Correlation between microbial diversity and biogenic amines during the fermentation processing of grasshopper sub shrimp paste

Fermented foods play an important role in a healthy and balanced diet. Grasshopper sub shrimp paste is an important traditional fermented aquatic product in Asia. In this study, the bacterial and fungal diversity in grasshopper sub shrimp paste taken at different fermentation times were comprehensively analyzed, while the pH, colony count, salinity, TVB-N and the contents of biogenic amines were quantitatively determined. In addition, the correlations among the samples with respect to microbial communities and the different parameters investigated were also established. By combining the results of spearman correlation heatmap with the content of BAs produced by the halotolerant bacteria isolated from the grasshopper sub shrimp paste, six major groups of bacteria (Jeotgalibaca, Jeotgalicoccus, Lysinibacillus, Sporosarcina, Staphylococcus, and Psychrobacter ) were found to be positively correlated with BA production level, suggesting that these bacteria might have a strong tendency to produce BA. Other bacteria such as Lentibacillus, Pseudomonas, and Salinicoccus were negatively correlated with BAs and therefore, they were considered as poor BA producers. The grasshopper sub shrimp paste was characterized by a relatively high abundance of Tetragenococcus, which was the absolute dominant genus during the fermentation process, and it also produced a relatively high level of BA, but was negatively correlated with BA as revealed by the correlation heatmap analysis. Analysis of the species relevance network in grasshopper sub shrimp showed that the actual production of BA by a certain strain was not only affected by the different environments, but was also closely related to other species present in the complex fermentation system.