Isolation and characterization of Pseudomonas fluorescens producing biogenic amines: AHL-mediated quorum sensing as a key regulatory mechanism
Hongwei Zhan, Xuchen Li, Xiang Zou, Guofeng Qu, Lixiu Zhang, Yanqing Li, Jiao Li, Yongjun Sun, Wenming Ju, Mengqi Ye, Yang Deng, Ting Ding
Abstract
Aquatic products are highly susceptible to contamination by bacteria such as Pseudomonas fluorescens , which produce toxic biogenic amines (BAs) that pose serious risks to food safety and human health. The quorum sensing (QS) of P. fluorescens regulates its spoilage characteristics using N -acyl homoserine lactones (AHLs). Since BAs serve as key indicators of spoilage extent, AHLs may regulate BA production. Understanding the regulation of BA production by AHLs is critical for improving food quality and safety. This study screened and identified BA-producing P. fluorescens strains and constructed a luxI gene-deficient strain (Δ luxI ). The effects of various exogenous AHLs on BA and QS molecule production of different strains were evaluated in both culture medium and refrigerated salmon fillets. Results showed that the Δ luxI mutant exhibited significantly reduced BA production and impaired QS phenotypes. Further analysis revealed that the luxI gene primarily impacts amino acid metabolism, carbohydrate metabolism, and related pathways, leading to changes in BAs. This study elucidates, for the first time, the regulatory mechanism of AHLs on BA production, providing new ideas for controlling BA-producing P. fluorescens in aquatic products. These findings have significant implications for developing novel strategies to mitigate BA production and improve food safety. • P. fluorescens that produce BAs were screened and identified. • The QS system luxI gene-deficient strain was constructed. • The significant change in AHL level affects the production and variety of BAs. • Changes in AHL levels significantly affect QS-related phenotypes. • LuxI gene significantly affects key genes and pathways involved in BAs production.