Spoilage of refrigerated (4 °C) Litopenaeus vannamei: cooperation between Shewanella species and contribution of cyclo‐(L‐Pro‐L‐Leu)‐dependent quorum sensing |
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Authors: | Suqin Zhu Caili Zhang Haohao Wu Jinxin Jie Mingyong Zeng Zunying Liu Changyun Wang Huicheng Yang |
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Affiliation: | 1. College of Food Science and Engineering, Ocean University of China, Qingdao, Shandong, China;2. School of Medicine and Pharmacy, Ocean University of China, Qingdao, Shandong, China;3. Zhejiang Marine Development Research Institute, Zhoushan, Zhejiang, China |
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Abstract: | The spoilage potential of Shewanella putrefaciens and S. baltica isolated from spoiled refrigerated Litopenaeus vannamei was evaluated by in vitro assays for trimethylamine oxide reduction, extracellular hydrolytic enzymes and biofilm formation, and in vivo inoculation into surface‐sterilised shrimp followed by microbial, biochemical and sensory analyses during storage for 5 days at 4 °C. S. baltica displayed higher spoilage potential than S. putrefaciens both in vitro and in vivo. Shrimp co‐inoculated with them had one‐day shorter shelf life than those mono‐inoculated, based on the results of bacterial density, volatile base nitrogen, trimethylamine, volatile organic compounds and sensory analysis, which strongly suggests cooperation of Shewanella species in shrimp spoilage. Exogenous cyclo‐(L‐Pro‐L‐Leu) boosted bacterial growth, extracellular protease and collagenase activities, and biofilm formation of S. putrefaciens and S. baltica at least before they entered the stationary phase, indicating that cyclo‐(L‐Pro‐L‐Leu)‐dependent quorum sensing, a recently suggested communication mechanism between them, contributes to the cooperation. |
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Keywords: | Bacterial cooperation quorum sensing Shewanella spp shrimp spoilage |
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