Diversity and succession of microbial communities and chemical analysis in dried Lutianus erythropterus during storage

The population, diversity and succession of microbial communities and chemical characteristics of dried crimson snapper (Lutianus erythropterus) during storage for 50 days were investigated. The population of bacteria, yeasts and filamentous fungi in the samples were enumerated by culture methods using appropriate agar media. The amplicons of the 16S rRNA of bacteria and the ITS region of fungi were sequenced and compared with gene libraries to obtain the identity and abundance of microorganisms in the community. Free amino acids and several other chemical characteristics were determined by HPLC and corresponding chemical reaction methods. Before storage, the average counts of bacteria, yeasts and filamentous fungi in the dried fish were 3.2, 2.5 and 2.2 log CFU/g, which increased to 4.6, 3.6 and 3.9 log CFU/g, respectively after storage. Major succession in the bacterial > fungal communities occurred during storage as evidenced by a significant decline in the number and diversity of microbial communities. Predominant bacterial genera were Phytobacteria, Vibrio, Acinetobacter and Macrococcus in the freshly dried fish, which were replaced by Bacillaceae, Halomonas, Lentibacillus, Alkalibacillus after storage. The fungal community of the freshly dried fish consisted of Penicillum > Yamadazyma, Malassezia, Candida and Eurodales with Penicillum being the most dominant. Penicillium camemberti was the most abundant fungal species in the dried fish before storage with most dominant after storage and accounted for > 96% of the abundance. The succession in the microbial community was accompanied by major changes in chemical characteristics with a significant decrease in fat, and an increase in total free amino acids and total volatile basic nitrogen (TVB-N).