Microbial ecology of handmade dairy products - Molecular methodologies for isolation and identification

Dairy products are generally defined as foods produced from milk, the secretion of the mammary glands of mammals, usually cows (bovine), sheep, goats, buffalo, camel or yak. The production of fermented dairy foods, involves complex and dynamic microbial ecosystem in which numerous biochemical reactions occur. In these products the predominant microbiota is principally constituted by a group of bacteria, namely lactic acid bacteria (LAB), which are directly involved in the metabolic conversion of milk sugar, as source of energy, in lactic acid. LAB group plays an important role both as natural competitive microbiota and as specific starter cultures. In particular, it is well known as the complex sensory characteristics are strictly linked to the presence of some specific ecotypes of these bacteria. Nowadays, the researches in dairy microbiology are focusing on the study of the diversity and dynamics of microorganism involved in these products. Hence, the study of LAB microbiota as presence and type of microorganisms associated has been shown to be essential both for understanding their individual contributions and to better comprehend their role as part of the microbial communities of these products.Traditionally, the bacterial diversity in dairy products is based on growing of microorganisms on selective media and their following identification at genus/species level using phenotypic characterization. In the last decade, bacterial identification based on molecular methods, especially those including the sequencing of genes coding the 16S ribosomial RNA (rRNA) gene, has become a very important tool to study the microbiota in different dairy environments.