Artisanal buffalo milk curd from Charfassion upazila of Bholadistrict in Bangladesh as a potent source of bifidobacteria

The present study explored the traditionally prepared fermented buffalo milk curd to isolate and characterize Bifidobacterium sp. towards developing future probiotics. Standard methods have been applied to identify Bifidobacterium sp. using bifidobacteria selective media, bifidobacteria specific mupirocin resistance test, phosphoketolase activity and commercial biochemical kit. The strains further confirmed by xfp gene PCR amplification. The growth dynamics of the identified isolates was also determined by monitoring the turbidity of the cultured media spectrophotometrically. A total of 20 isolates obtained from selective media were found gram positive, catalase negative, rod or v-shaped, non-motile and identified as presumptive bifidobacteria. All the isolates were resistant (zone diameter <10 mm) to the antibiotic mupirocin. However, the phosphoketolase activity of the isolates were varied significantly (p<0.05). A high, moderate and weak/no phosphoketolase activity was exhibited by 35%, 20% and 45% isolates, respectively. In the contrary, fourteen isolates (70%) amplified well with phosphoketolase activity encoded xfp gene and produced a PCR product of 704 bp. Combining the findings of these three tests, only six isolates (30%) displayed mupirocin resistance, high phosphoketolase activity and amplification with xfp gene. Of these six isolates biochemical test confirmed three isolates as Bifidobacterium mongoliense and two as Bifidobacterium pseudolongum subsp. globosum. The exponential phase growth rate of the six isolates also varied significantly (p<0.05) and ranged from 0.16±0.01/h to 0.34±0.02/h. Traditionally prepared buffalo milk curd from Charfassion upazila of Bhola district, Bangladesh could be a potent source of Bifidobacterium sp. However, species-specific identification and elucidation of probiotic potential are pivotal for future industrial use.