Anti-fungal and anti-inflammatory linear lipopeptides from a marine derived bacterium Bacillus subtilis

Abstract

Marine bacteria are a potential producer of structurally diversified bioactive metabolites that are not found in terrestrial sources. In our ongoing projects to search for new antimicrobial agents from marine-derived bacteria, we isolated a bacterial strain 109GGC020 from a marine sediment sample collected from Gageocho, Republic of Korea. The strain was identified as Bacillus subtilis based on a 16s rRNA sequence analysis. After a 7 day fermentation of the strain, four new linear lipotetrapeptides (1-4), were isolated using chromatographic procedures. Their structures and stereochemistry were elucidated by 2D NMR and MS data analyses and chemical means. These compounds were found to exhibit significant antifungal activities against pathogenic fungi Rhizoctonia solani, Botrytis cinerea and Colletotrichum acutatum with MICs values of 0.02 &#8211 0.06 μM. In addition, compounds 1-4 displayed good time course motility inhibition and lytic activity against the late blight pathogen Phytophthera capsici. These compounds also showed potent antimicrobial activity against Gram positive (Bacillus subtilis and Staphylococcus aeureus) and Gram negative (Salmonella typhi and Pseudomonas aeruginosa) bacteria with MICs values of 0.04 &#8211 0.08 μM. Furthermore, to investigate the anti-inflammatory effects of the new peptides in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells, the expression of mRNA and protein using RT-PCR bacterial strain 109GGC020 from a marine sediment sample collected from Gageocho, Republic of Korea. The strain was identified as Bacillus subtilis based on a 16s rRNA sequence analysis. After a 7 day fermentation of the strain, four new linear lipotetrapeptides (1-4), were isolated using chromatographic procedures. Their structures and stereochemistry were elucidated by 2D NMR and MS data analyses and chemical means. These compounds were found to exhibit significant antifungal activities against pathogenic fungi Rhizoctonia solani, Botrytis cinerea and Colletotrichum acutatum with MICs values of 0.02 &#8211 0.06 μM. In addition, compounds 1-4 displayed good time course motility inhibition and lytic activity against the late blight pathogen Phytophthera capsici. These compounds also showed potent antimicrobial activity against Gram positive (Bacillus subtilis and Staphylococcus aeureus) and Gram negative (Salmonella typhi and Pseudomonas aeruginosa) bacteria with MICs values of 0.04 &#8211 0.08 μM. Furthermore, to investigate the anti-inflammatory effects of the new peptides in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells, the expression of mRNA and protein using RT-PCR