The Regulatory Role of Quorum Sensing-Mediated Amino Acid Metabolism in Biofilm Formation and Motility of Hafnia alvei H4

The spoilage phenotype of microorganisms is a key mechanism leading to food spoilage, but how their metabolic environment affects the spoilage phenotype remains unclear. This study utilized metabolomics and spoilage phenotype analysis to reveal metabolic differences between different quorum sensing (QS) genotypes of <i>Hafnia. alvei</i> H4 and their impact on spoilage phenotypes. Ultra-high performance liquid chromatography-fluorescence detection revealed that the QS system participated in the differential metabolic regulation of eight amino acids, with serine exerting the most significant influence on the spoilage phenotype. Subsequent studies demonstrated that QS-promoted serine inhibited bacterial motility by affecting the biosynthesis of rhamnolipid (rather than c-di-GMP) and inhibiting flagellar/chemotactic genes expression. Moreover, QS-promoted serine induced the difference of bacterial inner membrane, further inhibiting bacterial motility. These findings provided fundamental information for the control of biofilms conformation within complex food nutritional background.