RNA-seq reveals the phage-resistant mechanisms displayed by Lactiplantibacillus plantarum ZJU-1 isolated from Chinese traditional sourdough

Abstract

Seven spontaneous phage-resistant mutants were obtained from a wild-type Lactiplantibacillus plantarum. Phage-resistance stability, efficiency of plaquing (EOP), adsorption rates, lysogeny, growth, and acid production of mutants B4 and B7 were determined. The phage defence mechanism of B4 was revealed by RNA-seq. Both B4 and B7 exhibited very low EOP values and high phage-resistance stabilities. Adsorption rates of B4 and B7 in MRS-Ca broth were diminished to 69.14% and 97.96%, respectively. Technological properties in the presence of phages were similar to the wild-type Lb. plantarum. RNA-seq revealed that genes of B4 were differentially expressed when compared with the wild-type Lb. plantarum. Genes involving in cell surface proteins, phosphoenolypyruvate sugar phosphotransferase system, and EPS production were up-regulated. The phage-resistance of B4 was increased by the downregulation of genes coding for prophages and prophage-induced lysins proteins. The results give clues for a novel strategy of controlling phage contamination in dairy industry.