초록
<P><B>Abstract</B></P> <P>Fe<SUP>0</SUP> and Ni<SUP>0</SUP> nanoparticles (NPs) of certain size were synthesized and added to the hydrogen production system from cotton stalk hydrolysate using <I>Klebsiella</I> sp. WL1316. Fe<SUP>0</SUP> and Ni<SUP>0</SUP> NPs with a size of 50 nm at all concentrations effectively improve hydrogen production during mid to late fermentation stages; particularly, the highest daily hydrogen production obtained following treatment with 50 nm Fe<SUP>0</SUP> NPs at 30 mg/L fermented for 96 h significantly increased by 61% comparing to the control treatment. The reducing sugar consumption in cotton stalk hydrolysate and ΔOD<SUB>600</SUB> could be improved to some extent by Fe<SUP>0</SUP> and Ni<SUP>0</SUP> NPs supplementation. Addition of Fe<SUP>0</SUP> or Ni<SUP>0</SUP> NPs of 50 nm at a concentration of 30 mg/L resulted in enhanced cumulative hydrogen production with improvement of hydrogen yield reached higher than 20%, and the values of Y(H<SUB>2</SUB>/S) were all higher than 90 mL/g <SUB>substrate</SUB>, reflecting good hydrogen production and substrate consumption. The analysis of the main soluble metabolites profile revealed that supplementation with Fe<SUP>0</SUP> and Ni<SUP>0</SUP> NPs of suitable size and concentration may decrease the metabolic flux in the competitive branch of hydrogen production and increase the metabolic flux of the key node that leads to hydrogen generation, thus promoting biohydrogen synthesis.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Fe<SUP>0</SUP> and Ni<SUP>0</SUP> NPs with suitable size and concentration enhanced hydrogen production. </LI> <LI> Suitable Fe<SUP>0</SUP> and Ni<SUP>0</SUP> NPs addition improved sugar consumption and bacterial growth. </LI> <LI> Emphasize NP size effect on enhancement of hydrogen production for the first time. </LI> <LI> Daily hydrogen production increased by 61% upon optimum Fe<SUP>0</SUP> NPs addition at 96 h. </LI> <LI> Hydrogen yield enhanced higher than 20% upon optimum Fe<SUP>0</SUP> and Ni<SUP>0</SUP> NPs addition. </LI> </UL> </P>