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Coenzyme Q₁₀ (CoQ₁₀) is a component of the respiratory chain that is responsible for generating energy by transmitting electrons. Today, due to the increasing demand for CoQ₁₀, its production is increasing. In this study, the effect of extract containing of carotenoid from bell pepper as a precursor was investigated on CoQ₁₀ production by Gluconobacter japonicus FM10. For this purpose, at first the total carotenoid was extracted from four colors of bell peppers and then the minimum inhibitory concentration of these extracts was measured. In the next step, the effect of extracts was investigated on CoQ₁₀ production in two phases of the exponential and stationary. The results showed that CoQ₁₀ production was increased in the presence of the bell pepper extract (4.1 mg / L in the presence of red bell pepper extract). In fact, 1.5 times more than when no extract was added. Adding red pepper extract in the exponential phase also increased CoQ₁₀ to 4.9 mg / L, while adding it in the stationary phase did not affect CoQ₁₀ increasing. Therefore, it can be concluded that the carotenoid in bell pepper extract increase the production of CoQ₁₀ by affecting cell growth and increasing it. Therefore, the carotenoid-extract of bell pepper can be introduced as a suitable precursor to increase CoQ₁₀ production.

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Mutation in microbial strains to increase coenzyme Q₁₀ production is one of the successful strategies for strain development. Therefore, in this study, the production of coenzyme Q₁₀ by Gluconobacter oxydans H621 was investigated through chemical mutation with nitrosoguanidine using the response surface methodology. Nitrosoguanidine was used to induce mutations at different concentrations (2.79 - 4.21 mg/mL) and treatment times (11.89 – 33.12 minutes), which was designed by a central composite design. The detection of mutant strains was investigated through their ability to grow in medium containing 160 μg/mL of menadione. The mutant strains were then examined for coenzyme Q₁₀ and dry cell weight production. The results showed that no mutant strains were obtained at a concentration of 4 mg/ml and above. The highest number of mutant colonies was obtained at a concentration of 2.79 mg/mL of nitrosoguanidine and treatment time of 22.5 minutes. It was also found that the concentration of nitrosoguanidine was effective on mutagenesis but the treatment time had a little effect. The mutant strain that was able to produce the highest amount of coenzyme Q₁₀ produced 5.2 mg/L, which was twice as much as the parent strain. According to the results of this study, it is concluded that by inducing mutation using nitrosoguanidine, mutant strains can be generated in Gluconobacter oxydans H621 that are able to produce more coenzyme Q₁₀ than the parent strain.