glucose strictly-limited medium through the action of ampicillin (Amp), and this phenomenon could only occur at the glucose exhausting point, indicating a growth phase-dependent pattern. And concomitantly, the expression of four predominant autolysins was significantly altered to a variable extent upon the addition of Amp. Furthermore, all the tested inhibitors negatively affected MG1363’s autolysis under non-nutrient conditions, probably suggesting a mode of co-regulation between cell wall synthetic and hydrolytic enzymes. [Conclusion] Collectively, a significant discrepancy was proposed with respect to the autolysis of LAB strains administered with different inhibitors, and moreover, this peculiar phenomenon was strictly nutrition-and growth phase-dependent.