title: Optimization of L-lactic acid feeding for the production of poly-D-3-hydroxybutyric acid by Alcaligenes eutrophus in fed-batch culture.
abstract: We investigated optimization of the feeding of L-lactic acid for the production of poly-D-3-hydroxybutyric acid [P(3HB)] by Alcaligenes eutrophus in a fed-batch culture system. An acidic substrate solution was fed automatically so as to maintain the pH of the culture liquid at 7.0. Feeding of a substrate solution containing 45% (w/v) L-lactic acid, 6.2% (w/v) sodium L-lactate, 5.8% (w/v) ammonia water and 1.8% (w/v) potassium phosphate [at a molar ratio of carbon to nitrogen (C/N molar ratio) of 10], allowed the L-lactate concentration in the culture liquid to be maintained at approximately 2 g/l and the cell concentration reached 27.4 g/l after 15 h of cultivation. To promote P(3HB) production, a two-stage fed-batch culture consisting of a culture for cell growth and one for P(3HB) accumulation was carried out. When the substrate solution, whose C N molar ratio was 23, was fed during the P(3HB) accumulation phase, the cell concentration and the P(3HB) content in the cells reached 103 g/l and 57.6% (w/w), respectively, in 51.5 h.
authors.affiliation: Department of Food Science and Technology, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Fukuoka 812-8581, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Tsuge
authors.forename: K
authors.initials: K
authors.lastname: Tanaka
authors.forename: M
authors.initials: M
authors.lastname: Shimoda
authors.forename: A
authors.initials: A
authors.lastname: Ishizaki