Screening Enterococcus isolates for antimicrobial and in vitro antitumor activity against colorectal carcinomas

Abstract

Abstract Enterococci are a part of the natural intestinal flora of humans and animals and play an important role in keeping their microbial balance. Many species of Enterococci are also used as probiotics that produce vitamins, stimulate the immune responses, and maintain the integrity of gut. The use of dietary supplements to reinforce some gut flora components is a current aspect of functional food sciences to treat various diseases. Enterococcus also produce some enterocins that respond actively against Escherichia coli and Salmonella pullorum and inhibit their growth. The use of advanced techniques of high through put screening of microbial extracts for antimicrobial activity will be helpful for obtaining bioactive compounds. In present study, 21 strains of Enterococcus were isolated and identified morphologically and biochemically. Out of these, 9 strains showed antimicrobial activity against Psuedomonas, Enterobacter, Klebsiella, and Staphylococcus. The strains also showed sensitivity against certain antibiotics such as amoxicillin, norfloxacin, streptomycin, vancomycin, and nalidixic acid. The crude extracts of the isolates also showed antitumor activity against HCT 116 colorectal carcinoma cell line. The crude extracts of these bioactive Enterococcus strains were analyzed chemically by thin layer chromatography (TLC) and high-performance liquid chromatography (HPLC). So, the present study revealed that the antimicrobial compounds produced by these bioactive Enterococcus strains could be used against Psuedomonas, Enterobacter, Klebsiella, and Staphylococcus. Moreover, these strains could be investigated as potential probiotic agents to treat colorectal cancer because of their significant in vitro antitumor activity against colorectal carcinoma (CRC).