Detection of enterotoxigenic Escherichia coli in water by filter hybridization with three enterotoxin gene probes

mentioning

confidence: 99%

Lack of virulence factors in Escherichia coli strains of enteropathogenic serogroups isolated from water

Valentini

Gomes

Falcão

1992

“…(9) and Yersinia enterocolitica (12,14) from foods. Recently, this approach has been used for the detection of metal ion resistance (2), enterotoxigenic E. coli in water (8), catabolic genotypes in activated sludge (5), groundwater aquifer (15,22,28), and the soil microcosm (13), tracking of genetically engineered bacteria (1), and identification of bacteria in the environment (22,28).…”

mentioning

confidence: 99%

Construction and applications of DNA probes for detection of polychlorinated biphenyl-degrading genotypes in toxic organic-contaminated soil environments

Walia

Khan

Rosenthal

1990

DNA probes for polychlorinated biphenyl (PCB)-degrading genotypes were constructed from PCB-degrading bacteria. These laboratory-engineered DNA probes were used for the detection, enumeration, and isolation of specific bacteria degrading PCBs. Dot blot analysis of purified DNA from toxic organic chemical-contaminated soil bacterial communities showed positive DNA-DNA hybridization with a 32P-labeled DNA probe (pAW6194, cbpABCD). Less than 1% of bacterial colonies isolated from garden topsoil and >80 % of bacteria isolated from PCB-contaminated soils showed DNA homologies with 32P-labeled DNA probes. Some of the PCB-degrading bacterial isolates detected by the DNA probe method did not show biphenyl clearance. The DNA probe method was found to detect additional organisms with greater genetic potential to degrade PCBs than the biphenyl clearance method did. Results from this study demonstrate the usefulness of DNA probes in detecting specific PCB-degrading bacteria, abundance of PCB-degrading genotypes, and genotypic diversity among PCB-degrading bacteria in toxic chemical-polluted soil environments. We suggest that the DNA probe should be used with caution for accurate assessment of PCB-degradative capacity within soils and further recommend that a combination of DNA probe and biodegradation assay be used to determine the abundance of PCB-degrading bacteria in the soil bacterial community.

“…The utilization of DNA-DNA hybridization for the detection of specific DNA sequences in bacteria isolated from natural samples has been previously described. However, these studies were mostly concerned with the detection of pathogenic microorganisms in foods (16,24) and waters (14). The preparation of the mer gene probe described in this paper was aimed at the development of a means for the study of genetic change mechanisms in the adaptation of natural bacterial communities to a stressor.…”

Section: Discussionmentioning

confidence: 99%

Preparation of a DNA gene probe for detection of mercury resistance genes in gram-negative bacterial communities

Barkay¹,

Fouts²,

Olson³

1985

A DNA gene probe was prepared to study genetic change mechanisms responsible for adaptation to mercury in natural bacterial communities. The probe was constructed from a 2.6-kilobase NcoI-EcoRI DNA restriction fragment which spans the majority of the mercury resistance operon (mer) in the R-factor R100. The range of specificity of this gene probe was defined by hybridization to the DNA of a wide variety of mercury-resistant bacteria previously shown to possess the mercuric reductase enzyme. All of the tested gram-negative bacteria had DNA sequences homologous to the mer probe, whereas no such homologies were detected in DNA of the gram-positive strains, Thus, the mer probe can be utilized to study gene flow processes in gram-negative bacterial communities.