酿酒酵母细胞表面展示技术在农林废弃物生物炼制中的最新进展

With the increasing demand for fossil fuels and growing environmental concerns,biomass has emerged as the most attractive alternative among fuel sources and sustainable energy sources on the planet.Biomass such as cellulose from agricultural and forestry residues or industrial wastes is recognized as an ideal sustainable source of sugar for the production of biofuels and biochemical.Agricultural and forestry wastes are produced in large quantities worldwide,causing some waste of resources and environmental problems.From the perspective of circular economy,the central task is to refine agricultural and forestry wastes to produce valuable energy and chemicals.Microbial conversion is safe,environmentally friendly compared to chemical conversion methods,can produce target proteins quickly and efficiently,and can also result in higher yields,lower costs,and less waste.Microbial cell surface display technology is a novel and cost-effective technology that provides a powerful platform for engineering proteins/peptides with enhanced properties.Compared to the classical intracellular and extracellular expression(secretion)systems,this technology avoids enzyme purification,substrate transport processes,and is an effective solution to enzyme instability.Saccharomyces cerevisiae is well suited to cell surface display as a common cell factory for the production of various fuels and chemicals,with the advantages of large cell size,being a Generally Regarded As Safe(GRAS)organism,and post-translational processing of secreted proteins.Various enzymes such as cellulase,hemicellulase,lipase,amylase,cyclodextrin dextran converting enzyme,and amylase have been successfully expressed on the surface of yeast cells and are biologically active.The successfully constructed engineered strains not only effectively degrade lignocellulose-and starch-rich agricultural and forestry wastes,but also lay the foundation for the simultaneous saccharification fermentation(SSF)/consolidation bioprocessing(CBP)process.Cell surface display technology can be used to produce biofuels and a variety of chemicals from inexpensive sources of biomass rich in sugars,triglycerides and waste proteins.In addition,it is widely used in biosorbents and oral vaccines.Combining metabolic engineering and synthetic biology approaches,engineered yeast cells with desired functions can be constructed.In this review,we first describe various strategies for constructing modified S.cerevisiae using cell surface display technology,including direct cell surface display and scaffold-mediated cell surface display strategies.Meanwhile,this paper focuses on the application of S.cerevisiae cell surface display technology for agricultural and forestry waste biofinerie.The improvement of cell surface display efficiency depends on the effective expression and secretion of target proteins as well as the activity of the displayed target proteins.This paper summarises the strategies to improve the efficiency of cell surface display in S.cerevisiae,including the selection of anchoring domains and localization effects,the enhancement of protein secretion and expression,and the optimization of cell surface space utilization.Finally,the difficulties faced by the cell surface display technology are discussed and the future development prospects are envisaged.