Discovery of design strategies for enabling pyrolytic sugars tolerance and utilization by Escherichia coli

Biorenewable biomass has been extensively utilized as an appealing source of carbon and energy for the production of biochemicals and biofuels via biological fermentation to meet the increasing demand of petroleum-based products. A variety of biomass resources have been used such as dedicated crops and wastes including agriculture residue and forestry. Lignocellulosic biomass is consisting of hemicellulose, cellulose and lignin, which is either composed of polysaccharides or phenolic compounds that cannot be metabolized by microorganisms directly. Thus, deconstruction of biomass into fermentable sugar monomers is of great importance. There are a variety of physical or chemical pretreatment methods that have been developed, including the use of acids, alkali, steam, oxidants and high pressure. Fast pyrolysis, which is a type of thermochemical processing, is used in this study. It is an attractive approach to produce pyrolytic sugar syrup due to the advantages such as the flexibility of the feedstocks and the rapidness of reactions. However, the common issue of this bioconversion platform is that a variety of co-products are formed from the pretreatment process, such as phenolic compounds, aldehydes, which have been proved inhibitory to biocatalysts. Therefore, to improve the tolerance and utilization of biocatalysts to the biomass-derived sugars is necessary for increasing the production of target compounds. To overcome this challenge, several strategies have been performed to enable biocatalysts to survive the deterious living environment. The first approach is to reduce the toxicity of the biomass-derived sugars by removing the inhibitors. For example, detoxification of the sugars by the chemical treatments with alkali, oxidants or physical