Recent advances and perspectives on the biomass-derived production of the platform chemical triacetic acid lactone by engineered cell factories

As an important platform chemical, triacetic acid lactone (TAL) is considered the "bridge" molecule between biotransformation and chemical catalysis. The conventional production methods relying on plant extraction and chemical conversion restricted its large-scale application due to limited natural resources and serious environmental concerns. The conversion of low-cost biomass-derived carbohydrates into platform molecules by engineered microbes provides a promising alternative to produce a variety of end products with commercial values. In this review, we summarized the research progress of TAL biomanufacturing via biological approach by the metabolically engineered cell factories, including the construction of efficient biosynthetic pathways in different hosts, the development and pretreatment of biomass and industrial waste as feedstocks, and the establishment of the novel biosensor to enhance TAL synthesis. Despite the biosynthesis of TAL successfully achieved by these strategies, there are still great challenges to making the biomanufacturing of TAL economically viable. Some issues in the bio-production of TAL were discussed and potential strategies to improve the techno-economic feasibility were proposed in this review. It was hoped that these views could help to provide more rational and feasible ways for cost-efficient manufacturing of TAL by engineered microbes.