selection and identification of lactic acid bacteria that inhibit yeast contaminants isolated from fermented plant beverages

In order to investigate yeast contamination in finished products of fermented plant beverages (FPBs), 27 FPBs samples were collected from northern Thailand. Nine samples from finished products werecontaminated with yeast and 36 yeast isolates were isolated and identified to the genera level by conventional methods. These included 12 isolates of Rhodotorula sp., 9 isolates of Pichia sp., 9 isolates of Hansenula sp.,3 isolates of Saccharomyces sp. and 3 isolates of Candida sp. Rhodotorula sp. was chosen to use as a target organism for the primary screening of lactic acid bacteria (LAB) with antiyeast activity, using a dual cultureoverlay assay. Fifteen of the 72 LAB cultures isolated from Thai fermented foods and the FPBs produced a strong inhibition against the Rhodotorula sp. Ten of these also had a broad antiyeast spectra (at least 5genera inhibited). Three of the isolates that gave the best inhibition (DW1, 3 and 4) were identified as Lactobacillus plantarum strains based on conventional identification methods.