Microbial community changes induced by a newly isolated salt-tolerant Tetragenococcus muriaticus improve the volatile flavor formation in low-salt fish sauce

Application of low-salt fish sauce is restricted by its easy spoilage and poor flavor formation. In this study, a salt-tolerant strain Tetragenococcus muriaticus with powerful salt tolerance was isolated as starter for the low-salt fish sauce fermentation. The 16S rRNA gene high-throughput sequencing showed that Staphylococcus was the main microbial genus at the beginning of fermentation, reaching 73.75%, followed by Tetragenococcus (16.36%) and Pseudomonas (6.68%), while Tetragenococcus quickly took over the dominant position with the relative abundance over 56.9% after 10 d fermentation and peaked at the end of fermentation. There were a total of 144 volatile compounds identified by HS-SPME-GC-MS, among which aldehydes, esters, alcohols, heterocycles, ketones, and acids were the main volatile flavor compounds and were mainly produced by Tetragenococcus, Synechococcus, Rhodococcus, Stenotrophomonas, Achromobacter, and Brucella based on the correlation network maps constructed by the Pearson’s correlation coefficient after O2PLS evaluation. The Sobs, ACE, Chao, and Shannon indexes of microbial community were significantly reduced, while the Simpson index was markedly enhanced in the low-salt fish sauce fermented with T. muriaticus compared with them in the fish sauce without starter addition. The addition of T. muriaticus also obviously improved the types and concentrations of main volatile flavor compounds in the low-salt fish sauce. The correlation network map showed that Tetragenococcus was the only genus that played a crucial role in the spoilage microorganism inhibition and volatile flavor improvement in the fish sauce. T. muriaticus can be developed as a potential microbial starter for the industrial production of low-salt fish sauce.