The Effect of Soil Mediated Genetic Changes and Plasmid Curing on Growth Rates of Pseudomonas and Staphylococcus spp. Isolated from Different Soils

The study was carried out to investigate the effect of soil mediated genetic change on growth rate of bacterial isolates from soils collected from different environments. Soil samples were collected from different sites: cow dung contaminated area, poultry, mechanic workshop, river, farmland and garden soils. Physiochemical analysis, bacteria isolation and enumeration were carried out on the different soil samples. Growth rate was determined by the measurement of turbidity at 600 nm using UV/VIS spectrophotometer on all isolates from two selected species (Pseudomonas and Staphylococcus) because of their even distribution in the soil samples. Plasmid curing was carried out on the selected isolates using 1 ml of 10% Sodium Dodecyl Sulphate as the curing agent and the growth rate of the plasmid-cured isolates were investigated. The results obtained indicated that the soil samples varied in their physiochemical properties. There were differences in the growth rates of bacterial isolates from the different soils for both Pseudomonas and Staphylococcus spp. a comparison between growth rate of test bacteria isolates before and after plasmid curing also suggested that curing significantly affected the growth rate of the test organisms in some soil samples. The results from this study suggested that the soil environments from which the various bacterial isolates were obtained had effect on the genetics of the bacteria isolates. The future direction to this study is to perform a molecular profiling of the various isolates to determine species specificity and also test for their virulence.