Figure 1.
The antibiotic resistance profiles of all the study bacteria from ten soils.
Isolates were individually screened for resistance to each of 23 antibiotics.
Figure 2.
Resistance spectrum of the bacterial soil isolates.
Antibiotic resistance was measured as growth on 20 µg/ml of antibiotic.
Table 1.
Geographical and descriptive characteristics of the analyzed soil samples.
Figure 3.
The antibiotic resistance profiles and percentage mediated by efflux of all the study bacteria.
The antibiotics are color coded according to class. The total bar is the percentage resistance of all isolates to each antibiotic. The lightly shaded bar is the percentage of resistance mediated by efflux for each antibiotic.
Figure 4.
The phylogenetic distribution and relatedness of the soil bacteria.
The 16S rRNA genes were sequenced from all bacteria and the phylogenetic tree was created using these sequences and the ARB program package. Branches of the tree are color coded by bacterial orders, with each line at the branch end representing an individual bacterial isolate. The orders with the largest number of lines indicate the largest number of bacterial members within this study. The relatedness of the orders is defined by the distance from one branch to the next. The unclassified bacteria are therefore, closest to the Pseudomonadales.
Table 2.
The variations in the intrinsomes of soil and clinical bacteria.
Table 3.
Genotypic screening of mobile antibiotic resistance genes in the bacterial isolates and extracted soil DNA.
Figure 5.
Enzyme inhibition assay using trimethoprim (20 µg/ml) and trimethoprim susceptible S. aureus ATCC 25923.
An agar plate section containing trimethoprim (20 µg/ml), was inoculated with trimethoprim susceptible S. aureus ATCC 25923. An agar plug containing the trimethoprim inhibiting soil bacteria were placed into the inoculated trimethoprim agar. The soil bacteria producing the enzyme inhibiting trimethoprim is located in the center circle (A). The ring of growth of trimethoprim susceptible S. aureus, which has been protected from the inhibitory effects of trimethoprim by the soil bacteria enzyme (B). There is no S. aureus growth outside the zone of trimethoprim inhibition by the soil bacteria (C).