In vitro probiotic characterization of Lactobacillus casei isolated from marine samples

• First report of marine Lactobacillus casei isolates from Indian subcontinent.
• High gastrointestinal survival in contrast to Lactobacillus casei Shirota, starter culture in a commercial dairy drink.
• Attributes of growth and survival at low pH and high bile salt concentrations.
• Bacteriocins remarkably stable to freezing and autoclaving and exhibited biomedical potentials.
• EPS produced by the marine isolate possessed heavy metal remediation potential and antiadhesive activity.

The present study evaluated probiotic potentials of marine bacteriocinogenic lactic acid bacteria (LAB). Three marine LAB isolates, designated SB71, SB73 and SB93, were characterized as Lactobacillus casei. They possessed features like high level of gastrointestinal survival, inability to form biogenic amines, adherence to Caco-2 cells and marked cholesterol assimilation. To the best of our knowledge, this is the first report about marine probiotic bacteria from the Indian subcontinent. Tolerance of the three isolates to NaCl, bile and low pH was noteworthy. EPS from SB93 markedly disrupted bacterial adherence and promoted remediation of cadmium and lead. Broad-spectrum antimicrobial and antiadhesive activities were exhibited by the SB93 bacteriocin and the active principle survived autoclaving. All three bacteriocins exhibited antimicrobial activity against Vibrio cholerae as opposed to previous results. Earlier reports mentioned that the bacteriocinogenic isolates were cultivated for 24 h following which antimicrobial action of bacteriocins (in cell-free culture supernatants) was noted. However, in the present study, the test LAB isolates were cultivated for a period of up to 5 days and bacteriocins (in cell-free supernatants collected daily from the cultures) continued to exhibit antimicrobial activity, thus advocating for their potential lasting effect in diseased individuals.