Doaa Mahmood Mahdy - Department of Biology, College of Science, Mustansiriyah University, Baghdad, Iraq
Nibras Nazar Mahmood - Department of Biology, College of Science, Mustansiriyah University, Baghdad, Iraq
Wala’a Shawkat Ali - Department of Biology, College of Science, University of Baghdad, Baghdad, Iraq

Background and Aim: Lactobacilli are known for their probiotic activities and potential to combat pathogens. This study aimed to investigate the antimicrobial activity of Lactobacillus strains isolated from various sources against pathogenic bacteria, with the objective of identifying potential bacteriocin producers. Materials and Methods: A total of ۱۴۰ samples were collected from different sources. Samples were cultured on selective media such as MRS and SL agar for isolation of Lactobacillus spp under anaerobic conditions. The suspected bacteria appeared Gram positive, diploid bacilli or coccobacilli. The isolates were subjected to various biochemical tests such as catalase, oxidase, also hydrolysis test was done by growing on MRS containing ۱% calcium carbonate. The antimicrobial activity of bacteriocin was screened by using three method including (Agar-plug diffusion method, Filter paper disc method and agar-wells diffusion method). Molecular identification of the best bacteriocin producer was achieved using ۱۶S rRNA sequencing. Results: The study found that L. helveticus DF isolated from feces exhibited the highest bacteriocin production efficiency. Concentrated bacteriocin from L. helveticus DF demonstrated potent antibacterial activity against multi-drug resistant bacteria, with ۸۰ AU/ml against Pseudomonas aeruginosa and ۴۰ AU/ml against Enterococcus faecalis. Conclusion: The study highlights the potential of Lactobacillus bacteriocins as effective antibacterial agents, offering a promising alternative to combat antibiotic resistance. Further research is warranted to elucidate the mechanisms and assess the safety and efficacy of bacteriocins for their use as bio-therapeutic agents.

Lactobacillus Species, Antibacterial Activity, Bacteriocin, Multi-drug Resistance Bacteria, گونه لاکتوباسیلوس, فعالیت ضد باکتریایی, باکتریوسین, باکتری های مقاوم به چند دار