الفهرس 
REVIEW OF LITERATUREOnly 14 pages are availabe for public view
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Abstract
This study was conducted to control potato soft rot disease caused by Pectobacterium carotovorum subsp. carotovorum using some virulent viruses. Phages able to infect the soft rot pathogen Pectobacterium carotovorum subsp. carotovorum were isolated from potato cultivated soil samples collected at sites displaying specific symptoms and characterized in term of growth characteristics and morphology within Damietta and Dakahlia Governorates. Three phages, designated EccP1, EccP2 and EccP3, were isolated. The bacterial isolate EGY2, sensitive to three isolated phages was identified by morphological, cultural, physiological, biochemical and molecular techniques. BLASTN analysis of the 16S rRNA sequence revealed a 99% similarity to the 16S rRNA sequence of Pectobacterium carotovorum subsp. carotovorum in the GenBank database. Electron micrographs indicated that all phages had tails and thus belonged to the order Caudovirales. Furthermore, the phages were assigned three virus families (Myoviridae; Siphoviridae and Podoviridae) on the basis of their morphological features. EccP1 had long contractile tail characterized to the family Myoviridae. While, EccP2 had long non-contractile tails, consistent with family Siphoviridae. Finally, EccP3 had polygonal head and a short non-contractile tail which typical of the family Podovoridae Also, No lysogenic bacteria appeared, this indicates that the phages behave the lytic cycle and hence it can be used in biological control. Host range determination revealed that the phages were not capable to infecting any bacterial species except Pectobacterium carotovorum subsp. carotovorum. In this study, phage adsorption was slow, requiring about 35-45 min to give maximum phage adsorption ranged from 64.15% to 80.17%. One step growth experiment showed that the latent periods, the rise periods and the brust sizes were ranged from 84-100 min, 59-73 min and 55-68 PFU/cell, respectively. The physical stability of these phages was also investigated. The results showed that the phages were approximately did not affected by elevating the temperature till 70°C, all isolates had the same DEP (10-5); LIV ranged from 40-44 h and the optimum pH value was 9. Furthermore, these phages were almost stable in range of pH 3.6 and pH 10. These phages contain a nucleic acid (DNA) with molecular weight of about 39, 40.59 and 39.5 Kpb, respectively. By studying the efficacy of using the isolated phages in controlling of soft rot disease, it is found that a cocktail of all three phages had the ability to decrease the soft rot severity with about 97%.