研究期間：10108~10207;Agricultural waste is the largest resource of cellulose which can be potential substrates for production of valuable chemicals such as itaconic acid. Itaconic acid is the monomer of many commercial resins, fabrics, plastics and rubbers. Unfortunately, it is still not economic competitive if glucose is used as the substrate. In general, the cost of enzymes is relatively high; thus, the production of enzyme is the most economical approach to obtain the required cellulase. However, purification of the enzyme become the major barrier of this approach. Co-culture is another alternative using the enzyme from fermentation; however, competition of nutrients between the two cultures becomes the challenge of this approach. Metabolic engineering of the culture to produce both enzyme and itaconic acid is one of the most exciting approach; however, the efficiency of itaconic acid production is compromised. We also find that the fermentation conditions for enzyme production by Bacillus are obviously different from those of itaconic acid production by Aspergillus. Thus, the main objectives of this proposal are to develop two-stage co-culture simultaneous saccarification and fermentation (SSF) of cellulase producing cells by pH control technique, and to develop two-stage pH-control strategy for converting agricultural waste into itaconic acid. And, it might take two-year efforts to reach the goals. In other words, the project is 2-year proposal. 1st year: The objective of this year are to develop two-stage co-culture of cellulase producing cells by pH control technique, and to produce itaconic acid in the second stage. Bacillus could produce cellulase under a high pH range, and a relatively low pH was set to reduce the cell activity but not enzyme activity. 2nd year: The objective of this year is to convert agricultural waste into alcohol by a two-stage co-culture SSF of cellulose producing cells by oxygen control strategy, and to develop a novel two-stage co-culture system. The novelty of this proposal are described as below: 1. The project would be the first using two-stage co-culture system to produce required cellulase to convert agricultural wastes. 2. The project would be the first to manipulate pH control to allow a co-culture to produce IA from agricultural waste. 3. The project would be the first approach to utilize cellulose by co-culture process without using metabolic approach to produce bio-ethanol from agricultural waste. We strongly believe that the results of this project would be beneficial to both academia and industry.
