Figure 5. A picture showing PCR amplification of 16 S rRNA on an agarose gel. Lane 1
DNA ladder; Lane 2 negative control; Lane 3-9 sample PCR isolates 1-7
(the amplified band size is 1600 bp)
DISSCUSSIONS
There were 14 rhizobacteria isolates recovered from both asymptomatic and symptomatic infected wide varieties of lettuces, i.e., green oak, red oak, cos, and butter head. When they were identified, it was found that all isolates were rhizobacteria where Serratia was the dominant species. This result supported the study of Mohamed et al. (2009), who found that Serratia was one of bacterial major group in root-knot diseases.
It was shown that the rhizobacteria isolates that had highest inhibitory capabilities were fallen in the genus Serratia. This finding was in agreement with the study of Daayf et al. (2003), who found that bacteria in the genera of Bacillus, Pseudomonas, Rahnella, and Serratia showed inhibitory capability in both directly and indirectly antibiosis, which was the induction factor of plant defense systems. Idris et al. (2008) found that S. marcescens No.2 caused 80.37% reduction against the growth of Fusarium