Autolysis of Lactococcus lactis ssp. lactis and Lactobacillus casei ssp. casei. Cell lysis induced by a crude bacteriocin.

Autolytic properties of Lactococcus lactis subsp. lactis IFPL359, its Lac Prt derivative Lc. lactis Tl and Lactobacillus casei subsp. casei IFPL731, used as starter and adjunct starter in goat's milk cheese making, have been studied. The lytic effect of a bacteriocin produced by a lactic acid bacterium isolated from raw goat's milk has also been analyzed. Lactococcal cells resuspended in phosphate buffer showed a peak of autolysis when they were harvested in the early growth phase. A more stable autolytic pattern through the exponential growth was obtained for Lb. casei IFPL731. Optimal autolysis was found in 0.1 M sodium phosphate buffer during incubation at 40 degrees C for Lb. casei IFPL731 and at 35 degrees C for the lactococci. Thermoinduction of cell lysis was not obtained in any of the cases under the conditions studied. Lytic effect of the crude bacteriocin assayed was strongest against Lc. lactis Tl. Lysis response to the bacteriocin seemed to be strain-dependent and related to growth conditions.