Hazard Analysis Of Listeria Monocytogenes In Aquatic Food At Low Temperature And Inhibitory Activity Of New Antibacterial Bacteriocin Compound Fiber

Listeria monocytogenes(LM)is recognized as one of most important four food-born pathogens in the word wild.It has grown with no special nutritional and has a extensive growth temperature(0.4~50 0C)with surviving at 20 0C for about one year.The toxin and biofilm would be stimulated at severe condition such as low temperature.The study was to screen the LM in aquatic food at low temperature and analysis its factor of hazard.To established the growth predictive model of LM at low temperature and for the control of LM in Litopenaeus Vannamei,Oreochromis mossambicus,Venerupis philippinarum at low temperature by the new antibacterial of bacteriocin composite fiber member prepared by electrospinning fiber technique.The major results as follow:(1)Isolation and identification of LM: The sold aquatic food in ZhanJiang were the raw material and tradtional separation method were used combined with new method of double PCR and 16 S rRNA.Three strains of LM were isolated from fresh silver carp,dried fish of Meixiang and instant fish.The analysis about the influence of temperature,salinity,pH,biofilm and LLO on LM resulted that the optimal temperature,salinity were35~37 0C(while has grown in low temperature),1.5%-3.5% and pH were alkaline.Biofilm and LLO were strong in 37 0C.The strong resistence and extensive adaptation were indicated by that the strandard strains were grown well in view of temperature,salinity,pH,biofilm and LLO.(2)Hazard analysis of LM in aquatic: The quantity,biofilm and LLO were as the evaluation index of Hazard analysis in our study to evluate the growth regularity and hazard at low temperature in Litopenaeus Vannamei,Oreochromis mossambicus,Venerupis philippinarum.Results showed Venerupis philippinarum was best for biofilm formation.The optimal temperature for LLO in all substrates was 20 C and existed for a long time in TSA-YE.(3)The growth predictive model of LM in different substrates at low temperature :Establish the growth predictive model of LM at low temperature in Litopenaeus Vannamei,Oreochromis mossambicus,Venerupis philippinarum.Primary model were fitted by Logistic,Gompertz,Weibull and Hill function and the secondry model were fitted by Dave,Arrhenius and Ratkowsky.The modified Gompertz was the optimal primary model inLitopenaeus Vannamei while the modified Logistic was the the optimal primary model in Oreochromis mossambicus and Venerupis philippinarum.The R~2 of both of the two primary model are above 0.98 and standard deviation are below 0.0085.The relationship between maximum specific growth rate(?m)with temperature is suitable for Arrhenius model in Litopenaeus Vannamei,Oreochromis mossambicus,Venerupis philippinarum,and R~2 are 0.9687,0.9507,0.9756.The secondry model of Lag-time(?)and temperature in Oreochromis mossambicus is suitable for Dave model and a square root of Ratkowsky model is suitable in Litopenaeus Vannamei and Venerupis philippinarum.R~2 are 0.9826,0.9618,0.9590.The residual analysis showed the range of ±0.01 while the bias factor and accuracy factor of prediction model were in acceptable range.These results proved that the prediction model were valid and reliable which can provide the theory basis for the effective control of LM at low temperature.(4)The study on the antibacterial of LM by bacteriocin compound fiber: The bacteriocin compound fiber were got by the method that the bactoricion CAMT2 was treated with electrospining rechnique.The FTIR spectroscopy and scanning electron microscope were to detect the structure and shape.The antibacterial and sustained released were detected when bacteriocin compound fiber prepared.Results showed that the most diameter of antibacterial circle was 23.82±0.20 mm when the cncertration of bactoricion was 0.20 mg/mL.The results of FTIR spectroscopy and scanning electron microscope showed that bacteriocin compound fiber were major vesicular structure without regulation.Inhibitory Activity of new antibacterial bacteriocin compound fiber in aquatic food showed that the optimal antibacterial was in Oreochromis mossambicus.