Characterization and Molecular Identification of Bacteria Isolated from Raw Camel’s Milk in Al-Ahsa, Saudi Arabia

Abstract

Background: Camel’s milk has many benefits on human health, however, drinking fresh untreated camel’s milk may pose a serious health concern. Therefore, the current study aimed to determine the bacteriological quality of raw camel’s milk by isolating, characterizing and identifying bacterial strains from the untreated milk in Al-Ahsa region, Saudi Arabia. Methods: Three raw milk samples were collected under aseptic conditions and bacterial counts were determined using the serial dilution plate method. Discrete colonies were picked based on morphological differences. Five representative bacterial strains were characterized by phenotypic analysis, biochemical tests using the API 20E system and sequencing of 16S rRNA genes. Result: The results showed that the total bacterial counts in camel’s milk reached 3 × 107 CFU mL-1, which exceeds the limit specified by the Saudi Food and Drug Authority. The isolates formed colonies that were rounded, entire, convex and elevated from the surface of the agar. The diameter of the colonies ranged from 1 to 4 mm after a 48-h incubation at 30°C on the M17 medium. The isolates were able to metabolize 12 (60%) to 15 (75%) out of 20 different compounds as growth substrates present in the API 20E test system. Additionally, BLAST analysis of the 16S rRNA sequences of the five bacterial isolates revealed that they were closely related to various known bacterial genera (e.g., Bacillus, Kocuria and Pseudomonas), indicating the diverse composition of the microflora in raw camel’s milk. Unlike the other four bacterial isolates, a clear zone was noted around the growing one bacterial isolate, CMK1, highlighting a remarkable degradation of the hemoglobin in the erythrocytes, highlighting the potential existence virulence determinants. Good hygiene practices during milk production and handling are recommended to ensure high raw milk quality and avoid health risks. This study sheds light on the bacterial diversity of raw camel’s milk that has a direct impact on public health and the economy.