An efficient method for separation of surfactin from Bacillus amyloliquefaciens fmb50 broth by flocculation

An efficient method for removing microbial cells and macromolecular impurities and purification of surfaction from fermentation broth produced by Bacillus amyloliquefaciens fmb50 was carried out in this study. Among three inorganic flocculants and a macromolecular flocculants, the combination use of CaCl2 and Na2HPO4 was the most effective separation process. Addition of 50% ethanol into fermentation broth could not only disrupt the surfactin micells, but also promote the permeating of surfactin in filtration. The flocculation condition was optimized by an L9 (34) orthogonal design. The light transmittance, surfactin recovery rate, protein removal rate and filtration flux could reach to 96.3%, 95.31%, 56.59% and 3204.41 L m−2 h−1 respectively, the surfactin purity reached to 79.5% and the residual protein was 8.1% in separated product under the optimal flocculation condition (flocculants dosage 0.5%, pH 5.0, and temperature 35 °C). Validation test also demonstrated stable results under the optimal conditions. Due to higher efficiency, lower cost and scale-up more easily of flocculation and filtration processes, it is feasible to separate surfactin from fermentation broth.