Suvarna, V. ChavannavarHARISH KUMAR, K.2023-01-082023-01-082022-09-05Th-13288https://krishikosh.egranth.ac.in/handle/1/5810191513The vitamin B12, cobalamin is a water soluble vitamin is needed for red blood cell synthesis and nervous system functioning. The animal based foods are the sources of cobalamin and plant foods lack cobalamin. Archaea and eubacteria are capable of cobalamin synthesis. Propionibacterium freudenreichii is the only food bacterium able to synthesize stable quantities of cobalamin. Hence, attempted to isolate Propionibacterium freudenreichii, identify using molecular methods, screening isolates for probiotic characteristics, mutants isolation, vitamin assay, auxanographic patterns, developing vitamin B12 enriched fermented food as an alternative source of vitamin B12. The isolation of dairy propionibacteria from milk, curd, cheese, pickle and silage was done using Yeast Extract Lactone Agar medium. The isolates were subjected to biochemical and molecular characterization and cheese isolate was identified as Propionibacterium freudenreichii using 16S rRNA characterization. It was exposed to UV radiations to get UV resistant mutants (PFM1-10). The auxanography, antibiotic sensitivity, haemolytic activity, vitamin B12 synthesizing ability of mutants and wild strain were studied. The wild strain could synthesize the highest vitamin B12 (15.23 μg 100 mL-1). Mushrooms were cultivated under in-vitro conditions along with vitamin B12 precursor and P. fruedenreichii and it was found that the treated mushrooms could not synthesize vitamin B12. Further, attempts were made to develop milk-based fermented beverage using starter inocula of home-made curd, Propionibacterium freudenreichii, Lactobacillus acidophilus, P. freudenreichii + L. acidophilus and yoghurt as treatments. The highest cobalamin production (10.37 μg 100 mL-1) and sensory acceptability score (8.15 of 9) was found in the treatment inoculated with Propionibacterium freudenreichii alone. The recommended dietary allowance for vitamin B12 is 2.4 μg and this can be met by consumption of 23 mL of developed milk product.EnglishThesis