Abundance and Variation of Virulence of Rhizobiophages Isolated from the Rhizosphere of Some Legume Plants in Egypt
Abundance and Variation of Virulence of Rhizobiophages Isolated from the Rhizosphere of Some Legume Plants in Egypt
Ramy A. Qabel1; Tarek F. El-Arabi2; Adel A. Shoukry1; Hassan H. Elsebaay1; Abdel-Aziz F. El-Hamahmy1
ABSTRACT
The efficiency of Rhizobium bacteria to form a successful symbiosis with legume plants is governed by many factors. The foremost factor that could affect the rhizobia is bacteriophage infection. In this context, this study aimed to investigate the abundance of rhizobiophages in Egypt. Rhizobiophages were isolated from the rhizosphere of different legume plants. While no temperate phages were detected, two groups of phages were determined based on their virulence. Highly virulent phages designated as group V showed clear plaques and were able to infect many of Rhizobium species and strains. The other group of phages was less virulent and showed turbid plaques implied as group L. This was also determined by one-step growth experiment. It was found that rhizobiophage (V) group had the attachment and latent period after 30 min and burst size of 28. On the other hand, rhizobiophages (L) group had the attachment and latent period after 20 min and burst size of 9. The Group L even though they had low adsorption capacity of 59.4% after 30 min while group V was 91.6% after 30 min, they had higher adsorption velocity at 1.06×10-10 and 9.99×10-11 after 10 and 20 min while it was 5.24×10-9 and 1.25×10-10, after 20 and 30 min, respectively for group V. Electron micrographs of the isolated phages showed that they were belonging to two different morphological families; Myoviridae with isometric heads and contractile tails and Podoviridae with elongated heads and short tails. It can be concluded that the rhizospheres of legume plants contain high level of phage dynamics that can work in the favor of rhizobia.
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