In –Vitro Assessment of Probiotic Attributes of Propionibacterium freudenreichii Isolated from Dairy Cheese

Abstract

Dairy propionibacteria possess innumerable advantages as probiotics, in food preservation and vitamin production. Propionibacterium freudenreichii is one among them and is known to produce cyanocobalamine (Vitamin B12) in stable quantities. Deficiency of Vitamin B12 is a major health issue among vegetarians and vegans making it a global concern.  Hence, an attempt has been made to isolate Propionibacterium from dairy products. Propionibacterium isolates were enumerated by employing standard dilution plate count technique using yeast extract lactone agar (YELA). Gram’s reaction, pigmentation, catalase test, endospore production, nitrate reduction, gas production, fermentation of sucrose and maltose were performed to eliminate non-propionibacteria during isolation. Isolates that tested Gram positive, pigmented, catalase positive, non-endospore formation and could ferment sucrose as well as maltose were further used for identification by 16S rRNA sequencing. One isolate was confirmed to be Propionibacterium freudenreichii (PF) as identified by 16s rRNA gene amplification and Sanger’s sequencing. The confirmed isolate was subjected to various tests to check for its probiotic attributes. Haemolysis activity was tested to ensure non-pathogenicity using blood agar medium and isolate was found to be non-pathogenic. Antibiotic susceptibility pattern of the isolate was studied using currently prescribed seven antibiotics representing activity against both Gram-positive and Gram-negative bacteria. The isolate was found sensitive for all the seven antibiotics tested. The isolate was able to tolerate the pH till 2 and sustain by exhibiting minimal growth at 2.0 g L-1 of bile salts. Results reveal that PF, isolated native culture from cheese, proved to possess attributes for probiotic agent under in -vitro conditions.