Abstract:

This study aimed to screen the suitable strains for vegetable fermentation from six Lactobacillus species
present in pickled vegetable, namely Lactobacillus plantarum, L. fermentum, L. brevis, L. Pentosus, L. mesenteroides and
L. lactics. During culture in an MRS medium containing nitrite, these six strains of Lactobacillus could reduce the nitrite
in the decreasing order: Lactobacillus pentosus > Lactobacillus plantarum > Leuconostoc mesenteroides > Lactobacillus
fermentum > Lactobacillus lactics > Lactobacillus brevis. The fermentation rates of L. plantarum, L. pentosus and
L. mesenteroides, as indicated by pH reduction rates, were higher than those of three other strains. Furthermore, whole-cell
protein electrophoresis indicated that L. plantarum, L. pentosus and L. mesenteroides were the dominant bacteria in cabbage
fermentation. Their applicability as starter cultures for vegetable fermentation was also confirmed based on nitrite-reducing
ability, fermentation rate and viability. Comparing their fermentation characteristics, it was found that the growth cycle
and stationary phase of Leuconostoc mesenteroides were shorter than those of the other two strains, and entered the decline
phase earlier. L. plantarum was more resistant to acids than L. pentosus and L. mesenteroides and Leuconostoc mesenteroides
was more sensitive to acids. The optimal growth temperature for Leuconostoc mesenteroides was 30 ℃ whereas the optimal
growth temperature for both L. plantarum and L. plantarum was 37 ℃. At 15 ℃, the optical density (OD600 nm) of Leuconostoc
mesenteroides was very low, indicating that it is more sensitive to low temperature than L. pentosus and L. plantarum.

Key words: lactic acid bacteria, vegetables, fermentation starter, pickle, inoculated fermentation