Evaluation and improvement of the energy efficiency of nitrogen fixation in Lotus corniculatus nodules induced by Rhizobium loti strains indigenous to Uruguay

被引:11
作者
Monza, J
Diaz, P
Borsani, O
RuizArgueso, T
Palacios, JM
机构
[1] UNIV POLITECN MADRID,ESCUELA TECH SUPER INGN AGRON,MICROBIOL LAB,E-28040 MADRID,SPAIN
[2] UNIV REPUBLICA,FAC AGRON,DEPT BIOQUIM,MONTEVIDEO 11600,URUGUAY
关键词
energy efficiency; hydrogenase; Lotus sp; Rhizobium loti;
D O I
10.1023/A:1018573527503
中图分类号
Q81 [生物工程学(生物技术)]; Q93 [微生物学];
学科分类号
071005 ; 0836 ; 090102 ; 100705 ;
摘要
In order to evaluate energy efficiency of nitrogen fixation by the Lotos corniculatus/Rhizobium loti symbiosis, Uruguayan R. loti strains were tested for hydrogen-uptake (Hup) status. Nodules induced in L. corniculatus by all eight R. loti strains tested evolved high amounts of hydrogen (2.0-8.7 mu mol H-2/h.g nodule fresh weight). This production of hydrogen corresponds to 38-69% of total nitrogenase activity estimated as acetylene reduction, suggesting that hydrogen is not recycled within these nodules. This was confirmed by the lack of hydrogenase activity in bacteroid suspensions. Additionally, no hybridization signals were observed in total DNA restriction digests from these strains when a DNA fragment containing part of hydrogenase structural genes from Rhizobium leguminosarum by. viciae was used as probe. Cosmid pHU52, containing the complete gene cluster required for hydrogen oxidation in Bradyrhizobium japonicum, was introduced into two X. loti strains. Transconjugants from only one of the strains were able to express hydrogenase activity in Vegetative cells incubated under the derepression conditions described for B. japonicum. Bacteroids induced by both transconjugant strains in L. corniculatus and Lotus tennis expressed hydrogenase activity in nodules. The level of hydrogenase activity induced in L. tennis nodules was two-fold higher than those induced in L. corniculatus. This implies the existence of a strong host effect on hydrogenase expression in this symbiotic system.
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页码:565 / 571
页数:7
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