The global food system is experiencing profound changes as a result of anthropegenic pressures. Increasing population to 9 billion and food consumption per capita means that the global food demand could increase by 70% by 2050. Food security is placing unprecedented demands on agriculture and natural resources, such as water, land, fertilizers, and fossil fuels. The World Health Organization (WHO) and Food and Agricultural Organization (FAO) recommend population nutrient intake goals for preventing diet-related chronic diseases in terms of caloric uptake: total carbohydrate (55-75%), total fat (15-30%), and protein (10-15%), where free sugars (i.e., monosaccharides and disaccharides) in the diet accounts for less than 10% of carbohydrate intake. A properly balanced diet is important to lower health risks, such as obesity, type 2 diabetes, cardiovascular diseases, hypertension, cancer and so on. In this talk, I will talk about our recent efforts for low-cost transformation of synthetic starch from cellulose. Different from microbial fermentation, we propose that the use of in vitro synthetic enzymatic biosystem (ivSB) implements complicated biological reaction via the in vitro assembly of numerous standardized and exchangeable enzymes or their complexes and/or (biomimetic) cofactors [1]. Compared to microbial fermentation, ivSB features numerous manufacturing advantages, such as high product yield, fast reaction rate, easy product separation, easy access and control for open systems, and so on. To convert cellulose to starch, we developed simultaneous enzymatic biotransformation and microbial fermentation for converting cellulose to starch and ethanol at the same time without sugar loss [2]. To decrease the production cost of synthetic starch, we develop a simple way to selectively remove beta-glucosidase from commercial cellulase mixture, display a synthetic enzyme complex on the surface of yeast to increase microbial cellulose utilization rates, and convert amylose to branched amylopectin by using a branching enzyme. In a word, we will have enough new food source to support at least 20 billion persons on earth in the future. References 1. Zhang, Y-HP. Production of biofuels and biochemicals by in vitro synthetic biosystems: Opportunities and challenges. Biotechnol. Adv. 2015:DOI: 10.1016/j.biotechadv.2014.1010.1009. 2. You C, Chen H, Myung S et al. Enzymatic transformation of nonfood biomass to starch. Proc. Nat. Acad. Sci. USA 2013; 110:7182-7187.

Making synthetic starch (amylose and amylopectin) from nonfood biomass

251st National Meeting (2016)

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