Optimization of culture medium for probiotic bacterium Lacticaseibacillus casei UT1 to enhance biomass production using the Taguchi statistical method

Probiotics offer many benefits and have attracted significant research interest in recent years. Given their growing applications, large-scale mass production is essential for various industries. However, conventional media for Lactobacilli cultivation, such as MRS (de Man, Rogosa, Sharpe) and skim milk, contain expensive compounds and are therefore not ideal for probiotic-based industries. Consequently, developing a medium with low-cost ingredients, such as molasses and whey, is of utmost importance. To address this need, various carbon and nitrogen sources were first investigated using a completely randomized factorial design (CRFD) to optimize an industrial culture medium for enhancing biomass production of Lacticaseibacillus casei UT1. This screening revealed molasses + whey (MW) as the optimal carbon source and yeast extract (YE) as the optimal nitrogen source. Building on these results, the Taguchi method was then applied to evaluate these two components alongside five additional factors. The experimental outcomes were analyzed using statistical methods to determine the optimal conditions. According to the Taguchi design, the optimum formulation for biomass production of L. casei UT1 was found to be 8 % (w/v) MW, 4 % (w/v) YE, 0.04 % (w/v) magnesium sulfate, and 0.005 % (w/v) manganese sulfate. Under these optimized conditions, biomass production increased by approximately 112 % compared to the MRS medium, as predicted by the Taguchi method and confirmed experimentally.