Isolation and identification of bacteriocin-producing lactic acid bacteria from plants in Mount Makiling Forest Reserve, Philippines

Abstract

Sixty-three lactic acid bacteria (LAB) were isolated from trapped or stagnated water in parts of 14 different plant species in Mount Makiling Forest Reserve, Philippines and were screened for bacteriocin production. Thirteen of these isolates were found antagonistic to different indicator bacterial strains through direct assay. However, after screening of the pH neutralized culture supernatant using ‘spot-on-lawn’ method against Enterococcus faecium 79 as the indicator strain, only one isolate, designated as ML 258, was confirmed to be bacteriocin-producer. Its crude extract of bacteriocin exhibited inhibitory activity against E. faecium and Lactobacillus aciclophilus. The isolate was characterized and found to be gram-positive short rods that occurred in pairs, singly or in chains, catalase negative, microaerophilic, non-motile, non-spore forming and exhibited a heterofermentative type of fermentation. This isolate was obtained from fern (Microsorum longissimus) and was identified as Carnobacterium piscicola using API 50 CHL kit with good identification of 98%. However, the 16S rRNA gene sequencing and homology search from NCBI database using the BLAST program showed that the isolate is 93-95% similar with Carnobacterium maltaromaticum. On the other hand, phylogenetic analysis using MEGA 5 software that constructed a neighbor joining tree thru bootstrap method revealed that this isolate showed more similarity with Enterococcus sp.