Cytotoxicity and antioxidant activities of bacteriocins extracted from novel marine lactic acid bacteria Lactococcus lactis NAN6399

Abstract This study aimed to evaluate the cytotoxicity, antioxidant, and antimicrobial activities of the bacteriocins produced by novel marine lactic acid bacteria, specifically Lactococcus lactis NAN6399, isolated from the Mediterranean Sea coast of Alexandria. Additionally, comprehensive sequencing, analyses, and protein identification of this bacteriocin was conducted. The results indicated that this isolate has a broad antimicrobial spectrum against the tested bacterial indicators. Bacteriocin purified from NAN6399 had a molecular weight of approximately 20 kDa and was designated as “lactococcin972”. Furthermore, cytotoxicity and antioxidant activities were conducted on bacteriocin by 3(4,5-dimethylthiazol-2-yl),2,5-diphenyl-tetrazolium bromide (MTT) assay and Diphenyl picrylhydrazyl (DPPH) method, respectively. The results showed that “lactococcin972” exhibited distinguished cytotoxic activity with inhibition rates of 80% against breast cancer (MCF-7) and 30% against lung cancer (A549). Additionally, “lactococcin972” exhibited reduction activity of 72% against DPPH. These findings suggest that lactococcin972 has significant potential as therapeutic agents due to their notable antimicrobial, cytotoxic, and antioxidant properties.