Optimization of medium composition for the production of compounds effective against Xanthomonas campestris by bacillus subtilis

Abstract

The biocontrol agents are a very promising alternative to synthetic pesticides that are presently used to control plant diseases caused by phytopathogenic microorganisms. Members of the Bacillus genera are soil bacteria that produce significant quantities of agriculturally important bioactive compounds. Production of these compounds can be improved by changing the nutritional and environmental conditions. The aim of this study was the optimization of medium composition, using response surface methodology, for the production of compounds effective against Xanthomonas campestris ATCC 13951 by Bacillus subtilis ATCC 6633. To study the production of antimicrobial compounds by selected Bacillus strain, the producing microorganisms were cultivated on nutrient broth. The inhibition zone diameter of 18.0 mm obtained by the diffusion-disc method indicated that the used Bacillus subtilis strain produces compounds with antimicrobial activity against Xanthomonas campestris ATCC 13951. To optimize the composition of the cultivation medium in terms of glycerol, sodium nitrite and phosphates content, experiments were carried out in accordance with Box-Behnken design, and optimization of multiple responses was performed using the concept of desirability function. The developed model predicted that the maximum inhibition zone diameter (26.23 mm) against tested phytopathogen is achieved when the initial content of glycerol, sodium nitrite and phosphate were 50.00 g/L, 2.85 g/L and 11.00 g/L, respectively. To minimize the consumption of medium components and costs of effluents processing, additional optimization set was made. The techno-economic analysis of the obtained results has to be done to select optimal medium composition for industrial production of antimicrobial compounds.

Production of biocontrol agents using Bacillus sp. in a laboratory-scale bioreactor

“…Considering that only a small share of each nutrient was depleted by the producing microorganism and used for growth and metabolic activity, and the fact that the applied nutrients remained, for the most part, in the cultivation broth after the cultivation process, it can be concluded that further optimization of the cultivation medium composition should be reviewed. The optimization of the cultivation medium composition in this case implies the reduction of the initial nutrient contents in order to decrease the residual nutrient contents and improve bioprocess productivity, as well as to lower total bioprocess costs, which are conditioned by the reduction in the cultivation medium price and the costs of necessary effluent treatments (Rončević et al, 2014). Furthermore, a techno-economic analysis relative to the bioprocess duration should be performed in order to determine whether the bioprocess costs could be reduced by shortening the cultivation time.…”

Optimization of cultivation medium composition for production of bioactive compounds effective against Penicillium sp.

“…appropriate selection of nutrient sources (mostly of carbon, nitrogen and phosphorus) and precise defining of their concentrations, is the main method of directing metabolic activity of productive microorganisms towards biomass growth or synthesis of metabolites with antimicrobial activity (Sanchez & Demain, 2002). It is also important to optimize medium composition in terms of nutrient quantities that remain in cultivation broth after the biosynthesis in order to reduce the cost of effluents treatment and environmental pollution (Rončević et al, 2014).…”

Formulation of medium for bactericides biosynthesis using wild type Streptomyces sp.

“…Since the microbiological production of antibacterial components is affected by many factors, it is usually very difficult to determine which of them has the greatest impact. Therefore, RSM is increasingly used for mathematical modeling and optimization of the biotechnological production of these compounds [14,[19][20][21][22][23]. This research represents a major challenge for scientists because the biotechnological processes are difficult to describe by mathematical equations due to the complex metabolism of producing a microorganism, the usage of raw materials of undefined composition, and the changes that occur during the bioprocess being performed at selected technical and technological parameters.…”