Isolation, Identification and Characterization of Native Probiotic Lactobacillus Isolates From Different Curd Samples

Abstract

Probiotics are live microorganisms (usually bacteria and fungi) that are similar to beneficial microorganisms found in the human gut that are taken as dietary supplements or found in foods. Common examples are Lactobacillus, Streptococcus and Bifidobacterium. They may occur naturally in curd or yogurts and certain fermented foods. Probiotics have been used as treatment for various gastrointestinal conditions including irritable bowel syndrome and traveller’s diarrhoea. Curd is a fermented milk product, most commonly used by Indian population. Curd has large amounts of probiotic bacteria which are exceptionally good for our Gut. It is the outstanding source of protein for the vegetarians. It is also good for lactose intolerant people. In India curd is considered as a food which is very good for the stomach as it helps in digestion and gives relief from spicy food. The nutritional values of probiotic curd apart from good bacteria, It is full of vitamin B-12, vitamin B-2, vitamin B-6, iron, potassium and magnesium. A total of eight different Lactobacillus isolates were obtained from 05 curd samples and their identification on the basis of Gram staining, colony morphology and biochemical tests was done. All these 08 Lactobacillus isolates were Gram positive rod shaped bacteria showing large, round, irregular colonies greyish-white, opaquein appearance. The isolates were preserved in starter culture curd, this is the best way to preserve lactobacillus strains for atleast one and half month as it only survive for one week only on Briggs slants. All the isolates showed negative results for Catalase, Oxidase, Motility and Simmon’s citrate tests. All the isolates were positive for Lactose utilization and Milk coagulation test. These 08 isolates were tested for cud formation on the basis of certain parameters (smell, texture and taste etc.). The most preferred curd was obtained from isolate LB-5 with overall acceptability (+ 4 Score and Ist Rank) and the least preferred curd found to be one obtained from isolate LB-3 with overall acceptability (+3/4 Score and VIth Rank). The genomic DNA of one isolate was successfully isolated using modified CTAB method. These isolates may be further characterized on molecular basis and may be tested for their ability as biocontrol agent or biofertilizers.