Exploring the Fungal Community and Its Correlation with the Physicochemical Properties of Chinese Traditional Fermented Fish (Suanyu)

Suanyu is a traditional natural fermented fish product from Southwest China that contains very complex microflora. The main purpose of this study was to explore the fungal community and its relationship with the physicochemical properties of Suanyu. The fungal community structure of Suanyu from the main provinces (Guizhou and Hunan) was studied via high-throughput sequencing. The correlation between dominant fungi and physicochemical characteristics was analyzed via Spearman's correlation coefficient. The results showed that the pH value, total volatile base nitrogen content, and thiobarbituric acid reactive substance content ranges of Suanyu samples were 4.30-5.50, 17.11-94.70 mg/100 g, and 0.61 to 3.62 mg/kg, respectively. The average contents of total volatile base nitrogen, thiobarbituric acid reactive substance, and total BAs in Suanyu from Guizhou were lower than those from Hunan. The main BAs were phenethylamine, putrescine, cadaverine, histamine, and tyramine. Ascomycota was the dominant fungal phylum, and Kodamaea, Debaryomyces, Wallemia, Zygosaccharomyces, and unclassified Dipodascaceae were the dominant fungal genera in different samples. Moreover, high abundance levels of Kodamaea and Zygosaccharomyces were found in Suanyu from Guizhou. According to the correlation analysis, Kodamaea and Zygosaccharomyces were negatively correlated with TBARS (R-2 = 0.43, 0.51) and TVBN (R-2 = 0.37, 0.29), and unclassified Dipodascaceae was significant negatively correlated with tyramine (R-2 = 0.56). This study expands the understanding of the fungal community and the fermentation characteristics of the dominant fungi in Suanyu.

Automated summary

This study investigated the fungal community and its correlation with the physicochemical properties of Suanyu, a traditional fermented fish product from Southwest China. The results showed that the pH, total volatile base nitrogen content, and thiobarbituric acid reactive substance content of Suanyu samples varied within certain ranges. The dominant fungal phylum was Ascomycota, and Kodamaea and Zygosaccharomyces were the dominant fungal genera in different samples. Moreover, Kodamaea and Zygosaccharomyces were negatively correlated with TBARS and TVBN, and unclassified Dipodascaceae was significantly negatively correlated with tyramine.