Assessment of 16S rRNA gene-based phylogenetic diversity and promising plant growth-promoting traits of Acinetobacter community from the rhizosphere of wheat

Strains belonging to the genus Acinetobacter and their plant growth-promoting properties have been reported in the literature. However, there is a paucity of information on the diversity of Acinetobacter species associated with the wheat rhizosphere. In the present investigation, Acinetobacter species diversity was assessed in the rhizosphere of wheat from three agricultural fields where different varieties were cultivated. The Acinetobacter species diversity was assessed by DGGE (Denaturing Gradient Gel Electrophoresis) of 16S rRNA gene PCR products amplified from total soil DNA using genus-specific primers. Ac. calcoaceticus, Ac. baumannii, Ac. lwoffii, Ac. baylyi and Acinetobacter sp. were detected in the rhizosphere of wheat. Prevalence of Acinetobacter species in the rhizosphere of wheat was also investigated by a cultivation-dependent approach. Ac. calcoaceticus, Ac. baumannii, Ac. lwoffii and Acinetobacter sp. were isolated on selective media from the same samples. In vitro characterization of Acinetobacter isolates revealed that majority of these bacteria exhibited plant growth-promoting traits such as nitrogen fixation, siderophore production and mineral solubilization. These Acinetobacter strains may play a favorable role in plant growth promotion while residing in the rhizosphere of wheat. (C) 2009 Elsevier GmbH. All rights reserved.