초록
<P><B>Abstract</B></P> <P>Mixed carbon sources fermentation by bacteria is a promising approach for biohydrogen (H<SUB>2</SUB>) production biotechnology. In the present study, growth and Н<SUB>2</SUB> production by purple bacteria <I>Rhodobacter sphaeroides</I> MDC6521 during mixed carbon sources (succinate + acetate, succinate + malate, and malate + acetate) photo-fermentation was investigated. The growth rate of bacteria in mixed carbon sources containing medium was of ∼0.33 h<SUP>−1</SUP> which was considerably higher (1.3–1.7-fold) compared with sole carbon substrate containing one. Moreover, the H<SUB>2</SUB> production during photo-fermentation of succinate and acetate mixture was of ∼6.5 mmol H<SUB>2</SUB> g<SUP>−1</SUP> (dry weight of biomass) and significantly more (∼2–3-fold) than that with appropriate sole sources and higher (1.5-fold) than that with succinate and malate mixture. Probably, supplementation of the mixed carbon sources into bacterial culture alters the mode of metabolism, resulting in enhanced H<SUB>2</SUB> production, thus they can be preferable compared to the sole carbon source. The changed F<SUB>O</SUB>F<SUB>1</SUB>-ATPase activity of membrane vesicles suggested its important role in the increase of Н<SUB>2</SUB> production efficiency. The results showed that mixed carbon sources provide more H<SUB>2</SUB> than the sole carbon substrates and succinate with acetate mixture is better than succinate with malate.</P> <P><B>Highlights</B></P> <P> <UL> <LI> <I>R. sphaeroides</I> growth rate was higher in the presence of mixed vs. sole carbon sources. </LI> <LI> H<SUB>2</SUB> production is enhanced during photo-fermentation of succinate and acetate mixture. </LI> <LI> The F<SUB>O</SUB>F<SUB>1</SUB>-ATPase is involved in the increase of Н<SUB>2</SUB> production. </LI> </UL> </P>