Suree Nanasombat, Saranya Phunpruch, and Thitirut Jaichalad

pp. 255 - 262

Abstract

The number of lactic acid bacteria (LAB) was analyzed from 52 samples of raw seafoods (shrimp and mussel), and
Thai fermented seafood products including fermented shrimp (kung-jom), mussel (hoi-dong), and fish (pla-jom). The viable
LAB were 3.0×10³ to 3.4×10⁸
 CFU/g. LAB were isolated and screened for their inhibitory activities against eight indicator
bacteria by agar spot test. Among all selected LAB isolates, 52 isolates showed strong inhibitory activity. They were further
characterized for their ability to resist hydrochloric acid, lactic acid, bile salts, and sodium chloride, and their ability to
produce bacteriocins and amino acid decarboxylase. The selected LAB isolates, 1IS11 and 4IS17, were bacteriocin-producing
strains, and showed no amino acid decarboxylase activity, which was suitable property for starter cultures. The isolate 1IS11
could resist both hydrochloric and lactic acid at the lowest pH of 2.0, while the isolate 4IS17 was able to tolerate hydrochloric and lactic acid at the lowest pH of 1.5 and 2.0, respectively. Both isolates could grow in MRS broth containing a high
concentration of sodium chloride (10 %) and bile salts (1.5%). They were identified by morphological characterization, biochemical test, and 16S rDNA sequence analysis. The isolate 1IS11 was found to be Enterococcus faecium, whereas the isolate
4IS17 was Enterococcus faecalis.