Production of probiotic biomass (Lactobacillus casei) in goat milk whey: Comparison of batch, continuous and fed-batch cultures

This contribution examines the technical feasibility of producing high added value probiotic biomass from deproteinized and non-supplemented milk whey. The kinetics of growth of Lactobacillus casei in deproteinized goat milk whey was analyzed. Experiments in batch, continuous and fed-batch conditions were conducted in a 3 L fully instrumented bioreactor. Final substrate and biomass concentrations, yields and productivities are reported for different culture strategies. A kinetic analysis was conducted to characterize biomass production, product inhibition effects, and substrate consumption rates. Due to the strong product inhibition, fed-batch cultures at high biomass concentration rendered higher productivity (0.45 g L−1 h−1) than batch and continuous cultures (0.11 g L−1 h−1), complete lactose conversions (<1.0 g of lactose/L at the end of each fed-batch cycle), and a product with higher viable cell counts (2 × 1010 cell/g of freeze-dried product). Based on our result, high-cell density fed-batch strategies are recommended for commercial production of probiotic L. casei biomass.