关键词: 大黄鱼, 希瓦氏菌, 假单胞菌, 黏附特性, 生物膜

Abstract: Three Shewanella sp. strain and three Pseudomonas sp. strains isolated and purified from iced Pseudosciaena crocea were evaluated in this study for their surface hydrophobicity, auto-aggregation ability and biofilm formation ability together with their correlation with adhesion characteristics to fish mucus (gut, gill and surface). Meanwhile, the characteristics of biofilm formation were investigated under different conditions. The results showed that compared with Pseudomonas sp., Shewanella sp. had stronger surface hydrophobicity and auto-aggregation ability and enhanced ability to adhere to fish mucus and form biofilm. Principal component analysis (PCA) and clustering analysis (CA) showed an inter-genus difference but intra-genus similarity in bacterial adhesion ability. Both the auto-aggregation ability and biofilm formation ability were highly correlated with the adhesion ability to gut and gill mucus, while the surface mucus adhesion ability was correlated exclusively with the biofilm formation ability. In addition, biofilm formation was related to initial concentration, incubation time, temperature, pH, NaCl concentration and other environmental factors. The spoilage bacteria formed biofilm rapidly from 12 to 24 h of culture and biofilm biomass reached the highest peak at 36 h, and then gradually reduced with incubation time. The optimum conditions for biofilm formation by Shewanella were as follows: bacterial suspension greater than 106 CFU/mL, temperature 37 ℃, NaCl concentration 0.8% and pH 7–8. Biofilm formation was significantly influenced by fish mucus. Gill mucus promoted biofilm formation, whereas the opposite effect was true for gut mucus.

Key words: Pseudosciaena crocea, Shewanella sp., Pseudomonas sp., adhesive properties, biofilm