Identification Of Quorum Sensing AHLs And Influence Of Aquatic Products Spoilage Of Specific Spoilage Organism Isolated From Scophthalmus Maximus During Cold Storage

Aquatic products are rich in nutrients and moisture,which have high soluble protein contents and fragile muscle tissue.Fresh aquatic products are perishable after capture without effective preservation processing.The spoilage of seafood is mainly caused by the bacterial growth,in which the special spoilage bacteria(SSO)play a key role.Though the environment remains a low temperature condition through production,transportation to marketing,some psychrophilic microorganisms also can propagation and result in a decline on the quality of aquatic products.Food spoilage caused great economic losses,resource waste and environmental pollution.Pseudomonas is a common psychrophilic microorganism,which can secrete large amounts of proteolytic enzymes,and this characteristic determines its crucial role in high protein food spoilage.Gram-negative bacteria play important rules in food spoilage,and N-acyl-homonserine lactones(AHLs)are typical signal molecule for Quorum Sensing system.Therefore,this study aimed to select pseudomonas from turbot,which could produce AHLs,and the AHLs was detected utilize Chromobacterium violaceum CV026 and Agrobacterium tumefaciens A136 plate screening model.The influence of different environment conditions on secrete of AHLs by PF-04 was investigated,and quorum sensing system regulation of aquatic products spoilage was analysized.This study aimed to clarify the spoilage mechanisms of fish caused by microorganism,to provide theoretical basis for the development of new seafood preservation techniques based on the targeted inhibition of the spoilage bacteria communication underlying the QS systems.1.Selective media were used to study the initial microflora of turbot stored at 4?.The SSO that produce AHLs were gained utilizing CV026 reported plates,and automatic microorganism identification,drug sensitivity analysis system(VITEK-2)as well as molecular technology based on 16S rRNA were used to identify the dominant spoilage bacteria.Finally the SSO was identified as Pseudomonas fluorescens,and named PF-04.2.The production of AHLs by PF-04 isolated from turbot in different environment condition was investigated.The AHLs production of PF-04 was determined by CV026 bacterial bio-sensors and gas chromatography-mass spectrometry(GC-MS).The results showed the activities of AHLs increased first and then decreased during growth phase,and 25? was beneficial to produce signaling molecules.The different carbon source could significant influence activity of AHLs by PF-04,it was:mannitol>sucrose>maltose>lactose>glucose>fructose>xylose.Higher concentrations of NaCl would inhibit the activity of AHLs,The optimum concentration of NaCl for AHLs produce by PF-04 was 0.5-1.0%.The chemical stability of AHLs was reduced by strong alkaline environment.3.The regulation of quorum sensing AHLs of spoilage factors(biofilm formation,protease and siderophore)was studied.Asprin was selected as quorum sensing inhibitor,and concentration of Quorum Sensing Inhibition(QSI)was 3 mg/mL.Exogenous AHLs increased the biofilm poducton of PF-04,and there was a positive correlation between biofilm production and supplementation of AHLs.Exogenous AHLs could also promote the produce of protease and siderophore of PF-04.QSI could reduce the production of protease and siderophore of PF-04 significantly.4.The AHLs production and spoilage indicators changes were further investigated.Turbot spoilage intervened by QSI was also studied.The production of AHLs of turbot increased first and then decreased during storage period.QSI could reduce the AHLs concentration of turbot,and TVB-N and pH of turbot was reduced by QSI.It showed that QSI could regulate AHLs produce of spoilage bacteria and extend the shelf life of turbot.