Research article

ANTAGONISTIC EFFECT OF DIFFERENT DEGREE TEMPERATURE AND SALT CONCENTRATION FOR INACTIVATING ESCHERICHIA COLI O157:H7 IN MILK PRODUCT (COW AND BUFFALO)

Nada Gasid Shlash, Hikmat Al-Nassir, Ali H. Fadhil

Online First: October 29, 2022


The current study is one of the first studies in Kerbala governorate, which aims to isolate, diagnose and spread of E. coli o157:H7 and study the effect of temperature and salt concentrations on milk products for cows and buffaloes from the growth of pathogenic E. coli o157:H7. This study included three parts, where 240 samples were collected, form cow and buffalo milk and their milk products , the experimental work, which illustrate the effect of temperature on E.coli O157:H7 found a significant increase in bacterial growth when observed in all dilutions (treatment (3) at 20 c for (24) hours) (80 , 80 ,3 , 3 and 2) (Treatment (4) at 30 c for (12) hours) (1150 , 943 , 387 , 70 , 5 and 4) and also in (Treatment (5) at 37 c for (12) hours ) (1200 , 1005 , 420 , 95 , 16 and 3 ) the last treatment (6 )at 43 c for 12 hours ) (995 , 821 , 133 , 17 and 8) in the dilution ( 10-1 , 10-2 , 10-3 , 10-4 ,10-5 and 10-6 ) respectively and comparing all treatment groups vertically and each for dilutions, there were high significant differences in the growth of numbers of bacteria E.coli O157H7 in a (treatment 3 , treatment 4, treatment 5 , treatment 6 ). The result of the study also showed that using concentration of (1 %) NaCl had significant increased growth in treatment ( 2) at 20 c for (24) hours (600 , 291 , 11 , 7 , 1 and 1 ) cfu in dilution (10-1 , 10-2 , 10-3 , 10-4 , 10-5 and 10-6 ) respectively . While showing the treatment concentration of 5% NaCl at (20 c for 24 hours) high growth of E.coli o157:H7 (490 , 395 , 51 , 6 and 1) cfu in dilution (10-1 , 10-2 , 10-3 , 10-4 and 10-5), And at salt levels in 9% NaCl at (37c for 12 hours) Bacterial growth was observed in the dilutions (700 , 680 , 100 ,7 , and 5 ) cfu in dilution (10-1 , 10-2 , 10-3 , 10-4 and 10-5) , When taking a concentration 10 % NaCl , no bacterial growth was observed in all treatments .the findings of the current study concluded that treatment with a temperature (4ᵒC, 7ᵒC, 46ᵒC, 53ᵒC and 72ᵒC) was efficient to kill E.coli O157:H7 bacterial cells in milk , while adopting a concentration of ( 10% NaCl) was adequate to destroy all living cells of E.coli O157:H7 .

Keywords

E. coli O157:H7, temperature, salt concentration, cow and buffalo.