Greener Cultivation: Replacing Man Rogosa and Sharpe Agar with Beetroot and Soybean-Formulated Medium for Lactic Acid Bacteria Cultivation

Lactic Acid Bacteria (LAB), widely used in food, health, and biotechnology, have driven interest in developing sustainable plant-based alternatives to conventional culture media. This study investigates alternatives to Man, Rogosa and Sharpe (MRS) medium for their cultivation. We evaluated the efficiency of Soybean-Beetroot Blend (SBB) in supporting the growth of Lactobacillus plantarum, Enterococcus durans, and Lactobacillus fermentum. Unlike prior studies, this research aims to optimize plant-derived media to address the specific nutritional needs of LAB bacteria. Initial trials showed that beetroot and soybean, when used separately, failed to sustain adequate bacterial growth, resulting in their elimination from further testing. Enriched media formulations - SBB and beetroot juice supplemented with Tween 80 (BJ-T80)- were subsequently assessed. Results demonstrated that SBB promoted the most efficient growth for L. plantarum, with a maximum specific growth rate (µmax) of 0.248 h-¹ and a generation time of 2.79 h. In comparison, BJ-T80 exhibited a lower µmax of 0.061 h–¹ and an extended generation time of 11 h, while the MRS medium achieved a µmax of 0.154 h-¹. Acid production analysis revealed that SBB yielded a specific acid production rate (Qac) of 0.161 g/g/h and a productivity of 0.028 g/L/h. The BJ-T80 performed moderately better, with a Qac of 0.262 g/g/h and a productivity of 0.043 g/L/h, though MRS remained superior with a Qac of 1.588 g/g/h and a productivity of 2.100 g/L/h. These findings underscore the promise of beetroot-based media enhanced with plant-derived components as cost-effective and eco-friendly alternatives to conventional microbiological media.