Exopolysaccharides production by Lactobacillus rhamnosus strains – Optimization of synthesis and extraction conditions

Abstract

Exopolysaccharides (EPS) synthesised by the tested strains of Lactobacillus rhamnosus bacteria (marked with symbols 0943, 0935 and OM-1) with probiotic properties are promising natural alternatives for commercial additives in the food, cosmetic and pharmaceutical industries. However, the low efficiency of synthesis and high acquisition cost make research and its industrial implementation much more difficult. In this paper, the environmental conditions and EPS extraction parameters were modelled. The culture medium used in the study was developed in the earlier stages of research on the basis of multi-parametric modelling. Thanks to a series of analyses, such cultivation parameters were developed which ensure high efficiency of EPS synthesis and a significantly reduced technological cost. The best results were obtained in stationary cultures cultivated for 24 h at 25 °C with the initial pH of 5.7 and the inoculum of 5% v/v. Unlike to other examined strains in case of Lb. rhamnosus ŁOCK 0943 prolongation of the incubation time and application of mixing (80 rpm) in the process of cultivation significantly increased the efficiency of EPS synthesis. The outcome sheds a new light on the possibility of the industrial application of the exopolysaccharides produced by Lb. rhamnosus bacteria in the “new generation” products.