Abstract:

Lantibiotics, which are peptide antibiotics that undergo post-translational modifications, are gaining increasing significance due to their powerful antibacterial properties, which have the potential to mitigate the rising worldwide issue of antibiotic resistance. Earlier, it had been reported that jute endophytic bacteria, Staphylococcus hominis MBL_AB63, can produce a class I lantibiotic called ‘homicorcin’. The investigation of the whole genome sequence of S. hominis MBL_AB63 unveiled the biosynthetic gene cluster consisting of six genes and two transporter genes responsible for biosynthesis and extracellular trafficking, respectively. Production and purification of homicorcin demand great attention for its application in therapeutic purposes. Nevertheless, the production of the lantibiotic by its producing strain is hindered by factors such as limited secretion and a certain degree of pathogenicity. Therefore, this study's objective is heterologous homicorcin expression in another Gram-positive strain Lactococcus lactis NZ9000, generally regarded as safe (GRAS) by FDA. The molecular cloning process commenced by targeting the immunity gene (homI) within pMG36c, a well-maintained expression vector specifically designed for Gram-positive bacteria. The wild-type host strain, susceptible to homocorcin, exhibited immunity to the lantibiotic when it was genetically modified with homI. The six genes fragment and transporter genes fragment have been ligated together in a tandem manner and verified by colony PCR. The subsequent step involves the transformation of the construct in the host strain and the evaluation of its expression efficiency. The study also aims to conduct site-directed mutagenesis of the structural gene to investigate the impact on the expression level and activity of the lantibiotic.