Biotechnological Valorization of Certain Medicinal Plants from Western Algeria

Abstract

This thesis explores the potential of Algerian-sourced beetroot (Beta vulgaris), supplemented with additives or combined with carob pods and soybeans, as a sustainable alternative to conventional Man, Rogosa, and Sharpe (MRS) agar for cultivating Lactic Acid Bacteria (LAB). This study investigates the performance of these formulated plant-based media in supporting the growth of Lactobacillus plantarum, Lactobacillus fermentum, and Enterococcus durans, focusing on growth rate, time of generation, acid production and productivity. Various formulations, including Beetroot Juice with functional additives like Manganese sulfate (MS) and ammonium citrate (AC) were tested, along with carob-beetroot and soybean-beetroot blends. Results showed that beetroot juice alone was insufficient for bacterial growth, but mineral supplementation significantly improved microbial performance. For instance, the carob-beetroot blend (CBB) yielded µmax values of 0.251 h⁻¹ for L. plantarum and 0.275 h⁻¹ for L. fermentum, along with an acid production rate (Qac) of 4.051 g/g·h for L. fermentum. Additionally, the soybean-beetroot blend (SBB) supported L. plantarum growth with a µmax of 0.248 h⁻¹ and a generation time of 2.79 h, while maintaining consistent acid production (Qac = 0.161 g/g·h). In comparison, MRS displayed a µmax of 0.154 h⁻¹ and higher acid production (Qac = 1.588 g/g·h). These findings suggest that plant-based beetroot media could replace MRS in LAB cultivation, providing a sustainable, cost- effective, and biodegradable alternative for fermentation processes in food biotechnology.