Bacterial Aggregation Assay in the Presence of Cyclic Lipopeptides.

Lipopeptides is an important class of biosurfactants having antimicrobial and anti-adhesive activity against pathogenic bacteria. These include surfactin, fengycin, iturin, bacillomycin, mycosubtilin, lichenysin, and pumilacidin ( Arima et al., 1968 ; Naruse et al., 1990 ; Yakimov et al., 1995 ; Steller and Vater, 2000; Roongsawang et al., 2002 ; Vater et al., 2002 ). To date, none of these lipopeptides have been reported to possess any anti-motility activity. We isolated, purified and characterized two novel cyclic lipopeptides (CLPs) from Bacillus sp. 176 using high performance liquid chromatography, mass spectrometry and nuclear magnetic resonance spectroscopy. CLPs dramatically suppress the motility of pathogenic bacterium Vibrio alginolyticus 178, and promote cellular aggregation without inducing cell death. Cell aggregation assay was performed with the modification according to methods described by Dalili for anti-biofilm assay ( Dalili et al., 2015 ). In future, this assay can be adapted to test both the cell aggregation and anti-biofilm activity of lipopeptide-like active substances derived from bacteria.