Liu Xiaoxiang, Ye Yifan, Zhu Yin, Wang Lifang, Yuan Leyang, Zhu Junli, Sun Aihua
School of Basic Medical Sciences and Forensic Medicine, Hangzhou Medical College, Hangzhou, China.
Zhejiang Museum of Natural History, Hangzhou, China.
Front Microbiol. 2021 May 31;12:641844. doi: 10.3389/fmicb.2021.641844. eCollection 2021.
is a typical spoiler of proteinaceous foods, and it is characterized by high spoilage activity. The sigma factor RpoN is a well-known regulator controlling nitrogen assimilation and virulence in many pathogens. However, its exact role in regulating the spoilage caused by . is unknown. Here, an in-frame deletion mutation of was constructed to investigate its global regulatory function through phenotypic and RNA-seq analysis. The results of phenotypic assays showed that the mutant was deficient in swimming motility, biofilm formation, and resistance to heat and nine antibiotics, while the mutant increased the resistance to HO. Moreover, the mutant markedly reduced extracellular protease and total volatile basic nitrogen (TVB-N) production in sterilized fish juice at 4°C; meanwhile, the juice with the mutant showed significantly higher sensory scores than that with the wild-type strain. To identify RpoN-controlled genes, RNA-seq-dependent transcriptomics analysis of the wild-type strain and the mutant was performed. A total of 1224 genes were significantly downregulated, and 474 genes were significantly upregulated by at least two folds at the RNA level in the mutant compared with the wild-type strain, revealing the involvement of RpoN in several cellular processes, mainly flagellar mobility, adhesion, polysaccharide metabolism, resistance, and amino acid transport and metabolism; this may contribute to the swimming motility, biofilm formation, stress and antibiotic resistance, and spoilage activities of . . Our results provide insights into the regulatory role of RpoN of . in food spoilage, which can be valuable to ensure food quality and safety.
是蛋白质类食品的典型腐败菌，具有很高的腐败活性。σ因子RpoN是一种著名的调控因子，在许多病原体中控制氮同化和毒力。然而，其在调节由……引起的腐败的确切作用尚不清楚。在此，构建了……的框内缺失突变体，通过表型和RNA测序分析来研究其全局调控功能。表型分析结果表明，……突变体在游泳运动性、生物膜形成以及对热和九种抗生素的抗性方面存在缺陷，而该突变体对过氧化氢的抗性增强。此外，……突变体显著降低了4℃灭菌鱼汁中细胞外蛋白酶的产生和总挥发性盐基氮（TVB-N）的含量；同时，含有……突变体的鱼汁感官评分显著高于野生型菌株。为了鉴定RpoN调控的基因，对野生型菌株和……突变体进行了基于RNA测序的转录组学分析。与野生型菌株相比，……突变体在RNA水平上共有1224个基因显著下调，474个基因显著上调至少两倍，这揭示了RpoN参与了多个细胞过程，主要是鞭毛运动、黏附、多糖代谢、抗性以及氨基酸转运和代谢；这可能有助于……的游泳运动性、生物膜形成、应激和抗生素抗性以及腐败活性。我们的研究结果为……的RpoN在食品腐败中的调控作用提供了见解，这对于确保食品质量和安全可能具有重要价值。
