Use of Repetitive DNA Sequences and the PCR to Identify Fecal Escherichia coli Isolates from Different Soils

Microbial communities which inhabit the soil environment are large and diverse. Because of the tight relationship between microbial activity and soil functioning and the reality that microorganisms are sensitive and respond quickly to changes in soil conditions. Fecal coliforms normally inhibited the intestinal tract of warm-blooded animals. Outside of a warm-blooded host, fecal coliforms are short-lived in comparison with the coliform bacteria that are free-living and not associated with the digestive tract of man or animals. Gram negative microorganisms have been reported to be capable of utilizing a wide variety of hydrocarbons as carbon and energy source such as E. coli. The aims of present study are the Isolation and identification of Escherichia coli isolates from (Hydrocarbons& Sewage) contaminated soils. In this paper six soil samples (Contaminated with Hydrocarbons, Sewages and control) were collected from different regions in Baghdad City. And a total of 57 bacterial isolates were isolated from these soils that belong to Escherichia species by making Gram staining, cultured on MacConkey and EMB agar to observe the colony morphology, biochemical tests were used in the identification of bacteria included (Thermotolerant (faecal) Coliform test, Indole test, Methyl red test, Voges Proskauer test, Citrate utilization test, Motility test), And because of E. coli is highly diverse at the genotypic level as well. This High genotypic diversity has been identified in E. coli based on the repetitive extragenic palindromic PCR (rep-PCR) DNA fingerprinting (BOX-PCR). This technique can reveal the alteration of microbial genome structures and evolution of microbial genomes. The result shows a lot of genetic variation among isolates from the same and different soils. This lead to the possibility of using the E. coli as indicator organism and because of the tight relationship between the status of microorganism and soil functioning, and also the fact that microorganisms respond quicker to changes in soil environment, E. coli is important to early detect and assess changes in soil status, in order to determine the direction of that change.