Isolation, identification and characterization of species diversity from : traditional fermented buffalo milk gels in Sri Lanka.

Traditional fermented buffalo milk gel; , is a popular buffalo milk-derived product in Sri Lanka. Predominantly, it is produced using the back-slopping (adding a small amount of the previous fermentate) technique, following the life-long traditions available at the cottage level. Hence, diverse and unclassified starter cultures are likely to be established across the varying geographical regions of production. In the present study, we aimed to elucidate the diversity of lactic acid bacteria (LAB) and their characteristics including probiotic properties from major production areas (n = 22) in Sri Lanka. Lactic acid bacteria was isolated from locally produced samples (n = 23) and characterized based on morphological, biochemical, physiological profiles and potential of probiotic properties. The isolates revealed five different colony and cell morphologies and were classified as heterofermenters, homofermenters and facultative heterofermenters based on CO production using glucose. None of the isolates showed the ability to grow either at 5 °C or 0 °C, while 71 % and 100 % survival of the isolates were observed at 15 °C and 45 °C, respectively. Amplified ribosomal DNA restriction analysis (ARDRA) primarily grouped the isolates into three distinct clusters based on their DNA banding patterns. Subsequently, 16S rRNA sequencing of isolates revealed the presence of four species namely, (n = 18), (n = 2), (n = 2) and (n = 1) and in the phylogenetic analysis, it was represented by four distinctive clades. All the isolated species demonstrated promising probiotic potential with antibiotic sensitivity, antimicrobial properties, bile acid tolerance and acid tolerance. In conclusion, traditional back-slopping in Sri Lanka contains diverse LAB, with a negligible geographical variation at species-level. Our work provides a strong foundation and insights into future applications in starter culture development for the fermentation of buffalo's milk.