چكيده به لاتين
Today, the use of microorganisms has received much attention. For this reason, it is necessary to examine their behavior in different conditions.
Since oxidizing bacteria of sulfur compounds are playing a pivotal role in removing pollutants, in this project, the rate of growth and production of their products has been investigated by the help of a metabolic model. The current model contains 110 reactions and 93 metabolites, which include carbon central pathways, synthesis of biomolecules, exchange reactions of input sources, products and oxidation reactions of sulfur compounds. MATLAB software and Cobra toolbox are used in the implementation of the project. In the first step, the effect of different sources of organic carbon, and after that the effect of nitrogen source and the amount of oxygen limitation on the production of biomass and products were examined. Finally, the amount of biomass production in terms of carbon atoms is compared in three metabolisms: chemoautotroph, chemoheterotroph and mixotroph.
Three sources of organic carbon, glucose, pyruvate and acetate, are used to check the growth rate. The result indicated that the highest amount of biomass production was related to growth on glucose carbon source. Regarding the nitrogen source, biomass production performance in ammonia has been better than nitrate. In order to investigate the effect of oxygen limitation on crop growth and production, four sulfur substrates including hydrogen sulfide, elemental sulfur, thiosulfate, and tetrathionate were used, and each time growth took place on each of them, and It was observed that by reducing the amount of oxygen, we see less growth and variety in the production of products. According to the results obtained from this experiment, in the case of no limitation in the amount of oxygen, the highest amount of biomass production is related to growth on hydrogen sulfide (2.9888 1/h) and the lowest amount is related to growth on tetrathionate (2/9285 1/h) and sulfate is the only sulfur product coming out of the network. However, by decreasing the amount of oxygen, the process of production of products changes and the production of sulfate decreases. Also, when growing on tetrathionate, the amount of biomass production in terms of carbon atoms in mixotrophic metabolism (0.054 gDW cells/(mmol C-atom) is less than autotrophic metabolism (0.056 gDW cells/(mmol C-atom)) and It is more than heterotrophic metabolism (0.048 gDW cells/(mmol C-atom)). The results of this project are in acceptable agreement with the results found in the articles.
