Correlation Between Microbial Diversity and Volatile Flavor Compounds of Suan zuo rou, a Fermented Meat Product From Guizhou, China

Abstract

Suan zuo rou (SZR), a traditional fermented meat from Guizhou province, China, is loved by local people for its unique flavor and nutritional value. However, the microbial communities and related flavor characteristics of SZR from different regions of Guizhou are unclear. We studied the correlation between the microbial communities and the physicochemical properties and volatile flavor compounds (VFCs) of 15 SZR samples from three regions in Guizhou province. The microbial community structure of SZR was determined by high-throughput sequencing and VFCs were identified by headspace-solid phase microextraction combined with gas chromatography-mass spectrometry. The results indicated that the microbial communities of SZR varied among the regions, as evidenced by the relative abundance of Weissella, Staphylococcus, Brochothrix, Kazachstania, and Debaryomces. There were also significant differences in pH, water activity, NaCl, and total volatile basic nitrogen (P < 0.05). Based on orthogonal projections to latent structures and Pearson's correlation coefficient, we showed that Wickerhamomyces, Kazachstania, Lactobacillus, Weissella, Brochothrix, Debaryomyces, Staphylococcus, Pediococcus, Pichia, Candida, and Leuconostoc were highly correlated with 48 VFCs (| ρ| > 0.8, P < 0.05). Redundancy analysis showed that most of the dominant bacteria were positively related to water activity, whereas Lactobacillus was positively related with pH, and negatively related with total volatile basic nitrogen.

Keywords: correlation; fermented meat; microbial diversity; physicochemical properties; volatile flavor compounds.

FIGURE 1

(A) Variations in microbial diversity and community structure of SZR in three different regions. rarefaction curves of fungi and bacteria for each sample. (B) Shannon index curves of fungi and bacteria for each sample. (C,D) NMDS and PCoA score plots of bacteria and fungi.

FIGURE 2

Relative abundance of bacteria at the phylum (A) and genus (B) level and fungi at phylum (C) and genus (D) of SZR from different regions.

FIGURE 3

(A) Principal component analysis (PCA) and load diagram (B) results for flavor metabolites contents in SZR samples.

FIGURE 4

Heat map of changes in differential compounds of SZR from three different regions.

FIGURE 5

Association network diagram of bacteria and fungi. The orange and green circles refer to bacteria and fungi, respectively, and the red and blue lines refer to positive correlations (r > 0.7 and P < 0.05) and negative correlations (r < −0.7 and P < 0.05), respectively. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article).

FIGURE 6

(A) RDA of microorganisms (Top 10 of OTU) and physiochemical properties. Correlation between physiochemical properties and fungal genera. (B) Correlations between physiochemical properties and bacterial genera.

FIGURE 7

Changes in VIP (pred) values of the top 10 fungi and bacteria by relative abundance at the genus level.

FIGURE 8

Correlation analyses between microorganisms [VIP(pred) > 1.0] and volatile flavor compounds. Statistically significant (P < 0.05) Pearson’s correlation coefficient (| ρ| > 0.8) indicates the robust correlations. The green, orange and purple circles refer to bacteria, fungi and volatile flavors, respectively, and the red and blue lines refer to positive correlations (| r| > 0.8 and P < 0.05) and negative correlations (| r| < −0.8 and P < 0.05), respectively. The size of nodes indicates the degree of connections. The thickness of each connection (edge) between two nodes is proportional to the value of Pearson’s correlation coefficient. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article).