Reversible oxygen‐tolerant hydrogenase carried by free‐living N2‐fixing bacteria isolated from the rhizospheres of rice, maize, and wheat

MicrobiologyOpen

Philippe Roumagnac¹  Pierre Richaud²  Mohamed Barakat³  Philippe Ortet³  Marie-Anne Roncato³  Thierry Heulin³  Gilles Peltier²  Wafa Achouak³ 

[1] CIRAD, UMR BGPI, Campus International de Montferrier-Baillarguet, Montpellier Cedex-5, France;CNRS, UMR 6191, Biologie Végétale et Microbiologie Environnementales, Saint-Paul-lez-Durance, France;CEA, DSV, IBEB, Laboratoire d'écologie microbienne de la rhizosphère et d'environnements extrêmes, Centre de Cadarache, Saint-Paul-lez-Durance, France

关键词: Diversity;    engineering;    hydrogen metabolism;    hydrogenase;    oxygen;   

DOI  :  10.1002/mbo3.37

来源: Wiley

【 摘 要 】

Abstract

Hydrogen production by microorganisms is often described as a promising sustainable and clean energy source, but still faces several obstacles, which prevent practical application. Among them, oxygen sensitivity of hydrogenases represents one of the major limitations hampering the biotechnological implementation of photobiological production processes. Here, we describe a hierarchical biodiversity-based approach, including a chemochromic screening of hydrogenase activity of hundreds of bacterial strains collected from several ecosystems, followed by mass spectrometry measurements of hydrogenase activity of a selection of the H₂-oxidizing bacterial strains identified during the screen. In all, 131 of 1266 strains, isolated from cereal rhizospheres and basins containing irradiating waste, were scored as H₂-oxidizing bacteria, including Pseudomonas sp., Serratia sp., Stenotrophomonas sp., Enterobacter sp., Rahnella sp., Burkholderia sp., and Ralstonia sp. isolates. Four free-living N₂-fixing bacteria harbored a high and oxygen-tolerant hydrogenase activity, which was not fully inhibited within entire cells up to 150–250 μmol/L O₂ concentration or within soluble protein extracts up to 25–30 μmol/L. The only hydrogenase-related genes that we could reveal in these strains were of the hyc type (subunits of formate hydrogenlyase complex). The four free-living N₂-fixing bacteria were closely related to Enterobacter radicincitans based on the sequences of four genes (16S rRNA, rpoB, hsp60, and hycE genes). These results should bring interesting prospects for microbial biohydrogen production and might have ecophysiological significance for bacterial adaptation to the oxic–anoxic interfaces in the rhizosphere.

【 授权许可】

CC BY-NC   
© 2012 The Authors. MicrobiologyOpen published by Blackwell Publishing Ltd.

Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.