Isolation, molecular characterization and antibiogram of Lactic acid bacteria from dairy cattle sources of Mizoram, India

A total of 250 samples of dairy cattle sources comprised of 100 cattle faeces, 75 raw milk, and 75 fermented milk samples which were randomly collected from different areas of Aizawl district of Mizoram that have been analyzed bacteriologically for enumeration and isolation of Lactic acid bacteria (LAB). The 90 phenotypically positive LAB isolates were further analyzed molecularly by 16S-rRNA gene analysis and 42 isolates were found positive. A total of 20 PCR positive LAB isolates were randomly selected and sequenced, out of which 11 isolates were positive for LAB after sequence analysis, belonging to six species of LAB, namely Lactibantibacillus plantarum (4), Lactobacillus fermentum (2), Lactobacillus brevis (2), Bacillus coagulance (1), Enterococcus faecium (1) and Weissella cibaria (1). The phylogenetic tree was constructed to check the relatedness of the strains with other referral LAB strains from NCBI gene bank. These 11 isolates were further analyzed for antibiogram. All 11 LAB strains tested for antibiotic sensitivity were 100% resistant to kanamycin, whereas intermediate resistance was shown by Lactobacillus brevis FM046 to clindamycin and three strains namely Lactobacillus fermentum FM011, Bacillus coagulans FM033 and Lactobacillus brevis FM046 to penicillin. All the 11 LAB strains were 100% sensitive to most of the tested antibiotics namely amikacin, ampicillin, azithromycin, cefoxitin, cefpodoxime, ceftriaxone, erythromycin, gentamicin and rifampicin. The LAB strains detected from the dairy cattle sources of Mizoram with sensitive antibiogram might be further studied for their probiotic potential.