Journal of Pure and Applied MicrobiologyVol. 9 No. 1

In vitro Control of Fusarium oxysporum ATCC-48112TM and Aspergillus flavus ATCC-9643TM by Wheat Rhizospheric Pseudomonas fluorescens

Alghuthaymi, Mousa Abdullah

Department of Biology, Science and Humanities College, Alquwayiyah, Shaqra University, Saudi Arabia.

Received on 11 December 2014 and accepted on 10 January 2015

 

ABSTRACT

There 70 bacterial strains were isolated from the rhizosphere zone of wheat. All of them subjected to screening to exhibit an antifungal activity against two main phytopathogenic fungi; F. oxysporum ATCC-48112TM and A. flavus ATCC-9643TM. The screening test revealed that, 32 bacterial strains were found have an antifungal activity against both fungi mentioned before. There were 7 fluorescent strains observed under UV light. These fluorescent strains exhibited more antifungal activity than others. Nevertheless, one of them was the most potent antifungal fluorescent strain. Seven fluorescent strains were identified as P. fluorescens, which subjected to PCR to detect PhlD gene which responsible for 2,4-diacetylphloroglucinol (DAPG) production. P. fluorescens produced DNA fragments corresponding to approximately 745-bp size that corroborated with the predicted known PhlD sequence of Pf-5(NRRL B-23932) used as positive control in the current study. The antifungal compound was extracted from the suspension of P. fluorescens and then identified by using NMR and HPLC techniques. Eventually, there some physiological conditions were studied which impact on DAPG production such as oxygen percentage, temperature, sugars, amino acids.

Keywords : Aspergillus species, Fusarium oxysporum, King?s-B, Pseudomonas fluorescens and wheat rhizosphere.