Heat resistance and presence of genes encoding staphylococcal enterotoxins (SES) evaluated by multiplex-PCR of S. aureus isolated from pasteurized camel
AL-Dagal, Hany M. Yehia ; Elsayed Ismail ; Zeinab K. Hassan ; Abdulrahman Al-masoud ; Mosffer . 2019
Milk pasteurization eliminates vegetative pathogenic microorganisms and reduces microorganisms associated with spoilage. Camel milk is a well-accepted, traditionally consumed food in Arab countries. This study aimed to investigate the microflora of pasteurized camel milk sold in Riyadh City, Saudi Arabia. The heat resistance of the microflora was tested in culture medium and lab-sterilized milk, and its composition was verified by multiplex polymerase chain reaction (PCR) using specific primers. Further verification was performed by using separate specific primers. The identified strain survived heat treatment at 65 {degree sign}C, 72 {degree sign}C, 80 {degree sign}C, 85 {degree sign}C, and 90 {degree sign}C for 30, 15, 10, 5, and 2 min, respectively. An unanticipated result was obtained when an enterotoxin producing strain of Staphylococcus aureus showed abnormal resistance to heat treatment. The enterotoxin gene within the PCR fragment was identified as enterotoxin C by DNA sequencing. During BLAST analysis, the isolated enterotoxin C genes showed > 99% similarity to published database sequences of the Staphylococcus aureus strain SAI48 staphylococcal enterotoxin C variant v4 (sec) gene. The D-value at 90 {degree sign}C (D90) was determined after 10 sec. This is the first to report this abnormally heat resistant and enterotoxin-producing strain of Staphylococcus aureus.The use of ultra-high temperatures (UHTs) is preferable for reducing or killing bacteria in camel milk, especially if this problem is encountered in many camel milk factories.
Milk pasteurization eliminates vegetative pathogenic microorganisms and reduces microorganisms associated with spoilage. Camel milk is a well-accepted, traditionally consumed food in Arab…
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