초록
<P>H<SUB>2</SUB> has a great potential as an ecologically-clean, renewable and capable fuel. It can be mainly produced via hydrogenases (Hyd) by different bacteria, especially <I>Escherichia coli</I> and <I>Rhodobacter sphaeroides</I>. The operation direction and activity of multiple Hyd enzymes in <I>E. coli</I> during mixed-acid fermentation might determine H<SUB>2 </SUB>production; some metabolic cross-talk between Hyd enzymes is proposed. Manipulating the activity of different Hyd enzymes is an effective way to enhance H<SUB>2</SUB> production by <I>E. coli</I> in biotechnology. Moreover, a novel approach would be the use of glycerol as feedstock in fermentation processes leading to H<SUB>2</SUB> production. Mixed carbon (sugar and glycerol) utilization studies enlarge the kind of organic wastes used in biotechnology. During photo-fermentation under limited nitrogen conditions, H<SUB>2</SUB> production by <I>Rh. sphaeroides</I> is observed when carbon and nitrogen sources are supplemented. The relationship of H<SUB>2</SUB> production with H<SUP>+</SUP> transport across the membrane and membrane-associated ATPase activity is shown. On the other hand, combination of carbon sources (succinate, malate) with different nitrogen sources (yeast extract, glutamate, glycine) as well as different metal (Fe, Ni, Mg) ions might regulate H<SUB>2</SUB> production. All these can enhance H<SUB>2</SUB> production yield by<I> Rh. sphaeroides</I> in biotechnology Finally, two of these bacteria might be combined to develop and consequently to optimize two stages of H<SUB>2</SUB> production biotechnology with high efficiency transformation of different organic sources.</P>