Decoding the flavor regulation mechanism of fermented sausages inoculated with indigenous strains via metagenomic and GC-MS analysis

The objective of this study was to elucidate the effects of indigenous strains (Lactiplantibacillus plantarum CQ01107 and Staphylococcus simulans CD207) on flavor profile in fermented sausages, and to reveal the regulation mechanisms via metagenome sequencing. Notably, higher levels of free amino acids and fatty acids were detected in the inoculated group. The L. plantarum and S. simulans possessed stronger protease and lipase activities, respectively. A total of 39 volatile flavor compounds were identified, with those in the inoculated groups being more abundant, particularly in the mixed starter group. Metagenomic sequencing revealed that the indigenous strains were capable of modifying the abundance and composition of bacterial communities by inhibiting the growth of undesirable microorganisms, such as Weissella spp., and promoting the colonization of favorable strains, including Lactobacillus spp. Inoculation with L. plantarum was found to be more favorable for carbohydrate metabolism, while S. simulans contributed more to lipid metabolism. Additionally, inoculation with the above two strains had a similar effect on the abundance of genes related to amino acid metabolism in fermented sausages. The findings contribute to improve the understanding of the mechanisms of flavor formation regulated by starters.