초록
<P><B>Abstract</B></P> <P>Photofermentative hydrogen production from synthetic mixtures of lactose and lactate mimicking cheese whey was modeled and optimized using Design of Experiments and Response Surface Methodology. Five continuous parameters (light intensity, pH, lactose, lactate and glutamate concentrations) were studied as a function of buffer type (KPi or Borax) using two recombinant bacterial strains. For <I>Rhodobacter capsulatus</I> B10(<I>lacZ</I>), buffer type influenced the optimal parameter values but the optimal responses were similar in both buffers. In contrast, for <I>R. capsulatus</I> IR3(<I>lacZ</I>), responses were higher in Borax buffer than in KPi and were significantly higher than in strain B10(<I>lacZ</I>). Thus, the experimental optimized responses for specific volumetric H<SUB>2</SUB> production, volumetric H<SUB>2</SUB> production rate and substrate (lactose plus lactate) to H<SUB>2</SUB> conversion rate in Borax buffer, were 12,150 ml L<SUP>−1</SUP>, 48.5 ml L<SUP>−1</SUP> h<SUP>−1</SUP> and 41.2%, respectively, for IR3(<I>lacZ</I>) compared to 6150 ml L<SUP>−1</SUP>, 33.5 ml L<SUP>−1</SUP> h<SUP>−1</SUP> and 32.5%, respectively, for B10(<I>lacZ</I>).</P> <P><B>Highlights</B></P> <P> <UL> <LI> Recombinant <I>R. capsulatus</I> strains containing the <I>E. coli lacZ</I> gene were used. </LI> <LI> In the presence of lactate, lactose was efficiently hydrolyzed to monosaccharides. </LI> <LI> The glucose formed was partially converted to H<SUB>2</SUB> but galactose was not metabolized. </LI> <LI> H<SUB>2</SUB> production from lactose-lactate mixtures was modeled and optimized. </LI> <LI> Substrate concentrations used were in the range found in natural cheese whey. </LI> </UL> </P>