Effects of different temperatures on bacterial diversity and volatile flavor compounds during the fermentation of suancai, a traditional fermented vegetable food from northeastern China

The bacterial diversity and volatile flavor compounds (VFCs) during suancai fermentation in different temperatures were investigated by Illumina Hiseq sequencing and GC-MS. Firmicutes and Proteobacteria were observed to be the dominant phyla during the fermentation. Lactobacillus, Serratia, Leuconostoc, Pseudomonas, Pseudomonas, Pediococcus, etc., were observed as the main genus. Serratia and Pseudomonas predominated the early stage of suancai fermentation, while Lactobacillus predominated the later stage. Leuconostoc predominated the fermentation at 10 degrees C and 15 degrees C, while Weissella and Lactococcus predominated at 20 degrees C and 25 degrees C. A total of 86 VFCs were detected in all suancai samples. With the increase of the fermentation temperature, the kinds of VFCs were also increased. Lactobacillus, Pediococcus, Lactococcus, Brochothrix, Psychrobacter, Pseudoalteromonas, Acinetobacter and Enterobacter were the important bacteria related to VFCs during the fermentation. The bacteria were highly correlated with the VFCs in suancai fermentation. As the most dominant genus, Lactobacillus was significantly positive correlated with 13 VFCs. The correlation between the bacteria and VFCs in suancai could be used to search for microbial markers. In conclusion, 20 degrees C could accelerate the maturation and improve the sensory quality of suancai. This study could provide useful guidelines for screening of strains that contribute to the flavor formation in suancai fermentation.