Title Comparison of the Bacterial Community and Characterization of Plant Growth-Promoting Rhizobacteria from Different Genotypes of Chrysopogon zizanioides (L.) Roberty (Vetiver) Rhizospheres
Author Juliana Mendes Monteiro1, Renata Estebanez Vollu1, Marcia Reed Rodrigues Coelho1, Celuta Sales Alviano1, Arie Fitzgerald Blank2, and Lucy Seldin1*
Address 1Instituto de Microbiologia Prof. Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, CEP 21941-901, Brazil, 2Departamento de Engenharia Agronômica, Universidade Federal do Sergipe, SE, CEP 21941-590, Brazil
Bibliography Journal of Microbiology, 47(4),363-370, 2009,
Key Words Chrysopogon zizanioides, nifH gene, plant growth-promoting rhizobacteria, phosphate solubilization, siderophore and auxin production, vetiver
Abstract Molecular approaches [PCR-denaturing gradient gel electrophoresis (DGGE)] were used to determine whether three different vetiver (Chrysopogon zizanioides) genotypes, commercially used in Brazil and considered economically important over the world, select specific bacterial populations to coexist in their rhizospheres. DGGE profiles revealed that the predominant rhizospheric bacterial community hardly varies regarding the vetiver genotype. Moreover, using traditional cultivation methods, bacterial strains were isolated from the different rhizospheres. Colonies presenting different morphologies (83) were selected for determining their potential for plant growth promotion. More than half of the strains tested (57.8%) were amplified by PCR using nifH-based primers, specific for the enzyme nitrogenase reductase. The production of siderophores was observed in 88% of the strains, while the production of antimicrobial substances was detected in only 14.5% of the isolates when Micrococcus sp. was used as the indicator strain. Production of indole-3-acetic acid and the solubilization of phosphate were observed in 55.4% and 59% of the isolates, respectively. In total, 44 strains (53%) presented at least three characteristics of plant growth promotion and were submitted to amplified ribosomal DNA restriction analysis. Twenty-four genetic groups were formed at 100% similarity and one representative of each group was selected for their identification by partial 16S rRNA gene sequencing. They were affiliated with the genera Acinetobacter, Comamonas, Chryseobacterium, Klebsiella, Enterobacter, Pantoea, Dyella, Burkholderia, or Pseudomonas. These strains can be considered of great importance as possible biofertilizers in vetiver.