Studies on prevalence of spore-forming and non-spore forming bacteria from milk samples

Microbiology

Milk serves as a complete nutritional source for human consumption, yet its high water content and neutral pH make it a prime environment for microbial proliferation. Contamination typically originates from the animal's udder, unhygienic handling, or substandard equipment. While pasteurization aims to ensure safety, the persistence of certain bacterial strains remains a significant public health concern. This study investigated the microbial quality of milk by analyzing 20 samples (10 pasteurized and 10 unpasteurized) collected from various locations in Akola city. A total of 51 bacterial isolates were recovered under aerobic and anaerobic conditions. Under aerobic conditions, 30 bacteria were isolated. Of these, 69% (20) were non-spore formers—predominantly found in unpasteurized milk (18) compared to pasteurized milk (2). The remaining 31% (10) were facultative anaerobic spore formers. Identification revealed that Escherichia coli had the highest prevalence (26.67%), followed by Staphylococcus aureus (20%), Salmonella spp. (10%), Pseudomonas aeruginosa (6.67%), and Shigela spp. (3.34%). Among aerobic spore formers, Bacillus subtilis (20%) and Bacillus cereus (13.34%) were the most common. Under anaerobic conditions, 21 bacteria were isolated. In contrast to aerobic results, spore-forming bacteria showed a significantly higher prevalence at 76% (16), while non-spore formers accounted for only 24% (5). The most prevalent anaerobic spore former was Clostridium perfringens (33.34%), followed by Clostridium titani (28.58%), Bacillus licheniformis (9.53%), and Clostridium sporogenes (4.77%). Anaerobic non-spore formers included Lactobacillus spp. (14.29%) and Escherichia coli (9.52%).The findings highlight a diverse bacterial load in both milk types, with a notably higher concentration of pathogens in unpasteurized samples and a dominance of Clostridium and Bacillus species among spore-forming isolates.

This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.