title: Production of Bacillus thuringiensis spores in total cell retention culture and two-stage continuous culture using an internal ceramic filter system.
abstract: The production of Bacillus thuringiensis spores was investigated in a bioreactor incorporating a ceramic membrane filter to improve spore concentration and volumetric productivity. Two cultivation methods were used in this study: a total cell retention culture (TCRC), and a two-stage continuous culture with partial cell bleeding. In the TCRC, fed by 50 g/L of glucose, a spore concentration of 1.6 x 10(10) CFU/mL was obtained with a spore percentage of greater than 95% and a maximum cell mass of 82.2 g/L. The volumetric productivity was four times higher than that obtained from batch cultivation. In the two-stage continuous culture with partial cell bleeding spore concentration was strongly dependent on the bleed ratio. The spore concentration of 1.8 x 10(9) CFU/mL and the spore percentage of 70% were obtained at the second stage when a bleed ratio of 0.33 and a dilution rate of 0.23 h(-1) were used.
authors.affiliation: BioProcess Engineering Research Center and Department of Chemical Engineering, Korea Advanced Institute of Science and Technology, 373-1 Kusung-dong, Yusung-gu, Taejon 305-701, Korea.
authors.forename: B C
authors.initials: BC
authors.lastname: Kang
authors.forename: S Y
authors.initials: SY
authors.lastname: Lee
authors.forename: H N
authors.initials: HN
authors.lastname: Chang