Adikari A M M U, Priyashantha Hasitha, Disanayaka J N K, Jayatileka D V, Kodithuwakku S P, Jayatilake J A M S, Vidanarachchi J K
Department of Food Science and Technology, Wayamba University of Sri Lanka, Kuliyapitiya, Sri Lanka.
Department of Molecular Sciences, Swedish University of Agricultural Sciences, Box 7015, SE-750 07 Uppsala, Sweden.
Heliyon. 2021 Oct 6;7(10):e08136. doi: 10.1016/j.heliyon.2021.e08136. eCollection 2021 Oct.
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.
传统发酵水牛奶凝胶是斯里兰卡一种受欢迎的源自水牛奶的产品。主要采用回接（添加少量先前的发酵物）技术生产，遵循乡村层面传承已久的传统工艺。因此，在不同的生产地理区域可能会形成多样且未分类的发酵剂培养物。在本研究中，我们旨在阐明来自斯里兰卡主要生产地区（n = 22）的乳酸菌（LAB）的多样性及其特性，包括益生菌特性。从当地生产的样品（n = 23）中分离出乳酸菌，并根据形态、生化、生理特征以及益生菌特性潜力进行表征。分离株呈现出五种不同的菌落和细胞形态，基于利用葡萄糖产生二氧化碳的情况被分类为异型发酵菌、同型发酵菌和兼性异型发酵菌。没有分离株显示在5°C或0°C下生长的能力，而分别在15°C和45°C下观察到71%和100%的分离株存活。扩增核糖体DNA限制性分析（ARDRA）主要根据其DNA条带模式将分离株分为三个不同的簇。随后，分离株的16S rRNA测序揭示存在四种物种，即（n = 18）、（n = 2）、（n = 2）和（n = 1），并且在系统发育分析中，由四个不同的进化枝代表。所有分离出的物种都表现出具有抗生素敏感性、抗菌特性、胆汁酸耐受性和酸耐受性的良好益生菌潜力。总之，斯里兰卡传统的回接工艺含有多样的乳酸菌，在物种水平上地理差异可忽略不计。我们的工作为水牛乳发酵起始培养物开发的未来应用提供了坚实的基础和见解。
