Green synthesis of spermidine from xylose through combination of enzyme molecular modification and metabolic engineering
Description
In this study, the accurate mutant library was constructed by rational design to screen the beneficial mutants in Bacillus amyloliquefaciens PM1 using xylose as substrate. Therein, the spermidine titers of mutants PM1/speDI39A/D22A and PM1/speEI108A/T54A were improved by 53% and 44% compared to the control strain, respectively, and the enzyme activities of the SpeDI39A/D22A and SpeEI108A/T54A increased by 58% and 44% accordingly. The mechanism of the enhanced enzymatic activity was further explained by molecular dynamics simulations. Moreover, the engineering strain PM1::D/E was constructed by combination of speDI39A/D22A and speEI108A/T54A to enhance spermidine pathway. Through fed-batch fermentation, the spermidine titer reached 683.14 mg/L, which was higher than previous reports in shake flask fermentation. This study provides a novel strategy for green synthesis of spermidine from xylose, which will promote the clean and efficient production of spermidine.