Changes in Bacterial Diversity and Dominant Spoilage Bacteria during Storage of Panlongcai, a Traditional Steamed Dish in Zhongxiang, Hubei

The bacterial community composition, its dynamic changes and the dominant spoilage bacteria in Panlongcai at different storage temperatures (4 and 20 ℃ ) were studied using high-throughput sequencing (HTS). The results showed that a total 19 bacterial phyla and 166 bacterial genera were detected in all samples, with the dominant bacterial phyla being Cyanobacteria, Firmicutes, Proteobacteria and Bacteroidetes. The relative abundance of Aeromonas, unclassified Chloroplast, and Paenibacillus changed significantly. Diversity analysis showed that there were significant fluctuations in the abundance of bacteria at the genus level with extended storage, irrespective of storage temperature. The species richness of the bacterial community in Panlongcai stored at 4 ℃ showed an overall increasing trend over 40 days of storage, decreasing in the first 10 days and later increased progressively. During storage at 20 ℃ , the species richness first decreased and then increased with fluctuations, reaching its peak on day 15. Furthermore, in the samples stored at 20 ℃ , the dominant microbial community achieved a competitive advantage in a relatively short period, more pronounced changes in the microbial flora being observed. It was inferred that the spoilage organisms were Aeromonas and Acinetobacter for Panlongcai stored at 20 ℃ , and Aeromonas, Acinetobacter, and Paenibacillus at 4 ℃ . Three Pseudomonas species (P. tohonis, P. juntendi, and P. psychrotolerans) were isolated from Panlongcai under refrigerated conditions, thus presuming that Pseudomonas is potential spoilage organism.