Elsayed Elsayed Ali Ismail
Dept. Head
Heat resistance and presence of genes encoding staphylococcal enterotoxins evaluated by multiplex-PCR of Staphylococcus aureus isolated from pasteurized camel milk
Bioscience Reports • 2019
Publication Information
Authors
Hany M. YehiaCorresponding Author
ORCID logo
; Elsayed A. Ismail; Zeinab K. Hassan; Abdulrahman H. Al-masoud; Mosffer M. Al-Dagal
Keywords
D-value; Staphylococcus aureus; enterotoxin C; heat resistant; pasteurized camel milk.
Journal
Bioscience Reports
Publisher
Portland Press
Volume
39
Issue
11
Pages
BSR20191225
publication.type
International
Paper Link
Open Link
Supplementary Materials
Not Available
Abstract
Milk pasteurization eliminates vegetative pathogenic microorganisms and reduces microorganisms associated with spoilage. Camel milk is a well-accepted, traditionally consumed food in Arab countries. The present 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, 72, 80, 85, and 90°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 Basic Local Alignment Search Tool (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 decimal reduction value (D-value) at 90°C (D90) was determined after 10 s. This is the first time 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.
