Agron. Sustain. Dev. 26 (2006) 143-150
DOI: 10.1051/agro:2006007

Plant growth-promoting bacteria as biofertilizer

Fauzia Y. Hafeez^a, Sumera Yasmin^a, Dini Ariani^b, Mehboob-ur-Rahman^a, Yusuf Zafar^a and Kauser A. Malik<sup>a

a</sup>  National Institute for Biotechnology and Genetic Engineering (NIBGE), PO Box 577, Jhang Road, Faisalabad 38000, Pakistan
^b  R&D Centre for Biotechnology, The Indonesian Institute of Sciences, JI. Raya Bogor Km 46, Cibinong 16911, Indonesia

(Accepted 18 May 2006; published online 8 July 2006)

Abstract - Seventeen rhizobacteria isolated from different ecological regions, i.e. Brazil, Indonesia, Mongolia and Pakistan were studied to develop inoculants for wheat, maize and rice. Almost all the bacterial isolates were Gram-negative, fast-growing motile rods and utilized a wide range of carbon sources. These isolates produced indole-3-acetic acid at concentrations ranging from 0.8-42.1 µg/mL, irrespective of the region. Fifteen isolates fixed N at rates ranging from 20.3-556.8 nmole C₂H₂ reduced/h/vial. Isolate 8N-4 from Mongolia produced the highest amount of indole-3-acetic acid (42.1 µg/mL), produced siderophores (0.3 mg/mL) and was the only isolate that solubilized phosphate (188.7 µg P/mL). Inoculation of the wheat variety Orkhon with 8N-4 isolate resulted in the maximum increase in plant biomass, root length, and total N and P contents in plants. Random amplified polymorphic deoxyribonucleic acid (RAPD) analysis, conducted with 60 decamer primers, revealed a high level of polymorphism among the bacterial isolates from different geographic regions and a low level of polymorphism among isolates from the same region. The complete 16S rRNA gene sequence analysis demonstrated that 8N-4 is a Bacillus pumilus strain (Accession number AY548949). It was concluded that Bacillus pumilus 8N-4 can be used as a bio-inoculant for biofertilizer production to increase the crop yield of wheat variety Orkhon in Mongolia.

Key words: Rhizobacteria / genetic diversity / RAPD

Corresponding author: Fauzia Y. Hafeez fauzia_y@yahoo.com

© INRA, EDP Sciences 2006