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Plant Growth Promoting Characterization of Indigenous Azotobacteria Isolated from Soils in Iran

Plant Growth Promoting Characterization of Indigenous Azotobacteria Isolated from Soils in Iran It has been well known that the bacteria of the genus Azotobacter, in addition to the beneficial N2-fixing activity, are able to improve plant growth by a number of direct and indirect mechanisms. To identify this potential in indigenous azotobacteria, the efficiency of 17 isolates of Azotobacter from the rhizosphere of wheat and barley plants cultivated in salt- and/or drought-affected soils in Iran were evaluated for their ability to dissolve inorganic and organic phosphates, siderophore secretion, indole acetic acid (IAA) production; and protease, chitinase, and ACC deaminase (ACCD) activities. First, they were biochemically characterized and one isolate (strain) was identified by 16S rDNA sequencing. Eight isolates were designated as Azotobacter vinelandii and the remaining isolates were identified as A. chroococcum. All isolates hydrolyzed the organic and inorganic phosphate compounds and effectively produced IAA. Fifteen isolates produced siderophore, but only one isolate showed protease activity which is being reported for the first time in relation to Azotobacter. None of the 17 isolates was capable of producing ACCD or chitinase. However, polymerase chain reaction amplification of the ACCD coding genes, by the use of the gene-specific primers, indicated that not all contain the ACCD gene. The standard screening methods with slight modifications, especially in the case of ACCD assay, were applied. The results showed that the use of specific screening methods, modified according to bacterial nutritional requirements, are the efficient methods for precise evaluation of the plant growth promoting rhizobacteria activity. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Current Microbiology Springer Journals

Plant Growth Promoting Characterization of Indigenous Azotobacteria Isolated from Soils in Iran

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References (24)

Publisher
Springer Journals
Copyright
Copyright © 2012 by Springer Science+Business Media, LLC
Subject
Life Sciences; Biotechnology; Microbiology
ISSN
0343-8651
eISSN
1432-0991
DOI
10.1007/s00284-012-0083-x
pmid
22294493
Publisher site
See Article on Publisher Site

Abstract

It has been well known that the bacteria of the genus Azotobacter, in addition to the beneficial N2-fixing activity, are able to improve plant growth by a number of direct and indirect mechanisms. To identify this potential in indigenous azotobacteria, the efficiency of 17 isolates of Azotobacter from the rhizosphere of wheat and barley plants cultivated in salt- and/or drought-affected soils in Iran were evaluated for their ability to dissolve inorganic and organic phosphates, siderophore secretion, indole acetic acid (IAA) production; and protease, chitinase, and ACC deaminase (ACCD) activities. First, they were biochemically characterized and one isolate (strain) was identified by 16S rDNA sequencing. Eight isolates were designated as Azotobacter vinelandii and the remaining isolates were identified as A. chroococcum. All isolates hydrolyzed the organic and inorganic phosphate compounds and effectively produced IAA. Fifteen isolates produced siderophore, but only one isolate showed protease activity which is being reported for the first time in relation to Azotobacter. None of the 17 isolates was capable of producing ACCD or chitinase. However, polymerase chain reaction amplification of the ACCD coding genes, by the use of the gene-specific primers, indicated that not all contain the ACCD gene. The standard screening methods with slight modifications, especially in the case of ACCD assay, were applied. The results showed that the use of specific screening methods, modified according to bacterial nutritional requirements, are the efficient methods for precise evaluation of the plant growth promoting rhizobacteria activity.

Journal

Current MicrobiologySpringer Journals

Published: Feb 1, 2012

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