Characterization of bacterial soft rot strains and their specific phages isolated from soil at taif

In this study some bacteriophage(s) specific to some plant pathogenic bacteria (the causal agent of soft rot diseases),were isolated and characterized from soil of taif,ksa. soil samples were randomly collected from some rhizosphere soils cultivated with various plant species including potato. ten bacterial isolates were obtained from soil and used as hosts for enrichment and isolation of the virulent bacteriophages. the spot test and turbidity tests were used to detect the presence of the phage of interest in the suspension. the area of clear zones were represented by threes levels,i.e.,weak lysis (+) (three isolates),moderate lysis (++) (one isolate) and high lysis (+++) (two isolates). the phage(s) was propagated and partially purified for determining the morphology of viral particles via electron microscopy. sperm shape virus-like particles with long tail and icosahedral head were shown in the electron micrographs of partially purified phages specific to the two selected bacterial isolates (# 08 and # 10). these two bacterial isolates were then biologically and molecularly identified. the nucleotide sequences of 16s rrna gene of the two bacterial isolates was determined and final sequences of 942 and 940 nts for the 16s rrna gene of two soft rot bacteria (# 08 and # 10),respectively were recorded. data of the phylogentic trees show that the two bacterial isolates (# 08 and # 10) could be strains of pseudomonas stutzeri (lc053456.1) and bacillus pumilus (lc053854.1).