Inactivation Of Phaget4 As Indicator By High-pressure Or Thermal Treatment

In this paper studied the inactivation characteristics of phageT4 by temperature and ultra high pressure, used gray correlation to analysis the impact of every factor to phageT4, established the survival dynamic model of phageT4 during preservation, and discussed the best method of preservation.The results are as follows:First, analyzed the survival capacity of phageT4 under different storage temperature, and combined with principle of chemical dynamics to establish dynamic model in PBS and nutrient broth. Compared the decay rate constant of phageT4 and found that phosphate buffer was benefit to preserve phageT4. Dynamic model of survival in PBS was: N 1 No1ek nt=?(Kn1=36.83e-18780/RT); Dynamic model of survival in nutrient broth was:N 2 =N o 2 e ?k nt(Kn2=1721.5e-25931/RT). The best preservation method was stored in phosphate buffer under 4℃.However, in order to reduce the experiment time it also could be stored in nutrient broth under 4℃.Second, studied the inactivation of phageT4 in different liquid medium, the results are:1) Less than 60℃the inactivation of phagT4 was not satisfactory. The temperature required to kill phageT4 needing more than 60℃. The linear fitting degree to the inactivation curve of phageT4 was small, and the inactivation law deviated from first-grade kinetic curve. When above 60℃, significant difference between inactivation of phageT4 in three different medium (p=0.00879,p<0.05).Sodium chloride to the inactivation of phageT4 by temperature was significant (p=0.025, p<0.05), and in a certain range of concentration, sodium chloride had a protective effect of phageT4. Different pH values on the inactivation of phageT4 had a significant difference (p=0.045, p<0.05), and acidity was an important inactivated factor of phageT4 by temperature.2) There was a threshold on the inactivation of phageT4 by pressure. Less than 250MPa, the impact of pressure for the inactivation of phageT4 was limited (p=0.14, p>0.05), and more than 250MPa, the impact of pressure for the inactivation of phageT4 was remarkable (p<0.05). The inactivation of phageT4 by pressure in three different medium was significant. Less than 200MPa, the impact of the concentration of sodium chloride to the phageT4 was not significant (p=0.056, p>0.05). Different pH values on the inactivation of phageT4 had significant difference (p=0.0087, p<0.05), and acidity was an important inactivatied factor of phageT4 by pressure.3) During the process of inactivation by pressure and thermal, pressure played a positive role to the inactivation of phageT4 under 60℃, and temperature played a positive role to the inactivation of phageT4 when the temperature higher than 60℃. The acidity enhanced the effect of pressure to the inactivation of phageT4.Third, using gray correlation discussed the factors during process of high pressure collaborative temperature treatment to phageT4. When the temperature was higher than 60℃, the relational order in PBS were: Temperature >pressure induction > treatment time; the relational order in different pH values solutions were: temperature > pH values >pressure induction > treatment time.Fourth, studied the inactivation of phageT4 by pressure and thermal in shells, the results are:1) The shell slurry had protective effect on the inactivation of phageT4 by thermal in shell slurry, and the inactivation rate was higher than in full shells. Dure the treatment process had the same results.2) The treatment by thermal and pressure could increase the production of white shell. The production after treatment by pressure was 19.1% more than untreated shells and the production after treatment by temperature was 6.3% more than untreated shells by. The pH value increased after treatment by thermal or pressure, and the increment was 0.03～0.1.3) After pressure treatment .the shape of plaque became irregular, showing jagged edges, and there were many small plaques.