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International Journal of Zoology and Applied Biosciences Research Article
Bacterial diversity mapping in milk products through phenotypic and molecular identification
Athirayan S, Gokul C N, Lavanya R, Senthilkumar G P and Nazreen B
Year : 2025 | Pages: 410-414
Received on: 25/09/2025
Revised on: 17/10/2025
Accepted on: 22/11/2025
Published on: 01/12/2025
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Athirayan S, Gokul C N, Lavanya R, Senthilkumar G P and Nazreen B ( 2025).
Bacterial diversity mapping in milk products through phenotypic and molecular identification
. International Journal of Zoology and Applied Biosciences, 10( 6), 410-414.
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Abstract
Milk and dairy products serve as nutrient-rich substrates that support diverse microbial populations, including beneficial lactic acid bacteria and potentially harmful contaminants. Understanding the bacterial diversity present in dairy foods is crucial for quality control, public health, and shelf-life management. This study investigates six commonly consumed milk-derived products—raw milk, pasteurized milk, curd, paneer, buttermilk, and ice cream using combined phenotypic, biochemical, and molecular techniques. Culture-dependent methods were employed to isolate bacteria on nutrient-rich and selective media, followed by Gram staining, colony morphology, and biochemical identification. Genomic DNA was extracted from representative isolates, and 16S rRNA gene amplification was performed using universal primers (27F/1492R). PCR products were sequenced, and resulting chromatograms were analyzed using BLAST for species-level identification. The results revealed a wide bacterial diversity: raw milk carried pathogenic Staphylococcus aureus, E. coli, and Bacillus subtilis; pasteurized milk harbored spore-forming Bacillus spp.; curd and buttermilk were dominated by Lactobacillus, Streptococcus thermophilus, and Leuconostoc; paneer contained Enterobacter, Klebsiella, and Staphylococcus strains; and ice cream showed the presence of Pseudomonas, Listeria innocua, and psychrotrophic Bacillus species. Sequencing confirmed 98–100% similarity with known bacterial strains. Diversity indices demonstrated significant variation among products, with fermented products showing the highest beneficial LAB populations. This study emphasizes the importance of combined phenotypic and molecular identification for accurate microbial profiling and highlights the need for improved hygiene and processing protocols in dairy production
Keywords
Milk products, Bacterial diversity, 16S rRNA sequencing, Phenotypic identification, Dairy microbiology.
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© The Author(s) 2025. This article is published by International Journal of Zoology and Applied Biosciences under the terms of the Creative Commons Attribution 4.0 International License (creativecommons.org), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
