الفهرس 
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Abstract
SUMMARY
Genus Pseudomonas has tremendous importance due to its widespread distribution in soil. This may be capable of utilizing a wide range of organic and inorganic compounds and of living under diverse environmental conditions. Consequently, they are ubiquitous in soil and water ecosystems and are important as plant, animal and human pathogens. The genus Pseudomonas is well known for its metabolic versatility and genetic plasticity. The species of Pseudomonas, in general, grow rapidly and are particularly renowned for their ability to metabolize an extensive number of substrates. Saprophytic fluorescent pseudomonas spp. consititute an oxidase positive group, including the species P.flourescences produced siderophores, which shown to express antifungal and antibacterial activity. Co-inoculation of the fluorescent pseudomonads and Rhizobium improved plant growth in terms of shoot height, root length and dry weight.
P.aeruginosa is a gram negative free living bacterium and an opportunistic pathogen that can inhabit environments including plants, soil, water and other moist locations. P.aeruginosa nowadays is commonly isolated from cases of nosocomial infections especially from compromised hosts, such as patients suffering from respiratory diseases, cancer, children and young adults with cystic fibrosis and burns. According to the National Nosocomial Infections Surveillance System, P. aeruginosa is the third most common pathogen associated with all hospital acquired infections, accounting for 10.1% of all nosocomial infections and is associated with a high mortality rate. One of the reasons for its increased virulence is its notable resistance to many currently.
In this study occurrence of viruses specific for Pseudomonas was detected in some clay and loamy solis by the spot test and three viruses (phages) specific for P. aeurginosa and P. fragi were isolated from soil cultivated with potato, bean and taro from Faculty of Agriculture farm, Ain Shams University, (Shoubra El-khima,Qalubia Governorate, Egypt)
The phages were isolated on the base of the differences between the plaque morphology. The phages were signed as pa, pf1 and pf2. Phage Pa infects P.aeurginosa and forming circular, plaques, about 1mm in diameter and without halo and phage pf1and pf2 infect P.fragi and forming clear plaques and about 2mm in diameter and with center. The isolated phages were propagated by the enrichement liquid method which gave particles with concentration of 1012 pfu/ml. Phages were purified and concentrated by differential centrifugation (alternative low and high speed centrifugation ).
Electron microscopy examination of the uranyl acetate 2% negatively stained preparations showed that pa phage is tailess and the other two viruses, pf1 and pf2 are tadpole shape (have head and tail). Pa virus had an isometric head about 100 nm. Pf1 virus had an isometric head about 65±2 nm and a long contractile tail about 150±2 nm and neck about 8±2 nm. Pf2 virus had also isometric head about 60 nm and had a long contractile tail about 130±2 nm with a neck about 8±2 nm. UV – light absorpation properties of viruses showed that phages pa, pf1 and pf2 contained nucliec acid more than protein.
P.aeruginosa and P.fragi phages infecte few strains of pseudomonas belong to its species, which means that they have narrow or limited host range.
P. fragi phages (pf1and pf2) were stable if they exposed to osmtic shock until 8M sodium chloride solution, but phage (pa) lost it´s activity completely in 8M sodium chloride solution. Ascorbic acid and formaldehyde showed a virucidal effect on pseudomonas phages. High concentrations of Ascorbic acid (0.2-0.16 and 0.12%) inactivated 100% of the phages.Concentration of (4.5%) of formaldehyde inhibited (pa, pf1and pf2) with rate of 100% but P. aeurginosa phage was more stable.
Protein analysis of phages by 12 % SDS – polyacrylamide gel electrophoresis releaved that phage pa had7 structural proteins with molecular weights known and extrapolated of 130, 62, 48, 30, 28, 22 and 18 KDa, while Pseudomonas fragi pf1 virus had11 structural proteins with molecular weights known and extrapolated of 130, 88, 76, 62, 48, 33, 30, 28, 26, 22 and 18 KDa and P. fragi pf2 virus had 11structural proteins with molecular weights known and extrapolated of 130, 88, 76, 62, 48, 33, 30, 28, 26, 22 and 18 KDa.
Phages (pf1 and pf2) have double stranded DNA with molecular weight of about 5260.96bp and 4895.1bp for pf1 and pf2 phages, respectively.
RAPD PCR analysis was used for differentiate between the three isolates, pa phage is ds.RNA, but phage pf1and pf2 were ds.DNA
In conclusion, three phages specific for P. aeurginosa and P. fragi were isolated from soil cultivated with potato, bean and taro. They have different morphotypes by which pa belonging to Cystoviridae and (pf1 and pf2) belonging to Myoviridae. Also, phages differed in their UV – light absorption properties, host range or lytic patteren and chemical composition properties.