In this article, a low-cost medium for the production of lipopeptides by the Bacillus subtilis HSO121 was formulated with desizing wastewater as carbon source, which contains starch and its degradation products, and the lipopeptides were biosynthesized. As the result, the yield of crude lipopeptides was 1.03 g/L, and the critical micelle concentration was similar to 50 mg/L. The chemical oxygen demand of the desizing wastewater after cultivation reduced to half compared with before cultivation. Separation of crude lipopeptides and its application as soaping agents in soaping process were investigated. The optimal soaping process was obtained at pH = 9 and 75 degrees C with 0.05 g/L lipopeptides. Compared with traditional soaping process, lipopeptides soaping showed higher efficiency and higher colorfastness, and it is more energy efficient and more environmentally friendly process. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121: 1640-1646, 2011