Abstract:

The microbial population, diversity and dynamics of Sichuan pickles with different salt concentrations
were assessed. Using different selective media, 168 microbes were isolated from pickle brines with three different salt
concentrations and identified by 16S rDNA or 18S rDNA analysis. The results showed the lactic acid bacteria Lactobacillus
plantarum and Lactobacillus pentosus dominated the normal process of Sichuan pickle fermentation. When Sichuan pickle
was deteriorated, Bacillus and yeast especially Bacillus subtilis and Candida tanzawaensis were the dominant flora in the
pickle samples. Furthermore, Bacillus methylotrophicus, Bacillus licheniformis, Pichia kudriavzevii and Candida tropicalis
were isolated from pickle brine with 40 g/L salt. Bacillus pumilus, Pichia kluyveri var. cephalocereana and Candida
tropicalis were the most abundant isolates from pickle brine with 60 g/L salt. The major representatives of spoilage-causing
microbes involved in pickle brine with 80 g/L salt were Proteus mirabilis, Bacillus amyloliquefaciens, Galactomyces
geotrichum, Bacillus licheniformis, Pichia kudriavzevii and Pichia kluyveri var. cephalocereana. The biofilms formed on the
surface of spoiled pickle brines consisted of bacteria and fungi. When the salt concentration was higher in the pickle brine,
the more proportion of bacteria existed in the biofilm.

Key words: Sichuan pickles, salt concentration, normal fermentation, spoilage, dominant flora