Promotion of Autolysis in Lactobacilli

The conditions of promotion of autolysis of three strains of Lactobacilli were investigated. The autolysis of L. acidophilus, L. helveticus and L. casei at exponential phase was remarkably enhanced by freezing storage at ?20°C overnight.

The turbidity decrease of L. acidophilus’ cell suspension corresponds to the increase of cell free nitrogen compounds, glucosamine and DNA component. All these compounds were more rapidly released from the cells stored at ?20°C than those stored at 3°C. The cells which were harvested at the exponential phase had higher autolytic activity than those at stationary phase. The storage of the cells at ?20°C for 2 days or more could effectively promote the autolysis.

The activity was increased by Ca²⁺ or Mg²⁺. Optimum pH of the autolytic enzyme of L. acidophilus was 6~7.