[Differentiation of bacilli isolated from raw and pasteurized milk]

Area of Science:

• Microbiology
• Food Science

Background:

• Aerobic spore-forming microorganisms, particularly Bacillus species, are frequently found in milk.
• Understanding their species composition and biochemical properties is crucial for assessing milk quality and safety.

Purpose of the Study:

• To determine the species composition of Bacillus strains isolated from fresh and pasteurized milk.
• To characterize the biochemical properties of these Bacillus strains.
• To assess the implications of these findings for milk hygiene and quality.

Main Methods:

• Isolation and differentiation of 190 aerobic spore-forming Bacillus strains from milk samples.
• Classification of strains using Petrova's diagram.
• Evaluation of morphological, biochemical, and cultural characteristics.

Main Results:

• The dominant species identified was Bacillus licheniformis (55.9%), followed by Bacillus subtilis (24.8%), Bacillus pumilus (14.7%), and Bacillus cereus (4.6%).
• All studied strains belonged to morphological group I, consistent with Petrova's diagram.
• Isolated Bacillus strains demonstrated significant biochemical activity, particularly in protein and carbohydrate metabolism.

Conclusions:

• The species composition of Bacillus in the studied milk samples is characterized by a predominance of Bacillus licheniformis.
• The biochemical activity of these Bacillus strains is high, indicating their potential impact on milk spoilage and quality.
• These findings underscore the importance of monitoring Bacillus populations for ensuring the hygienic quality of dairy products.