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Antimicrobial Activities of Conducting Polymers and Their Derivatives
Published in Ram K. Gupta, Conducting Polymers, 2022
Palanichamy Nandhini, Mariappan Rajan
The peptidoglycans present in the bacterial cell wall provide mechanical support to maintain the morphology. The cationic polymer targets the lipid II, which is an indispensable pioneer for the synthesis of peptidoglycan layers to avert cell wall fabrication. It was found that daptomycin can block the cell wall fabrication by the elimination of lipid II synthesis proteins [96]. Lipid II is synthesized in the bacterial cytosol and transported by the lipid screens, undecaprenyl phosphate, and flippase. Hence, the molecules that can focus on the lipid II screens may as well restrain cell wall fabrication.
Characterization and mode of action of a potent bio-preservative from food-grade Bacillus licheniformis MCC 2016
Published in Preparative Biochemistry and Biotechnology, 2019
Nithya Vadakedath, Prakash M. Halami
Genetically engineered reporter strains of B. subtilis have been used for the rapid detection of the MOA of antibacterial compounds.[26,27,38] De Pascale et al.[38] used B. subtilis strain expressing the Enterococcus faecium vanRS and vanH–lacZ fusion genes as a reporter strain for the MOA study. In the presence of cell wall inhibitors and lysozyme, it is induced to produce β-galactosidase activity. They claimed that reporter-strain-based antibiotic discovery is a powerful tool exhibiting operational ease and specificity. In this study as well, the β-galactosidase activity of the reporter strains (BSF 2470, TMB 488, TMB 299, and TMB 279) treated with different concentrations of ppABP (0, 0.4, 2.0, 4.0, or 8.0 mg mL−1) was assayed to determine the MOA of the ppABP of MCC 2016. The reporter strains B. subtilis BSF 2470 and TMB 488 have a promoter, which is induced by cell wall acting lipid II binding antibacterial substances.[26,39] Chemical substances, such as SDS and ethanol, etc. also generally induce BSF 2470, whereas, the induction of β-galactosidase activity of TMB 488 is very specific and particularly differentiate cell wall acting antibacterial substances. While the reporter strains TMB 299 and TMB 279 are induced by lipid II binding lantibiotics (viz. nisin, subtilin, actagardine, and gallidermin) and lipid II lantibiotic bacitracin,[40] respectively. The ppABP of MCC 2016 was found to induce the reporter strains, BSF 2470, TMB 488, and TMB 299 (Fig. 6). No induction was noticed for the strain TMB 279 (Fig. 6). Maximum induction of β-gal for BSF 2470 and TMB 299 was observed at 2 mg mL−1 ppABP. In the case of TMB 488, maximum induction was noted at 8 mg mL−1 (27 Miller units) (Fig. 6). The induction of BSF 2470, TMB 488, and TMB 299 strains but not TMB 279 by the ABP of MCC 2016 indicates that it is a cell wall acting cationic l antibiotic similar to nisin or subtilin and is not bacitracin.