Aims: The study of proteolytic activity and examination of proteinase gene region organization in proteolytically active Lactobacillus plantarum strains from different natural sources.
Methods and results: A set of 37 lactobacilli was distinguished by using multiplex PCR assay. Results showed that 34 strains were Lact. plantarum and three of them were Lact. paraplantarum. The examination of proteolytic activity revealed that 28 Lact. plantarum and two Lact. paraplantarum hydrolyse beta-casein. Further analyses of all proteolytically active Lact. plantarum with primers specific for different types of CEPs demonstrated that strain BGSJ3-18 has prtP catalytic domain as well as prtP-prtM intergenic region showing more than 95% sequence identity with the same regions present in Lact. paracasei, Lact. casei and L. lactis. No presence of prtB, prtH or prtR proteinase genes was detected in any of tested Lact. plantarum strains.
Conclusions: One out of 28 analysed Lact. plantarum strains harbours the prtP-like gene. The other proteolytically active Lact. plantarum probably possesses a different type of extracellular proteinase(s).
Significance and impact of the study: It is the first report about the presence of the prtP-like gene in Lact. plantarum, which illustrates the mobility of this gene and its presence in different species.