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Recycling strategy and repression elimination for lignocellulosic-based farnesene production with an engineered Escherichia coli.

Farnesene is an importantly chemical platform for many industrial products, such as biofuels and polymers. We performed high-efficiency utilization of corncobs for β-farnesene production by separate hydrolysis and fermentation with an optimized Escherichia coli strain. First, we developed a recycling strategy for both of corncob pretreatment and cellulose hydrolysis, which saved amounts of pretreatment reagents and presented a 96.83% cellulose conversion rate into glucose. However, the corncob hydrolysate strongly repressed cell growth and β-farnesene production, being caused by high-concentrated citrate. Through expressing a heterologous ATP citrate lyase and screening for a suitable expression host, an optimized strain was constructed that produced β-farnesene at 4.06 g/L after 48 h in a 5-L fermenter, representing an approximately 2.3-fold increase over the initial strain. Therefore, the proposed strategy about recycling process and repression elimination was successful and suitable for the production of lignocellulosic-based β-farnesene, which can be further-studied to scale up for the industrialization.