Enhanced monensin production via co-fermentation of lignocellulosic hydrolysate using mutated streptomyces cinnamonensis

Co-utilization of mixed sugars from enzymatic hydrolysates is crucial for effective bioconversion of lignocellulosic biomass into value-added bio-products. This study was proposed to explore new monensin production process of Streptomyces cinnamonensis via co-fermentation of mixed sugars existing extensively in enzymatic lignocellulosic hydrolysate. Results showed that the strain S. cinnamonensis was capable of fermenting the single xylose and the mixture with glucose into monensin. At a glucose/xylose ratio of 2:1, the strain achieved a high monensin titer of 4.5 g L −1 , along with fast sugar consumption and robust microbial growth. Genomic analysis revealed that the strain metabolized the xylose through an inherent xylose isomerase pathway. With space - diethylsulfate coupled mutagenesis, a mutant S. cinnamonensis SD65 was isolated, thus resulting in the monensin titer increasing by 31 % compared with the wild-type strain (4.3 g L −1 ). The mutant produced 5.65 g L −1 and 8.96 g L −1 monensin after 192 h of the fermentation on mixed sugars, respectively, at shake-flask and bioreactor levels, almost 4 folds that of the single glucose. Interestingly, the mutant made a basically equivalent performance on the mixed sugars from enzymatic lignocellulosic hydrolysate. It was indicated that the strain S. cinnamonensis was capable of co-fermenting mixed sugars into monensin. The certain amount of xylose mixture with glucose was helpful for the microbial monensin synthesis. This study shed new light on the lignocellulosic biomass valorization and microbial monensin production. • Fermentative production of monensin from mixed sugars was first reported. • Monensin production maximized to be 4.5 g L −1 at a glucose / xylose ratio of 2:1. • S. cinnamonensis metabolized the xylose likely through xylose isomerase pathway. • Mutant strain produced 8.75 g L −1 of monensin from LCB hydrolysate in a bioreactor.