Sophorolipid Production Using Lignocellulosic Biomass by Co-culture of Several Recombinant Strains of Starmerella bombicola with Different Heterologous Cellulase Genes from Penicillum oxalicum

One of the reasons hindering large-scale application of sophorolipids (SLs) is high production cost. In this study, six recombinant strains of Starmerella bombicola , sb EG1, sbEG2, sb CBH1, sb CBH1–2, sb BGL1, and sb CBH2 expressing cellulase genes eg1 , eg2 , cbh , cbh1–2 , bgl1 , and cbh2 from Penicillium oxalicum were respectively constructed. Four strains showed cellulase activities and were co-cultivated in fermentation media containing 2% glucose, 1% Regenerated Amorphous Cellulose (RAC), 2% glucose, and 1% RAC, respectively. After 7 days’ cultivation, concentration of SLs in medium with 1% RAC (g/L) reached 1.879 g/L. When 2% glucose and 1% of RAC were both contained, the titer of SLs increased by 39.5% than that of control strain and increased by 68.8% than that in the medium with only 2% glucose. Results demonstrated that cellulase genes from filamentous fungi in S. bombicola can function to degrade lignocellulosic cellulose to produce SLs.