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by
Elsayed B. Belal |
Total Records (
1 ) for
Elsayed B. Belal |
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Elsayed B. Belal
,
S.M.H. Kamel
and
M.M. Hassan
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The present investigation was carried out to produce of antimicrobial
metabolites by Bacillus subtilis during two successive seasons 2011/2012.
One bacterial strain was isolated from healthy leaves of infected cucumber plants
with Pseudoperonospora cubensis or Sphaerotheca fuliginea. Spraying
of cucumber plants was done with bioagent (108 CFU mL-1)
under greenhouse conditions as protective treatment comparing with fungicides.
The obtained results exhibited that all treatments reduced the disease severity
comparing with control. The microbial bioagent was identified by using 16S rDNA
sequencing technique as Bacillus subtilis. The maximum accumulation of
metabolites occurred at the stationary phase. Metabolites accumulation coincided
with increase in the specific growth rate and reduction of disease severity.
Maximum activity of metabolites was at pH 7 and 30°C. Mode of metabolites
action on (sporangiophore and sporaniga) of P. cubensis and (conidiophore
and conidia) of S. fuliginea by examination of Scanning Electron Microscope
and their identification by GC-MS was investigated. It was observed that collapse
in sporangiophore, sporangia and conidia. These compounds mostly included fatty
acids known as Hexadecanoic acid, n-Hexadecanoic acid, Octadecanoic acid, 8-Octadecanoic
acid, 9-Octadecanoic acid, Pentadecanoic acid, Heptadecanoic acid, dodecatrienoic
acid, Nonanoic acid and Decanoic acid. Sprayed plants recorded best results
for peroxidase and polyphenol oxidase enzymes activity compared with unsprayed
one. Antibiotics exhibited also antagonistic activity against of Staphylococcus
aureus by inhibition zone formation. In conclusion, bioagent can be use
as an alternative and safe method to fungicides in controlling downy and powdery
mildew diseases of cucumber and inhibition of Staphylococcus aureus as
pathogenic bacteria. |
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