title: Optimal pH control of batch processes for production of curdlan by Agrobacterium species.
abstract: We sought an optimal pH profile to maximize curdlan production in a batch fermentation of Agrobacterium species. The optimal pH profile was calculated using a gradient iteration algorithm based on the minimum principle of Pontryagin. The model equations describing cell growth and curdlan production were developed as functions of pH, sucrose concentration, and ammonium concentration, since the specific rates of cell growth and curdlan production were highly influenced by those parameters. The pH profile provided the strategy to shift the culture pH from the optimal growth condition (pH 7.0) to the optimal production one (pH 5.5) at the time of ammonium exhaustion. By applying the optimal pH profile in the batch process, we obtained significant improvement in curdlan production (64 g L-1) compared to that of constant pH operation (36 g L-1).
authors.affiliation: Bioprocess Technology Research Division, Korea Research Institute of Bioscience and Biotechnology, PO Box 115, Yusong, Taejon 305-600, Korea.
authors.initials: JH
authors.lastname: Lee
authors.initials: IY
authors.lastname: Lee
authors.initials: MK
authors.lastname: Kim
authors.initials: YH
authors.lastname: Park