الفهرس 
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Abstract
Actinomycetes are considered one of the most important bioactive metabolites procedures especially the genus Streptomyces. This study involves the isolation and comparison between different isolates (from Damietta) belonging to the genus Streptomyces that have the ability of production of some antifungal compounds.
The outcome of this study can be summarized as follow:
1- Isolation of actinomycetes from soils
We isolated fourteen actinomycetes from different sources sites from soil in Damietta. Nine isolates had white colour and five isolates were grey to light grey colour. All the isolates had powdery appearance on starch- nitrate agar media except M7 had leathery appearance.
2- screening of actinomyctes for antifungal activities
During primary and secondary screening, there were some of tested actinomycetes showed antifungal activity against some phyto pathogenic fungi Penicillium chrysogenum, P. italicum., Macrophomina phaseolina, Fusarium oxysporium, F. solani, Alternaria alternata, Sclerotina sclerotiorum and Rhizoctonia solani. The results showed that actinomycetes isolates coded O5, Gnl1,8F and M7 have showed good antifungal activity against tested phyto pathogenic fungi. The isolates O5 and M7 could inhibit the growth of some tested fungi, the strongest inhibition zones were obtained against Alternaria alternata and Macrophomina phaseolina. The isolates La5, 8F and Gnl1 had a moderate antifungal activity against some tested phyto pathogenic fungi. The most affected phyto pathogenic fungi by actinomycetes isolates are Macrophomina phaseolina and Alternaria alternata. So, we selected the actinomycetes isolates O5 and M7 for further work against Macrophomina phaseolina and Alternaria alternata.
3- characterization and identification of the most active isolates
The detailed comparative studies of the most two active isolates were done by using combination of the traditional classification (i.e. cultural, morphological and physiological properties) and molecular classification. According to the results of these studies, the isolates are closely related and identified as following:
Streptomyces flavovirens and Streptomyces gougeroti
4- factors affecting the antifungal activity produced by Streptomyces flavovirens and Streptomyces gougeroti
Streptomyces flavovirens and Streptomyces gougerotii were selected for further study according to their high potential abilities against the tested phyto pathogenic fungi.
Optimization for antifungal activities by Streptomyces flavovirens and Streptomyces gougeroti showed that:
• glycerol-yeast extract broth medium, pH: 6.5 were optimal for promoting antifungal activities of both isolates.
Four and five days incubation period showed high antifungal activites by Streptomyces flavovirens and Streptomyces gougeroti respectively.
• 30 °C and 35 °C were suitable for Streptomyces flavovirens and Streptomyces gougeroiti respectively to produce antifungal activites.
• Glycerol was the best carbon sources for both isolates.
• Tryptone and beef extract were the best nitrogen sources for Streptomyces flavovirens and Streptomyces gougeroti respectively to produce antifungal activities.
According to these results, Streptomyces flavovirens isolate produced the strongest antifungal agents towards tested phytopathogenic fungi. So, the antifungal agents of Streptomyces flavovirens isolate was extracted for further characterization and identification
5- selection of the best solvent for extracting antifungal compounds from Streptomyces flavovirens
Chloroform, petroleum ether and ethyl acetate solvents were used for extraction of the antifungal compounds from Streptomyces flavovirens. The bioactivity of each extract was tested against the tested phytopathogenic fungi Macrophomina phaseolina and Alternaria alternata.
6- Extraction and characterization of the bioactive metabolite of Streptomyces flavovirens
Solvent extraction method was done to isolate the active substances from the supernatant of Streptomyces flavovirens. Chloroform and ethyl acetate solvents succeeded to extract the active substances. Separation of antifungal compounds was done by using TLC. Identification of antifungal compounds was done by using GC/MS that detected 16 compound. 8 compounds were extracted by chloroform and 8 compounds were extracted by ethyl acetate, only 8 compounds showed biological activities according to previous researches. These active compounds are:
Bis(2-ethylhexyl) isophthalate
1,4-Benzenedicarboxylic acid, bis(2-ethylhexyl) ester
Astaxanthin
psi.,.psi.-Carotene, 1,1’,2,2’- tetrahydro-1,1’-dimethoxy-
Lycopene
1-Monolinoleoylglycerol trimethylsilyl ether
7,9-Di-tert-butyl-1-oxaspiro(4,5)deca-6,9-diene-2,8-dione
1H-Cyclopropa[3,4]benz[1,2-e]azulene-5,7b,9,9a-tetrol.