and production of Azotobacter vinelandii? and
antifungal activity against Fusarium oxysporum
Bhosale*, T.A. Kadam and A.R. Bobade
of Microbiology, School of Life Sciences, Swami Ramanand Teerth Marathwada
University, Nanded-431 606 , India
Author email : firstname.lastname@example.org
07 September 2011
30 March 2012
26 May 2012
phytopathogenic Fusarium species are one of the leading causes of loss
in agricultural productivity. In search of an efficient bacterial antagonist,
19 soil isolates of Azotobacter sp. were screened for antagonistic
activity against Fusarium oxysporum by agar well diffusion assay. The
potential strain was identified as Azotobacter vinelandii by 16S rRNA
sequencing. Optimum conditions for culturing A. vinelandii to obtain
maximum antifungal activity were determined by varying temperature, pH,
incubation period and NaCl and sucrose concentration. Maximum inhibition of F.
oxysporum was observed at pH 7 and 8, 1% NaCl and 2% sucrose
concentration and after 72 hr of incubation at 30?C temperature. A.
vinelandii showed 44% higher yield of antifungal metabolite under
optimized conditions. The minimum inhibitory concentration was 10 ?g ml-1
for F. oxysporum. The FTIR analysis of purified metabolite showed
presence of aldehyde, C-N, ester, aromatic ring, P-H stretch, and C-N stretch
of alkyl amine in the structure. The purified antifungal metabolite of A.
vinelandii showed effect on spore germination and mycelia morphology of F.
oxysporum. The study revealed significance of A. vinelandii in
controlling F. oxysporum and its promising application as a biocontrol
agent in agriculture.
vinelandii, Antifungal metabolite, Fusarium oxysporum
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