Effects of Different Storage Temperatures on Bacterial Communities and Functional Potential in Pork Meat

Abstract

Storage temperature is considered one of the most important factors that affect the microbial spoilage of fresh meat. Chilling and superchilling are the most popular storage techniques on the market, but during transportation, the temperature may reach 10 °C and may even reach room temperature during local retail storage. In the present study, we stored fresh pork meat at different temperatures, -2 °C, 4 °C, 10 °C, and 25 °C. The composition and functional potential of fresh or spoiled meat resident microbes were analyzed based on 16S rRNA gene amplicon sequencing. The microbial composition exhibited high similarity between pork meat stored at -2 °C and 4 °C, with Pseudomonads and Brochothrix being the dominant taxa. Acinetobacter sp., Myroides sp., and Kurthia sp. were markers for spoiled pork meat stored at 25 °C. Both psychrophilic and mesophilic bacteria were observed to grow under a storage temperature of 10 °C, but the overall composition and functional potential based on Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were found to be similar to that of meat stored at room temperature. Our results broaden the knowledge of possible microbial changes in pork meat during storage, transportation, or retail.

Keywords: microbial spoilage; pork meat; temperature.

Figure 1

Effect of storage temperature on the microbial diversity and composition. (A) α diversity. Shannon index was analyzed at the OTU level. ***: indicates p value < 0.001. (B) β diversity. The principal coordinate analysis (PCoA) was performed based on the Bray–Curtis dissimilarity at the OTU level. (C) Microbial composition at the phylum level. (D) Microbial composition at the genus level.

Figure 2

Linear discriminant analysis effect size (LEfSe) analysis of the microbial composition in pork meat. (A) Histogram of the LDA scores reveals the most differentially abundant taxa between fresh pork meat and spoiled pork meat stored at each temperature condition, respectively. Only features with least discriminant analysis (LDA) values > 2 and Padj values < 0.05 are displayed. p, phylum; c, class; o, order; f, family; g, genus; s, species. (B) Cladogram using the LEfSe method, indicating the phylogenetic distribution of bacteria in fresh and spoiled pork meat.

Figure 3

PCoA analysis of the functional potential of microbial communities. (A) PCoA analysis using the Bray–Curtis dissimilarity based on the KEGG Orthology. (B) PCoA analysis using the Bray–Curtis dissimilarity based on KEGG pathways (level 2).

Figure 4

Metabolic pathway profile comparisons between fresh pork meat and spoiled pork meat. (A) Comparison between fresh pork meat and spoiled pork meat stored at −2 °C. (B) Comparison between fresh pork meat and spoiled pork meat stored at 4 °C. (C) Comparison between fresh pork meat and spoiled pork meat stored at 10 °C. (D) Comparison between fresh pork meat and spoiled pork meat stored at 25 °C. Pathway comparisons were performed based on KEGG pathways (level 2).

Figure 5

Spearman’s correlation analysis of the association between the microbial community and functional potential. The red color represents a positive correlation while the blue color represents a negative correlation. *: indicates significant correlation (|r| > 0.6, p < 0.05).