Purple Sulfur Oxidizing Bacteria: Model Reconstruction and FluxBalance Analysis

Sulfur containing contaminants released into environment have become an environmental issue due to their hazardsand threats to human health and ecosystems. Various chemical, physical and biological methods have so far been usedto remove these compounds. Application of purple phototrophic sulfur-oxidizing bacteria has shown advantages overconventional biological method. These microorganisms perform anoxygenic photosynthesis alongside utilization ofvarious sulfur compounds as electron donors and are known for production of elemental sulphur as desired product.Purpose:Providing insights into metabolism of these group of microorganisms in particular their cell growth and product for mation.Method:Firstly, a metabolic network (۹۹ reactions) including oxidation of sulfur compounds, central carbon metabolism,synthesis of various biomolecules and the exchange reactions for nutrients and products was recon structed for the purple sulfur bacteria (PSB). Subsequently, the model was solved using COBRA tool box in MATLAB software and flux distributions within cell under different conditions were examined.Result:It was shown that the specific growth rate was optimized (۰.۰۴۲ h-۱) when sulfide was consumedas electron donor, with ۷.۵۷۶ mmol/gDwh of light required for ۱ mmol/gDwh of sulfide uptakeand sulfate formation as the only product. However, the flux of sulfur as the desirable prod uct was maximized at ۲ mmol/gDwh of light consumption with specific growth rate of ۰.۰۱۱ h-۱.Conclusion:The reconstructed metabolic model for PSB can have economic usage in the industrial removal of sulfur contaminantsdue to using natural light as the energy source and producing elemental sulfur as the appropriate product

کلیدواژه ها:

Distribution of intracellular fluxes ، FBA ، Purple sulfur bacteria ، Sulfur phototrophic metabolism