Fed-batch fermentation for production of Kluyveromyces marxianus FII 510700 cultivated on a lactose-based medium.

A strain of Kluyveromyces marxianus was grown in batch culture in lactose-based media at varying initial lactose concentrations (10-60 g L(-1)) at 30 degrees C, pH 5.0, dissolved oxygen concentrations greater than 20%. Increasing the concentration of mineral salts three-fold at 40 g L(-1) and 60 g L(-1) initial lactose concentration showed only a small increase in the yield of biomass, from 0.38 g g(-1) to 0.41 g g(-1), indicating that the initial batch cultures were not significantly nutrient- (mineral salts)-limited. A relatively high biomass concentration (105 g L(-1)) was obtained in fed-batch culture following extended lactose feeding. An average specific growth rate (0.27 h(-1)), biomass yield (0.38 g g(-1)) and overall productivity (2.9 g L(-1) h(-1)) were obtained for these fed-batch conditions. This fed-batch protocol provides a strategy for achieving relatively high concentrations and productivities of K. marxianus on other lactose-based substrate streams (e.g., whey) from the dairy industry.