Safety Evaluation and Whole-Genome Annotation of Lactobacillus plantarum Strains from Different Sources with Special Focus on Isolates from Green Tea

Lactobacillus plantarum shows high intraspecies diversity species, and has one of the largest genome sizes among the lactobacilli. It is adapted to diverse environments and provides a promising potential for various applications. The aim of the study was to investigate the safety and probiotic properties of 18 L. plantarum strains isolated from fermented food products, green tea, and insects. For preliminary safety evaluation the L. plantarum strains were tested for their ability to produce hemolysin and biogenic amines and for their antibiotic resistance. Based on preliminary safety screening, four strains isolated from green tea showed antibiotic resistance below the cut-off MIC values suggested by EFSA, and were selected out of the 18 strains for more detailed studies. Initial selection of strains with putative probiotic potential was determined by their capacity to survive in the human GIT using an in vitro simulation model, and for their adhesion to human Caco-2/TC-7 cell line. Under simulated GIT conditions, all four L. plantarum strains isolated from green tea showed higher survival rates than the control (L. plantarum subsp. plantarum ATCC 14917). All studied strains were genetically identified by 16S rRNA gene sequencing and confirmed to be L. plantarum. In addition, whole-genome sequence analysis of L. plantarum strains APsulloc 331261 and APsulloc 331263 from green tea was performed, and the outcome was compared with the genome of L. plantarum strain WCFS1. The genome was also annotated, and genes related to virulence factors were searched for. The results suggest that L. plantarum strains APsulloc 331261 and APsulloc 331263 can be considered as potential beneficial strains for human and animal applications.