System metabolic engineering strategies for 2，3-butandione production by Torulopsis glabrata

Abstract:

Abstract:［Objective］We regulated the carbon flux distribution of Torulopsis glabrata CCTCC M202019，an efficient pyruvate-producing microorganism，for improved 2，3-butandione production.［Methods］ We overexpressed the acetolactate synthase (ALS) from Bacillus subtilis and then used the genome-scale metabolic model (GSMM) for T．glabrata (named iNX804) to evaluate the importance of deleting the ILV5 gene． In addition，the BDH gene was deleted to restrict the degradation of 2，3-butanedione.［Results］Overexpression of the ALS resulted in a 4. 6-fold increase in ALS activity and increased the extracellular concentration of 2，3-butanedione to 0.57 g/L from 0.01 g/L. The deletion of the ILV5 gene was found to increase the 2，3-butanedione accumulation level by 28.1% ，attributed to the disruption of Lvaline and L-leucine biosynthetic pathway． With the deletion of the BDH gene，the enzyme activity levels of butanedione reductase and butanediol dehydrogenase were decreased by 74.4% and 76.1%，respectively．And the accumulations of 3-hydroxybutanone and 2，3-butanediol were decreased by 52.2% and 71.4%，respectively．The final 2，3-butanedione concentration was 0.95 g/L，which was 30.1% higher than that of the control strain.［Conclusion］The GSMM based system metabolic engineering can be a functional strategy to redistribute the carbon flux from pyruvate node to 2，3-butanedione and achieve efficient accumulation of 2，3-butanedione.