Increasing Biosynthesis of Carotenoid by Deinococcus radiodurans R1 in the Presence of Tricarboxylic Acid Cycle Intermediates Using Response Surface Methodology

Abstract

Abstract Background: The application of carotenoids in the pharmaceutical industry has received great attention in recent years. In this regard, the radiation-resistant extremophile microorganisms have shown to be promising source of carotenoids. However, the optimization of their metabolite production is critical for large-scale commercial purpose. Methods: In the present study, the influence of process parameters (medium pH, carbon and nitrogen source) on the carotenoid production by a polyextremophile microorganism, Deinococcus radiodurans R1 (ATCC 13939), was evaluated using the response surface methodology. A total of 32 experiments at five levels for each factor were analyzed using the Design Expert 7 software. Results: According to the results, the response surface methodology was a robust optimization method to enhance the production of carotenoid by Deinococcus radiodurans R1 (52.3 mg/L) by 21.8-fold more than the unoptimized conditions (2.4 mg/L). The optimum cultural condition for carotenoid biosynthesis using the studied strain was observed in the fermentation medium (pH 7) containing citrate (10 mM), malate (15 mM), succinate (10 mM), and glutamate (10 mM). Conclusion: Overall, the results of this study revealed that the microbial biomass and carotenoid production were affected by malate more significantly than other studied tricarboxylic acid cycle intermediates. Keywords: Carotenoid, Deinococcus radiodurans R1, Optimization, Response Surface Methodology