Bioconversion of kitchen waste to surfactin via simultaneous enzymolysis and fermentation using mixed-culture of enzyme- producing fungi and Bacillus amyloliquefaciens HM618

Abstract

Surfactin, a potent lipopeptide biosurfactant, possesses versatile bioactive properties and has potential industrial applications. However, high production costs and low yields have obstructed its large-scale industrial production. Studies on strategies to produce surfactin from kitchen waste (KW) as a low-cost substrate are indeed far lacking. In our work, we have provided two strategies for pretreating KW. Commercial enzymes (CEs) and enzyme-producing fungi were applied for KW treatment. The maximum yield of surfactin was 75.707 mg.gds−1 using Bacillus amyloliquefaciens HM618 with CE mixture-treated KW. When B. amyloliquefaciens HM618 was co-cultured with lipase-producing Aspergillus nidulan to pretreat KW, the surfactin yield was maximized to 65.404 mg.gds−1, which was higher than that under the lipase-pretreated KW alone. This co-culture system could achieve simultaneous enzymolysis and fermentation. Hence, it is feasible for enzyme producers to replace CEs to pretreat KW and achieve simultaneous enzymolysis and surfactin fermentation. Our work provides strategies for the resource utilization of KW and how to realize the synchronization of KW enzymatic hydrolysis and fermentation.