​Identification of Lactic Acid Bactria in Dairy Products using Culture-independent Methods: A Review

Abstract

The microbiota of dairy products is composed of starter and non-starter lactic acid bacteria, as well as other bacteria, yeasts and filamentous fungi that form secondary microbiota and play an important role in cheese ripening. The use of combined LAB strains based on compatibility and/or coexistence tests plays an important role in food production and preservation, while combinations of strains that exhibit mutually inhibitory properties must be avoided. For centuries, researchers have focused on the exploration of autochthonous LAB biodiversity from various ecological dairy niches in order to address its role in texture and flavour formation and to select strains for use as starter cultures. Recent advanced technological tools like next-generation sequencing machines have played a significant role in the fast and accurate characterization and isolation of microbial communities from dairy products. However, the characterization and isolation of LAB using culture-independent methods is also a reliable and cost-effective method for studying a bacterial community without prior cultivation. These methods include single-strand conformation polymorphism (SSCP-PCR), denaturing gradient gel electrophoresis (DGGE), thermal gradient gel electrophoresis (TGGE), real-time PCR (qPCR), terminal restriction fragment length polymorphism (T-RFLP), length heterogeneity PCR (LH-PCR), automated ribosomal intergenic spacer analysis (ARISA), and fluorescence in situ hybridization (FISH). Therefore the goal of this review is to compare and describe the most recent culture-independent molecular-based methods for the characterization and isolation of LAB in dairy products.