Consiglio per la Ricerca e la Sperimentazione in Agricoltura, Centro di Ricerca per le Produzioni Foraggere e Lattiero-Casearie (CRA-FLC), Lodi, Italy.
Lett Appl Microbiol. 2014 Sep;59(3):299-305. doi: 10.1111/lam.12275. Epub 2014 May 8.
The diversity of lactic acid bacteria (LAB) species in donkey's milk was analysed by culture-dependent microbial techniques. Dominant strains were isolated on agar media generally used for enumerating LAB. To enrich the number of acidifying LAB present, the milk samples were incubated at 37°C for 24 h (cultured milk samples, CM). One of the CM samples was heat-treated at 63°C for 10 min before incubation at 37°C (heat-treated and cultured milk sample, TCM) to select thermophilic LAB. The microflora in these CM and TCM samples was then compared to that of the raw milk samples (RM). Among the 129 LAB isolates, 10 different species (four Enterococcus, five Streptococcus and one Pediococcus) were identified by molecular methods. Although the 10 LAB species were present in the RM samples, only three and two isolates were found in CM and TCM samples, respectively. Despite the selection protocol being set up to favour the isolation of all LAB isolates present in donkey milk, relatively few species and biotypes were isolated. No LAB isolates belonging to the most technologically important dairy starter species were detected. The possible factors related to the limited LAB diversity in donkey's milk have been discussed below.
There is increased interest in using donkey's milk as a source of human nutrition. The large amounts of antimicrobial components and defence factors present in donkey's milk provide protection from microbial infections and distinguish donkey's milk from the milks of other mammals. However, the microbiota in donkey's milk has so far been poorly characterized, specifically with regard to the lactic acid bacteria (LAB). This study has identified cultivable, acidifying and thermoduric LAB that could be used to develop starter cultures. This is the first study to investigate the culturable LAB microbiota present in donkey's milk.
通过依赖培养的微生物技术分析了驴奶中乳酸菌（LAB）的多样性。在通常用于计数 LAB 的琼脂培养基上分离出优势菌株。为了富集存在的酸化 LAB 的数量，将牛奶样品在 37°C 下孵育 24 小时（培养的牛奶样品，CM）。在 37°C 孵育之前，将其中一个 CM 样品在 63°C 下热处理 10 分钟（热处理和培养的牛奶样品，TCM）以选择嗜热 LAB。然后将这些 CM 和 TCM 样品中的微生物群与原始牛奶样品（RM）进行比较。在 129 个 LAB 分离株中，通过分子方法鉴定了 10 个不同的种（四个肠球菌、五个链球菌和一个乳球菌）。尽管 RM 样品中存在 10 种 LAB 种，但仅在 CM 和 TCM 样品中分别发现了 3 种和 2 种分离株。尽管选择方案旨在有利于分离驴奶中存在的所有 LAB 分离株，但分离的种和生物型相对较少。未检测到属于最具技术重要性的乳制品起始物种的 LAB 分离株。下文讨论了与驴奶中有限的 LAB 多样性相关的可能因素。
人们对使用驴奶作为人类营养来源的兴趣日益增加。驴奶中存在大量的抗菌成分和防御因子，为抵御微生物感染提供了保护，使驴奶有别于其他哺乳动物的奶。然而，到目前为止，驴奶中的微生物群，特别是乳酸菌（LAB），还没有得到很好的描述。本研究鉴定了可用于开发起始培养物的可培养、酸化和耐热 LAB。这是第一项研究驴奶中可培养 LAB 微生物群的研究。
