Abstract:

Objective: The aim of this study was to isolate and identify lactic acid bacteria able to inhibit Penicillium from
various pickles. The antibacterial activity was determined against the dominant molds in pickles and toxin-producing fungi
and the active compounds produced by the obtained isolates against Penicillium were analyzed. The molecular biological
identification of strains was performed by molecular biological methods. Methods: By the double-layer plate method, lactic
acid bacteria with antimicrobial activity against Penicillium were screened from the pickles. The inhibitory effects of lactic
acid bacteria against fungi from the pickles and mycotoxin-producing fungi preserved in our lab were determined, and the
active substances from lactic acid bacteria were analyzed by protease digestion, pH adjustment and heating. These lactic acid
bacteria were then identified via 16S rDNA sequence analysis after PCR amplification. Results: Three strains were screened
from 14 dominant lactic acid bacterial strains isolated from the pickles for high inhibitory activity against fungi isolated
from the pickles and 2 toxigenic fungi. Treatment with different proteases and pH adjustment had different effects on the
antibacterial activity of the concentrated culture supernatant of lactic acid bacteria, while three heat treatments did not affect
the inhibitory efficiency. Three lactic acid bacteria were identified as L. curvatus, L. sakei and L. plantarum, respectively.
Conclusion: Lactic acid bacteria screened from pickles have high inhibitory activity on Penicillium and some toxigenic
fungi, suggesting that the strains can be used as biological preservative to extend the shelf life of pickles, and its antibacterial
ingredients may be small peptides and/or organic acids.

Key words: pickles, lactic acid bacteria, fungi, antimicrobial component, antibacterial activity