Bacterial Community Profile of Bovine Mastitis Infected Dairy Cow Milk by 16S rRNA Amplicon Sequencing

The prevalence of Bovine mastitis, an important disease of cow, causing huge economic loss in dairy industries, was tested in cows and other types of breeds reared at Salem and Trichirappalli district. It was interesting to note that the country breed cow was free from disease. The presence of mastitis microbes was identified by culture dependent method. Staphylococcus aureus, Staphylococcus agalactiae, Klebsiella sp. and Pseudomonas sp. were the most common bacteria found in mastitis-infected milk. Opportunistic anaerobic bacteria such as Fusobacterium necrophorum and Porphyromonas levii were found in abundance in mastitis milk samples, but not in non-mastitis milk samples. Milk samples from a mastitis-infected Jersey cow and healthy cow as a control cow were utilized to construct V3-V4 sections of 16S rRNA gene profiles, which were compared to bacterial diversity and abundance. A total of 16,000 sequence numbers were acquired from the 16S rRNA dataset, with a cumulative length of base pairs (bp) of 250. About 321 OTUs were created from these readings. Among these, 190 OTUs are similar in milk from both uninfected healthy and infected Jersey cow. A total of 70 OTUs and 61 OTUs were unique to milk obtained from healthy milk and mastitis infected milk respectively. The hierarchically clustered heat map depicted the overall perspective of the found relationships of bacterial populations among milk samples. The relative abundance of the Ochrobactrum, Pseudomonas and Stenotrophomonas (Kamilari) were associated in the milk. The Shannon index of a healthy cow milk sample was greater (4.136), suggesting the quantity and evenness of the microbial species present. The Simpson index also revealed that during a cow infection, the species richness and evenness declined. Metagenomic analysis can help us better understanding the pathophysiology of bovine mastitis, and it has the potential to be employed as a diagnostic tool as well.

The online version contains supplementary material available at 10.1007/s12088-024-01310-w.