The Chinese Academy of Sciences has developed a new technology for the synthesis of starch and protein from corn straw, which has significantly reduced the cost.

Thanks to CTOnews.com netizen Xiao Zhan for the clue delivery! According to CTOnews.com news on January 30, food is the most important thing for the people, and independent food supply is the key to ensure stable economic and social development. Starch and protein are not only the main components of grain, but also important industrial raw materials.

With the rapid development of industrial biotechnology, it is possible to synthesize starch, protein and other nutrients from renewable carbon sources such as straw and carbon dioxide, which has become the focus of international biotechnology competition.

Recently, the Center for in Vitro synthetic Biology of Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, in cooperation with the Institute of Biotechnology of the Chinese Academy of Agricultural Sciences, has made new progress in the efficient synthesis of starch and microbial proteins using corn straw as substrate.

In the early stage, focusing on the starch production from straw, according to the ideas of cellulose hydrolysis, cellobiose phosphorus hydrolysis and polymerization, the team designed and created a multi-enzyme molecular machine for starch production from straw, and reconstructed the artificial metabolic transformation pathway in vitro. it broke through the key problems such as the directional rearrangement of cellulose β-1 ~ 4 glycosidic bond to starch amur1 ~ 4 glycosidic bond transformation, and realized the conversion from cellulose to starch. However, this route is faced with some problems such as low substrate energy utilization efficiency, slow conversion speed and high cost in the process of biotransformation, and it is far away from the industrial application.

Around the improvement of the economic feasibility of this route, the scientific research team devoted themselves to tackling the key problems, designed and modified the core components of multi-enzyme molecular machines, optimized the synthesis circuit, improved the efficiency of straw conversion into starch, and laid the foundation for promoting industrial application.

According to the introduction of the Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, through systematic design and transformation of recombinant enzyme expression bacteria, selection of cheap inorganic nitrogen sources to reduce the cost of culture medium, and development of high-density microbial culture, the research team has reduced the production cost of recombinant enzymes such as cellobiose phosphorylase and a-glucan phosphorylase to 250 yuan / kg.

The team used pretreated straw biomass or solid-state pretreated cellulose as affinity adsorption medium to simply and efficiently selectively adsorb endoglucanase and exoglucanase in cellulase. the β-glucosidase in cellulase was removed efficiently, and the efficient directional degradation of straw cellulose and the improvement of cellulose hydrolysis efficiency were realized.

Cellobiose phosphorylase and a-glucan phosphorylase were immobilized on the surface of Saccharomyces cerevisiae. Glucose, an intermediate product of cellulose hydrolysis, was effectively used to remove the inhibitory effect of glucose on cellulase and improve the hydrolytic ability of cellulase. and reduced the amount of cellulase. The researchers utilized the glucose produced by cellulose hydrolysis through yeast aerobic fermentation to realize the co-production of microbial protein and reduce the comprehensive cost of the transformation route.

CTOnews.com learned that the relevant research results were published on Science Bulletin. The research work is supported by Tianjin synthetic Biotechnology Innovation Initiative and National key R & D Program.