Abstract: In this study, one virulent phage of Lactobacillus plantarum WCFS1, named Lpla, was isolated from kimchi. Its characteristics were identified and its spontaneous mutants were screened for resistance to Lpla. The one-step growth curve showed the latency and burst period of Lpla were 15 min and 180 min, respectively and the burst size was 43 PFU/cell. According to its morphology as observed by electron microscopy, Lpla belonged to the Siphoviridae family (morphotype B1). Phage Lpla was highly tolerant to acid and alkali but not to ethanol, heat or UV. The highest adsorption rate of Lpla on the host cell surface was observed at 4 ℃ and the adsorption was improved by the addition of Ca2+ and/or Mg2+. Phage Lpla could adsorb to thermally killed cells, but the adsorption rate was decreased by 20%. Six non-lysogenic Lpla-resistant mutants with genetic stability were obtained. This study provides a theoretical basis for preventing and control phage infection and for developing phage-resistant strains.

Key words: Lactobacillus plantarum, virulent phage, biological characteristics, phage-resistant mutants