The continuous emergence of multiple-antibiotic resistant pathogenic bacteria requires a tremendous effort to develop new anti-virulence strategies to combat bacterial mediated diseases. Anti-virulence signaling strategies may specifically interfere with the ability of the bacteria to recognize host signals that alert the bacteria at the site of infection and/or activate specific virulence traits that are needed to establish infection. Bacterial cell–cell communication [quorum sensing (QS)] regulates expression of virulence factors in a number of bacterial pathogens and is a new promising target for the control of infectious bacteria. Marine sponges and its associated actinomycetes provide a rich source of structurally unique and bioactive secondary metabolites. Numerous genera of marine actinomycetes have been isolated from several marine sponge species. In the present study, we present the results of screening of 10 sponge extracts from the Mediterranean and Red Sea for their potential QS inhibition (QSI) activity using CV026 and LuxR-derived QSIS1 biosensor. Extracts of Suberites clavatus and Sarcotragus sp. proved active in both the systems and hence along-with four other sponges were selected for selective isolation of actinobacteria. A total of 82 strains were isolated and 50 representative isolates were selected for phylogenetic analysis. Extracts from their liquid culture media were screened for the presence of QSIs with the reporter strain Chromobacterium violaceum CVO26. Interestingly, the presence of QSI was observed widely among isolated strains demonstrating the potential for further identification of specific QSI from the marine sponge associated microbiome.
