The effect of carbon source on the biomass and exopolysaccharide synthesis by Paenibacillus mucilaginosus bacteria

Paenibacillus mucilaginosus bacteria are one of the most promising soil microorganisms for obtaining microbiological fertilisers. These bacteria produce indolyl-3-acetous acid and ammonia, as well as possessing the capability of nitrogen fixation and solubilisation of undissolved soil minerals yielding potassium and phosphorus accessible to plants and consequently stimulating plant growth. P. mucilaginosus biological preparations are also useful in the form of fertiliser additives leading to immune stimulation and increase in the productivity of agricultural animals. For the cultivation of P. mucilaginosus bacterial strains, sucrose is recommended. At the same time, little research has been carried out on the influence of glucose and fructose on the growth of these bacteria. The aim of the work was to study the effect of various carbon sources in the composition of the nutrient medium on the biomass synthesis of P. mucilaginosus strains. As a result, a double growth cycle was observed under the conditions of culture on a nutrient medium with a sucrose and a glucose-fructose mixture. The specific growth rate of the bacterial strains under consideration in the assimilation of glucose is higher than in the assimilation of fructose. Accordingly, the generation time for glucose assimilation turned out to be lower than that for fructose assimilation. The growth of the considered bacterial strains on a single fructose nutrient medium was not observed. Glucose demonstrated similar effectiveness of application in culture media to sucrose for the cultivation of all considered bacterial strains of P. mucilaginosus. During culturing of P. mucilaginosus bacteria on nutrient media from glucose and sucrose, the yield of biomass and exopolysaccharides was established to be higher than for the case of a nutrient medium presented by a glucose-fructose mixture. Promising strains for industrial application include 563, 567 and 574, providing a high yield of biomass and exopolysaccharides with culture on a glucose-admixed nutrient medium, and 560, 568 and 572 strains when cultivated on a nutrient medium containing sucrose.