Isolation and identification of Lactobacillus spp. from raw milk and determination of their acid producing ability

Economic benefits of lactic acid bacteria have encouraged microbiologist to identify local bacteria for industrial use. In this study Lactobacillus spp. were isolated from raw milk that had been collected from two domestic milk collection centers, Sarab and Ardebil, Iran. These isolates were characterized by phenotypic methods and their ability to reduce pH as a technological property was determined. Six out of 14 isolates were identified as Lactobacillus spp. based on biochemical and physiological characterization. The following species were identified: Lactobacillus plantarum, L. acidophilus, L. curvatus, L. casei and L. berevis from Ardabil raw milk collection center and Lactobacillus plantarum and Lactobacillus berevis from Sarab milk collection center. Statistical analysis of pH reduction of MRS broth by 6 isolates revealed that there is no significant difference between the isolate's ability during 4 to 48 hours incubation. we conclude that these native species are suitable alternatives for industrial starter cultures.