Detection of multidrug-resistant Pseudomonas isolates and distribution of denitrifying functional genes

The aim of this study was to characterize 59 Pseudomonas strains isolated from soil samples in terms of Inducible Beta-Lactamase (IBL), fluorescence production, antibiotic resistance, presence of plasmids and genetic diversity, as well as denitrification functional genes. Fourteen out of fifty-nine (23.7%) Pseudomonas isolates were identified as multidrug-resistant. To evaluate the contribution of denitrification functional genes to genetic diversity, PCR products were screened by RFLP. It was determined that the 18, 6 and 22 out of 59 isolate harbored nirS, nirK and nosZ genes, respectively. It was found that the 37 isolates were nosZ-negative. Thus, these results suggest that nosZ gene-missing pseudomonad denitrifiers are partly contribute to N₂O emission. Moreover, nirS, nirK and nosZ genes were found to be positive with IBL and negatively correlated with fluorescence production. These results suggest that Pseudomonas species have important roles in soil and even in biosphere due to their diversity and genetic factors.