Colicin production, antibacterial effect and molecular sequencing of Escherichia coli isolated form different sources

Bacteria especially Escherichia coli (E. coli) possess several mechanisms enabling them to respond to changing environment and to out compete other bacteria. E. coli strains are known to produce bacteriocins, one of which is colicin. Colicins are effective against closely related enterobacteriaceae and are considered viable alternatives to antibiotics. In this study Twelve (12) E. coli strains were isolated from food, water soil and anal swab. They were characterized, confirmed and identified as E. coli. The isolates were subjected to stress condition to stimulate colicin production. The colicin produced was tested against three indicator organisms namely Salmonella Sp, Klebsiella Sp and Staphylococcus aureus. Comparative antibiotic susceptibility test against standard antibiotics and the colicin produced was carried out to ascertain the efficacy of the colicin. E. coli isolates were also subjected to antibiotic sensitivity test to determine the resistance profile of the colicin producing strains of E. coli. Plasmid amplification to identify colicin plasmid was also carried out to determine the relationship between colicin production and resistance to antibiotics of colicinogenic E. coli. Result obtained showed that six out of the twelve strains of E. coli isolated from water produced colicin that showed high antibacterial activity against the indicator organisms. The comparative antibiotic resistance profile revealed that the colicin had better antibacterial activities than some of the antibiotics used. Furthermore the colicinogenic E. coli also showed resistance to some of antibiotics used. The plasmid amplification showed the colicinogenic E. coli possess high molecular weight (4kb) colicin plasmid while the gene sequencing revealed the presence of ColF and ColR plasmids. The result of this work underscores the fact that the use of colicin as an alternative to standard antibiotics can be further explored, especially in the search for alternatives to antibiotics considering the high level of bacteria resistance to standard antibiotics.