Mechanisms of isolated hydrogen-oxidizing bacteria in plant growth promotion and effects of hydrogen metabolism on rhizobacterial community structure

Abstract

Previous studies have showed that the hydrogen gas evolved from Hup - legume nodules promotes plant growth and increases the hydrogen uptake rate of soils adjacent to Hup - nodules. This may be resulted from hydrogen-induced variation of rhizobacterial community structure. Twenty isolates of hydrogen-oxidizing bacteria belonging to genera of Variovorax, Burkhorderia and Flavobacterium showed positive effect on root elongation.

This study showed that isolates belonging to Variovorax and Flavobacterium had ACC deaminase activity and isolates belonging to Burkhorderia had the ability to excrete rhizobitoxine or its structural analogue such as AVG, which meant that they have the ability to promote plant growth by lowering of plant ethylene levels. TRFLP studies showed that hydrogen metabolism resulted in obvious variation of bacterial community structure in hydrogen treated soils compared to the controls. TRF peaks whose intensity increased obviously in profiles from hydrogen-treated soils were possibly contributed by bacteria utilizing hydrogen gas.