期刊
INTERNATIONAL JOURNAL OF FOOD MICROBIOLOGY
卷 270, 期 -, 页码 31-38出版社
ELSEVIER
DOI: 10.1016/j.ijfoodmicro.2018.02.011
关键词
Pseudomonas fluorescens; RpoS; Stress resistance; Quorum sensing; Food spoilage
资金
- National Natural Science Foundation of China [31501581, 31471639]
- Zhejiang Provincial Program for the Cultivation of High-level Innovative Health Talents
- Professional Development Program for Domestic Visiting Scholars in Chinese Colleges and Universities [124]
Microorganism activities are considered the main cause of most food spoilage, leading to great economic losses. Pseudomonas fluorescent is a Gram-negative bacterium that is widely found in food and has high spoilage activity. RpoS is considered an important global regulator involved in stress survival and virulence in many pathogens. Thus, it is very possible that RpoS plays an important role in spoilage regulation in P. fluorescent. In this study an in-frame deletion mutation of rpoS was constructed to explore its function in P. fluorescent. The results showed that RpoS positively regulated the resistance of P. fluorescent to H2O2, heat, ethanol and crystal violet, negatively regulated the resistance to acetic acid, and had no effect on the resistance to NaCl. Further studies indicated that acylated homoserine lactone (AHL) production and the transcription levels of five AHL-related genes were significantly decreased in the rpoS mutant compared with those in the wild-type strain. Interestingly, the two homologous genes coding for AHL synthases contained RpoS-dependent -10 elements, suggesting that AHL quorum sensing is directly regulated by RpoS. RpoS also contributed to the spoilage activities of P. fluorescent by regulating extracellular protease and total volatile basic nitrogen (TVB-N) production in sterilized salmon juice. Our results reveal that RpoS was a key regulatory factor involved in stress resistance, the AHL quorum sensing system, and spoilage potential of P. fluorescent. Our study may benefit food safety control and food preservation.
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