Biotransformation of ethylene glycol by engineered Escherichia coli

There has been extensive research on the biological recycling of PET waste to address the issue of plastic waste pollution,with ethylene glycol(EG)being one of the main components recovered from this process.Therefore,finding ways to convert PET monomer EG into high-value products is crucial for effective PET waste recycling.In this study,we successfully engineered Escherichia coli to utilize EG and produce glycolic acid(GA),expecting to facilitate the biological recycling of PET waste.The engineered E.coli,able to utilize 10 g/L EG to produce 1.38 g/L GA within 96 h,was initially constructed.Subsequently,strategies based on overexpression of key enzymes and knock-out of the competing pathways are employed to enhance EG utilization along with GA biosynthesis.An engineered E.coli,characterized by the highest GA production titer and substrate conversion rate,was obtained.The GA titer increased to 5.1 g/L with a yield of 0.75 g/g EG,which is the highest level in the shake flake experiments.Transcriptional level analysis and metabolomic analysis were then conducted,revealing that overexpression of key enzymes and knock-out of the competing pathways improved the metabolic flow in the EG utilization.The improved metabolic flow also leads to accelerated synthesis and metabolism of amino acids.

Design and construction of microbial cell factories based on systems biology

Environmental sustainability is an increasingly important issue in industry.As an environmentally friendly and sustainable way,constructing microbial cell factories to produce all kinds of valuable products has attracted more and more attention.In the process of constructing microbial cell factories,systems biology plays a crucial role.This review summarizes the recent applications of systems biology in the design and construction of microbial cell factories from four perspectives,including functional genes/enzymes discovery,bottleneck pathways identification,strains tolerance improvement and design and construction of synthetic microbial consortia.Systems biology tools can be employed to identify functional genes/enzymes involved in the biosynthetic pathways of products.These discovered genes are introduced into appropriate chassis strains to build engineering microorganisms capable of producing products.Subsequently,systems biology tools are used to identify bottleneck pathways,improve strains tolerance and guide design and construction of synthetic microbial consortia,resulting in increasing the yield of engineered strains and constructing microbial cell factories successfully.