Progress 09/01/02 to 08/31/04
Outputs
This project has successfully completed all the technical tasks in the original proposed plan of work. All objectives of the project have been met. Briefly, they are described below. (1) By controlling the supply of trace metals and also by the use of xylose in early stage of cell growth, we have successfully controlled the pellet size to be 1 mm or smaller. A large sized pellet will have oxygen starvation at the interior of the pellet, reducing the fumaric acid yield. (2) By adding carbon dioxide either as a gas or in the form of sodium bicarbonate, the yield of fumaric acid as calculated from the amount of glucose consumed has been increased from about 50 grams to 80 grams per 100 grams of glucose. This is because, as we have proven, the carbon dioxide is fixed by the metabolic activities of the fermenting fungal cells of Rhizopus oryzae and become a second carbon source for the cells in addition to glucose. (3) By using a coupled ion exchange column, fumaric acid
was successfully isolated from the fermenting broth simultaneous to the fermentation process. The adsorbed fumaric acid was easily desorbed from the ion exchange resins and reabsorbed by solid zeolite particles. Free fumaric acid is then isolated and purified from the zeolite with zeolite regenrated for reuse. This novel techique prvents built-up of fumaric acid inside the fermentation broth. A high conentration of fumaric acid and/or its salt always has the possibility of abrupt precipitaing out in the fermentor preventing the completion of the batch. With additional results in the successful recycle of the pre-formed pellets and also proper selection of reactor designs, the Phase II was completed satisfactorily.
Impacts
This project was on the development of a new process for the production of fumaric acid from corn by fermentation. Fumaric acid has many uses. Currently, all fumaric acid in the market is provided by petrochemical processing. This new project will be the very first one to produce this product by biological method from renewable resource. With the price of pretroleum crude approaching $50 per barrel, the interests in producing fumaric acid from renewble starch is rising. The technical advances made in this project as briefly described above increases the productivity of fumaric acid considerably. With fumaric acid sold at $0.82 per pound and glucose raw material at $0.10 per pound, a biological industry producing fumaric acid by the process reported in here should be potentially very profitable. Fumaric acid can be converted by additional biological processing into malic acid. A private company is in discussion with the PI for possible technology transfer to use our
fumaric acid to replace the fumaric acid they purchase from petrochemical companies. Fumaric acid is also the raw material for making another biological acid called aspartic acid which is used in large volumes in making artificial sweeteners and also potentially biodegradable detergents and plastics. The future market volume of fumaric acid can be very large.
Publications
- None (2004). The results will be kept for technology transfer and commercialization uses.
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Progress 10/01/02 to 09/30/03
Outputs
We ahve successfully restricted the pellet size of the Rhizopus mycelia to about 1 mm in diameter. With small pellets, we were able to provide adequate oxygen supply to the cells resulting in high yield of fumaric acid from glucose. The weight yield has reached over 80 grams per liter from 103 grams per liter of glucose in 72 hours. The productivity has reached 1.14 grams per liter per hour. Additional work is planned for the next year (second year of a two year project) to use either air lift columns or bubble columns as the reactor for the acid production. These designs of reactors are much less expensive than those of stirred and sparged tanks. We expect to further reduce the production cost of fumaric acid to compete with the same product produced currently from petroleum. The mycelial pellets can be recovered and reused as biocatalysts. After 6-8 rcycles the activity can be reactivated to original level by feeding the still alive cells with more nitrigen source
such as urea. We have also been trying to use solid zeolite in regeneration of fumaric acid from ammonium furmarate. We have enjoyed so far some success. Additional work is planned for the second year.
Impacts
After successfully tested the three important processing technique: formation of small pellets for good oxygen transfer, reuse of the same pellets and their reactivation by regrowth and recovery of free acid using solid acid avoiding wastes, we should have a process that can produce fumaric acid from glucose and other renewable carbohydrates to be economically competitive against the same product from petrochemical industry.
Publications
- No publications reported this period
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