USE OF LACTOBACILLUS-PLANTARUM LPCO10, A BACTERIOCIN PRODUCER, AS A STARTER CULTURE IN SPANISH-STYLE GREEN OLIVE FERMENTATIONS

Bacteriocin-producing Lactobacillus plantarum LPCO10 and its non-bacte riocin-producing, bacteriocin-immune derivative, L. plantarum 55-1, we re evaluated separately for growth and persistence in natural Spanish- style green olive fermentations. Both strains were genetically marked and selectively enumerated using antibiotic-containing media. Plasmid profile and bacteriocin production (bac(+)) were used as additional ma rkers. When olive brines were inoculated at 10(5) CFU/ml, the parent s train, LPCO10, proliferated to dominate the epiphytic microflora, shar ing high population levels with other spontaneously occurring lactobac illi and persisting throughout the fermentation (12 weeks). In contras t, the derivative strain could not be isolated after 7 weeks. Stabilit y of both plasmid profile and bac(+) (LPCO10 strain) or bac(-) (55-1 s train) phenotype was shown by L. plantar nm LPCO10 and L. plantarum 55 -1 isolated throughout the fermentation. Bacteriocin activity could be found in the L. plantarum LPCO10-inoculated brines only after ammoniu m sulfate precipitation and concentration (20 times) of the final brin e. Spontaneously occurring lactobacilli and lactic coccus populations, which were isolated from each of the fermenting brines studied during this investigation, were shown to be sensitive to the bacteriocins pr oduced by L. plantarum LPCO10 when tested by the drop diffusion test. The declines in both pH and glucose levels throughout the fermentative process were similar in L. plantarum LPCO10- and in L. plantarum 55-1 -inoculated brines and were comparable to the declines in the uninocul ated brines. However, the final concentration of lactic acid in L. pla ntarum LPCO10-inoculated brines was higher than in the L. plantarum 55 -1-inoculated brines and uninoculated brines. These results indicated that L. plantarum LPCO10 may be useful as a starter culture to control the lactic acid fermentation of Spanish-style green olives.