Journal of Pure and Applied MicrobiologyVol. 8 No. 2

Physiological Characteristics and Phylogeny of Hydrogen-Oxidizing Bacteria in Medicago sativa Rhizosphere with Plant Growth Promoting Mechanism

Bo Fu1, 2, Zhongling Li2, Xin Guo1, Bentao Xiong1, Xingdu Chen3 and Weiwei Wang1*

1Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, Northwest University, Xi? an - 710 069, China. 2Institute of Enzyme Engineering, Shaanxi Academy of Sciences, Xi?an - 710 600, China. 3School of Environment and Municipal Engineering, Xi?an University of Architecture and Technology, Xi?an - 710 055, China.

Received on 09 January 2014 and accepted on 18 March 2014

 

ABSTRACT

A gas-cycle incubation system (H2 treatment system) and mineral salt agar medium was used to isolate and culture hydrogen-oxidizing bacteria in Medicago sativa rhizosphere, and 37 strains were finally isolated and cultured, 8 strains of which could absorb H2 more than 2.44?10-4 mol/L was identified as Pseudomonas sp., Plesiomonas sp., Pimelobacter sp., Xanthobacter sp., Leminorella sp., Terrabacter sp., Rarobacte sp. according to the cell, colony form and biochemical characteristics. The heterotrophy culture condition of strain WMQ-7 was also studied. The enzyme activity of strain WMQ-7 was 0.671 U/?g and the content of siderophore produced by strain WMQ-7 was 7.1996 ?g/mL. 16S rDNA sequence of strain WMQ-7, FMG-3, FMG-5 was analyzed and built the phylogenic tree. From the physiology characteristic and inherited characteristic, strain WMQ-7 was finally identified as Pseudomonas putida (GenBank accession number EU807744). Stain FMG-5 was 94 % similar to the Rhizobium etli, while the 16S rDNA sequence of strain FMG-3 could not find a similar comparison in GenBank. In the experiments of the 8 hydrogen-oxidizing bacteria effect on wheat, the results showed that strain WMQ-7, FMG-3 and FMG-5 had strong ability to promote the growth of wheat. It is possible that the plant growth promoting mechanism of strain WMQ-7 was due to its ACC deaminase activity and the siderophore.

Keywords : Medicago sativa, Hydrogen-Oxidizing Bacteria, Siderophore.