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Surface-active compound produced by Bacillus subtilis LB5a using cassava wastewater as substrate was isolated,purified, and chemically characterized, and its infrared spectrum revealed characteristic of lipopeptide. Peptide analysisrevealed presence of glutamic acid, aspartic acid, valine, and leucine at 1:1:1.2:3.4, respectively. Electrospray ionization massspectrometry showed biosurfactant was composed of homologous lipopeptide mixture, with that of molecular weight 1035being the most abundant. Tandem mass spectrometry of each protonated molecules established the peptide sequence as R-Glu-Leu-Leu-Val-Asp-Leu-Leu. Isolated surfactant showed similar chemical composition and peptide sequence as that ofcommercial surfactin, although some differences in homologous distribution and presence of dimer molecules were detected.Preliminary biological evaluation demonstrated surfactant has potential as antiviral agent with broad spectrum of antibacterialactivity.