Bacterial diversity and physicochemical properties of low-salt shrimp paste fermented at different temperatures

Low-salt shrimp paste (LSP) is a new emerging shrimp paste. The specific objective of this research was to investigate the effect of fermentation temperature on the physicochemical properties and bacterial communities in LSP. The results indicated that the content of total volatile basic nitrogen (TVB-N), amino acid nitrogen (AAN), and TCA-soluble peptide in the LSP fermented at different temperatures (10 °C, 15 °C, 20 °C and 25 °C) all exhibited an increasing trend with increasing temperature, while the content of malondialdehyde (MDA) showed a trend of first rising and then falling. High-throughput sequencing showed that the Firmicutes, Actinobacteria, Proteobacteria, Bacteroidetes and Staphylococcus were dominant in LSP fermented at 10 °C, while Firmicutes and Tetragenococcus were dominant in LSP fermented at 25 °C. Furthermore, correlation analysis suggested that IIumatobacter, Staphylococcus and Mycobacterium were positively correlated with the content of TCA-soluble peptide, TVB-N and AAN, while negatively correlated with pH in LSP fermented at 10 °C. Tetragenococcus, Ensifer, Acinetobacter and Weissella were positively correlated with most of the physicochemical properties in LSP fermented at 25 °C. In conclusion, fermentation temperature could significantly affect the physicochemical properties and the bacterial community in LSP. These findings provide a theoretical reference for advancing the thermostatic fermentation of commercial LSP.