Evaluation of different lactic acid bacterial strains for probiotic characteristics

Abstract

Objective: The objective of the present study was to collect different Lactic acid bacterial strains from culture collection centers and screen their functional probiotic characteristics such as acid tolerance, bile tolerance, antibacterial activity and antibiotic sensitivity for their commercial use.

Materials and Methods: Acid and bile tolerence of selected LAB(Lactic acid bacteria) was determined. The antibiotic resistance of Lactobacillus species was assessed using different antibiotic discs on de Mann Rogosa Sharpe broth (MRS) agar plates seeded with the test probiotic organism. The antibacterial activity of LAB was assessed by using well diffusion method.

Results: Among the six probiotic strains tested, all showed good survivability at high bile salt concentration (0.3 to 2.0 % oxgall) and good growth at a low pH of 1.5 to 3.5. These probiotic species showed good survival abilities in acidic pH of 2.0 to 3.5 except Lactobacillus delbrueckii subspp. bulgaricus 281 which did not grown at pH of 2.0. Lactobacillus fermentum 141 was able to grow even at pH of 1.5 also. Among the six lactic acid species, Lactobacillus fermentum 141 (except Tetracycline), Lactobacillus delbrueckii subspp. Bulgaricus 281 except (Cefpodoxime) and all other LAB were resistant to all the antibiotics tested (Ampicillin, Nalidixic acid , Ciprofloxacin ,Co-Trimoxazole, Gentamicin and Cefpodoxime). All these probiotic organisms were screened for their in vitro inhibition ability against pathogenic microorganisms namely, E.coli ATCC (American type culture collection centre), Pseudomonas aeruginosa, Salmonella paratyphi, Staphylococcus aureus. Lactobacillus delbrueckii subspp. bulgaricus 281, Lactobacillus casei 297 and Lactobacillus fermentum 141 inhibited the growth of all the pathogenic bacteria used in the study.

Conclusion: The study indicated Lactobacillus fermentum 141 and Lactobacillus casei 297 as potential functional probiotics for future in vivo studies for commercialization in the food industry.