Multi-objective optimization of nutrient medium composition using model prediction of Streptomyces recifensis biosynthesis process

Abstract

Secondary metabolites synthesized by the producer Streptomyces are widely used in the food, pharmaceutical, cosmetic, textile, and agricultural industries. These industries around the world are developing rapidly, as a result of which they need new engineering solutions that should increase the yield of the final product and optimize the production process. Understanding the dependence of the optimal correlation of the components of the nutrient medium on the increase in the biosynthesis of secondary metabolites by the producer Streptomyces will promote the development of these industries in economic and ecological aspects. In this study, we optimized the quantitative correlation of twelve (6+6) components of the nutrient fermentation medium for Streptomyces recifensis var. lyticus 2P-15. For optimization we used the simplex method of mathematical modeling of the optimization conditions of the biotechnological process. After optimization, a 6.36 times increase in the level of biosynthetic capacity was obtained compared to the control version of the medium. To determine the dynamics of biosynthesis, samples of culture fluid were taken. Sampling was carried out every 24 hours of cultivation, the dynamics of pH diapason, biomass accumulation in mg/ml and amylolytic activity in U/mL were determined. The correlation of amylolytic activity to the level of biomass accumulation was taken as the biosynthetic capacity of the strain. A photocolometric method based on the starch-iodine method was used to determine amylolytic activity. The volume of biomass accumulation was determined by a weighted method. As a result of the optimization, the composition of the nutrient medium was developed, in which the degree of synthesis of amylolytic enzymes increased by 6.11 times, and there was a significant increase in biomass accumulation, while the cost of the optimized medium was reduced by 1.5–2.0 times from the initial one. Positive dynamics were studied when new components were introduced into the environment, such as sodium glutamate and corn extract. Optimum concentrations of monosodium glutamate were established at 0.5% of the volume of the nutrient medium and corn extract at a concentration of 1%, respectively. The significance of the positive effect upon the introduction of heavy metal ions and some vitamins into the medium was also checked, the obtained results provide an opportunity for further research into these aspects of the composition of the nutrient medium. The advantage of biotechnological developments in matters of industrial enzymology is the opportunity to obtain not only raw materials for the pharmaceutical or other industries (where it will only acquire a final form), but also produce as a final product in a ready, convenient form. Enzyme preparations of microbial origin, which can be obtained from the studied strain, have unique properties (efficiency and specificity of action, non-toxicity, ability to work in mild conditions, to process various raw materials of plant and animal origin), in connection with which their use in industry will be profitable from the economic and ecological point of view.