Peters G A, Evans W R, Toia R E
Charles F. Kettering Research Laboratory, Yellow Springs, Ohio 45387.
Plant Physiol. 1976 Aug;58(2):119-26. doi: 10.1104/pp.58.2.119.
The water fern, Azolla caroliniana Willd., containing the symbiotic, heterocystous blue-green alga, Anabaena azollae, has been studied under various growth conditions to characterize its light-dependent production of H(2). The response of H(2) production to N(2) and C(2)H(2) and the absence of a differential effect of m-chlorocarbonyl cyanide phenylhydrazone on H(2) production and C(2)H(2) reduction, coupled with the parallel inhibition of both processes by DCMU imply that the production of H(2) is nitrogenase-catalyzed and ATP-dependent.H(2) was produced by fronds grown under air-CO(2) in the presence or absence of combined nitrogen. When cultured under argon-O(2)-CO(2), only those fronds provided with combined nitrogen remained viable and produced H(2). Fronds grown on nitrate under air plus 2% CO also produced H(2). In comparison to fronds grown on N(2) alone, fronds grown on nitrate had an increased rate of H(2) production relative to C(2)H(2) reduction, and the inhibition of H(2) production by air was less.CO in argon +/- CO(2) resulted in a partial inhibition of H(2) production, whereas CO in argon-CO(2)-C(2)H(2) enhanced H(2) production in fronds grown without combined nitrogen. Our studies strongly indicate that H(2) production is nitrogenase-catalyzed but the possibility that the symbiont contains a hydrogenase cannot be totally excluded.
满江红（Azolla caroliniana Willd.）含有共生的、具异形胞的蓝藻鱼腥藻（Anabaena azollae），人们已在各种生长条件下对其进行研究，以表征其光依赖型氢气产生过程。氢气产生对氮气和乙炔的响应，以及间氯羰基氰化物苯腙对氢气产生和乙炔还原没有差异效应，再加上二氯苯基二甲基脲对这两个过程的平行抑制，这表明氢气的产生是由固氮酶催化且依赖于ATP的。在有或没有化合态氮存在的情况下，在空气 - 二氧化碳环境中生长的叶片都会产生氢气。当在氩气 - 氧气 - 二氧化碳环境中培养时，只有那些供应了化合态氮的叶片仍能存活并产生氢气。在空气加2%二氧化碳条件下以硝酸盐为培养基生长的叶片也会产生氢气。与仅在氮气环境中生长的叶片相比，以硝酸盐为培养基生长的叶片相对于乙炔还原而言，氢气产生速率更高，并且空气对氢气产生的抑制作用更小。氩气中的一氧化碳+/-二氧化碳会导致氢气产生受到部分抑制，而在氩气 - 二氧化碳 - 乙炔环境中的一氧化碳则会增强在没有化合态氮的情况下生长的叶片的氢气产生。我们的研究强烈表明氢气产生是由固氮酶催化的，但不能完全排除共生体中含有氢化酶的可能性。
