Identification of a New Candida Tropicalis Yeast Strain Possessing Antagonistic Activity Against the
The traditional Vietnamese fermented pickles are naturally produced in presence of a
microbial community including lactic acid bacteria and other microbes. Lactic acid bacteria play
important roles in vegetable fermentation, whereas some yeasts have contributions to aromatic
formation. However, the fermented products are sometimes spoiled by contamination of unknown
bacteria during fermentation. In this study, we isolated three bacterial strains including KG 2.2,
KG 2.3 and KG 2.5 in which their growth causes spoilage of the fermented pickles with formation
of white biofilm layers. On basis of morphological and biochemical characteristics, these bacterial
strains belong to Bacillus genus. The results from 16S rRNA gene sequencing indicated that the
strains KG 2.2 and KG 2.5 areBacillus subtilis, KG 2.3 isB. amyloliquefaciens. In addition, we
isolated three antibacterial yeast strains from the high-quality fermentedvegetable samples. These
yeasts are able to strongly inhibit growth of the spoilage bacteria. One of these strains with the best
antagonistic activity named L36 was characterized as Candida tropicalis based on the ITS
sequence of rDNA. This is the first report about Candida tropicalishaving antibacterial activity
against the food-spoilage bacteria. This yeast strain is a good candidate for preservation of
traditional fermented vegetable products as a supplement.