Establishment Of Rapid Detection For Lactic Acid Bacteria

The lactic acid bacteria(LAB) can convert the lactose into lactic acid. Most of them were used as starter cultures in the manufacturing processes of various fermented foods,beverages,and feed products. Because of their peculiar metabolic and technological properties,we need to control the salty and quality in LAB fermented foods production. Rapid and reliable detection of LAB is of great interest for basic knowledge and also for industrial purposes.In this paper,polyphasic taxonomy identification of 5 milk derived lactic acid bacillus strains(1Lactobacillus plantarum,1Lactobacillus casei, 1Lactobacillus delbrueckii subsp.bulgaricus, 1Lactococcus lactis subsp.cremoris, 1Streptococcus thermophilus) were studied. We designed primers and probes specific to conduct the TaqManTM real-time PCR assays,including specific testing,sensitivity testing and detection of LAB in the LAB beverages.At same time,application of PCR-DHPLC to indentify LAB,we optimized conditions of PCR and DHPLC. The result indicates that specific of real-time PCR is good,and the minimum detection limit could reach 24cfu/mL.The following optimum running conditons in PCR-DHPLC system were used:column temperature of 61℃;and an analytical gradient buffer B of 46% for 0 min,52% for 0.5 min,61% for 5.5min at a flow rate of 0.9mL/min. Application of real-time PCR to detect and indentify LAB is more rapid,more sensitive and more specific than conventional culture method.And PCR-DHPLC is repeatable, high automated,which could detect five LAB at once. And PCR-DHPLC is a fast,accurate and reliable detection of lactic acid bacteria. Both of the two detection techniques could be applied to the identification of LAB.