Arctic Actinomycetes as Potential Inhibitors of Vibrio cholerae Biofilm

The world wide spread of multidrug resistant bacteria is an alarming issue, as it renders antibiotics ineffective in treating infections. The biofilm structures exhibit a higher tolerance to antimicrobial agents. The formation of biofilm favors survival and persistence of Vibrio cholerae in the aquatic environment and also inside the host. The aim of this study was to identify novel biofilm inhibitors from actinomycetes isolated from the Arctic against V. cholerae, the causative agent of cholera. The biofilm inhibitory activity of actinomycetes was assessed using biofilm assay and was confirmed using air- liquid interphase coverslip assay. The potential isolates were identified using 16S rRNA gene sequencing. Of all, three Actinomycetes isolated from the Arctic, (A745, A733 and A731) showed significant biofilm inhibition against V. cholerae. Results showed that 20% supernatant of A745 induced ~88% inhibition in the biofilm formation while the other two showed 80% inhibition. The two potential isolates were found to be Streptomyces sp. and one isolate belonged to Nocardiopsis sp. (Accession No: JF903931, JF903932 and JF903933 respectively). This is the first report showing a Streptomyces sp. and Nocardiopsis sp. isolated from Arctic having a biofilm inhibitory activity against V. cholerae. The spread of drug resistant V. cholerae strains is a major clinical problem and the ineffectiveness in antibiotic treatment, necessitates finding new modes of prevention and containment of the disease, cholera. The formation of biofilms during the proliferation of V. cholerae is linked to its pathogenesis. Hence the bioactive compound from the culture supernatant of the isolates identified in this study may be a promising source for the development of a potential quorum sensing inhibitors against V. cholerae

Figure Legends

Graph showing reduction in V. cholerae biofilm formation with different percentages of actinomycetes supernatant.

Air- Liquid interphase coverslip assay. a) V. cholerae biofilm (positive control); b, c and d) Biofilm treated with supernatant of isolates A731, A733 and A745.