초록
<P><B>Abstract</B></P> <P>In this study, the response surface methodology (RSM) with central composite design (CCD) was employed to improve the hydrogen production by the psychrophilic N92 strain (EU636058) isolated from Antarctica, which is closely related to <I>Pseudorhodobacter</I> sp. (KT163920). The influence of operational conditions such as temperature (4.7–55.2 °C), initial pH (3.44–10.16), and initial glucose concentration (4.7–55.23 g/dm<SUP>3</SUP>), as well as the initial concentrations of (NH<SUB>4</SUB>)<SUB>2</SUB>SO<SUB>4</SUB> (0.05–3.98 g/dm<SUP>3</SUP>), FeSO<SUB>4</SUB> (0.02–1.33 g/dm<SUP>3</SUP>) and NaHCO<SUB>3</SUB> (0.02–3.95 g/dm<SUP>3</SUP>) was evaluated. The linear effect of glucose concentration, along with the quadratic effect of all the six factors were the most significant terms affecting the biohydrogen yield by N92 strain. The optimum conditions for the maximum hydrogen yield of 1.7 mol H<SUB>2</SUB>/mol glucose were initial pH of 6.86, glucose concentration of 28.4 g/dm<SUP>3</SUP>, temperature 29 °C and initial concentration of (NH<SUB>4</SUB>)<SUB>2</SUB>SO<SUB>4</SUB>, FeSO<SUB>4</SUB> and NaHCO<SUB>3</SUB> of 0.53, 1.55 and 1.64 g/dm<SUP>3</SUP> respectively. Analysis of the metabolites produced under the optimum conditions showed that the most abundant were acetic acid (0.8 g/dm<SUP>3</SUP>), butyric acid (0.7 g/dm<SUP>3</SUP>) and ethanol (2.1 g/dm<SUP>3</SUP>). We suggest that the bioprocess established in this study using the strain N92 could be an alternative for hydrogen production with the advantages of constituting low energy costs in fermentation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The N92 strain (EU636058) can produce hydrogen from glucose. </LI> <LI> Hydrogen production by N92 strain was optimized by using two experimental designs. </LI> <LI> The optimum temperature for hydrogen production by N92 strain was 29 °C. </LI> <LI> The N92 strain may be used for hydrogen production at ambient temperature. </LI> </UL> </P>