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Microbiology.

Antimicrobial Effects of Thieves Oil and its Components. Ali Iceman, Veronica Riha, and Margaret M. Gorman, Madonna University

This study focused on thieves oil as an antimicrobial agent. Minimal Inhibitory Concentrations (MIC) were done using thieves oil against normal skin flora and E. coli. Along with MICs of thieves oil, the components of thieves oil were also tested. This included; clove oil, cinnamon oil, rosemary oil, and eucalyptus oil. The results obtained showed that thieves oil was effective against all the organisms tested, yet some of its components were more effective.

Identifying Local Sources of Antibiotic Resistance Genes and Their Effect on Surrounding Microbial Populations. Robin Morrison, Rachel Burckhardt, and Tim Keeton, Alma College

Antibiotic resistance remains an ever-increasing problem in both human and animal medicine. Recently there has been an increased interest and awareness of the impact Confined Animal Feeding Operations (CAF0s) and other animal/human waste producers have on the distribution of Antibiotic Resistance Genes (ARGs). Our increasing use of antibiotics in clinics and animal feedlot operations has greatly accelerated the spread of resistance genes in the environment. To test whether potential local ARG sources are altering the occurrence of ARGs in the environment, DNA is extracted from various soil/streambed sediment samples, then analyzed by standard polymerase chain reactions specific for known tetracycline resistance genes. We have been able to detect TetR genes in sediments from a drainage ditch particularly effected by CAFO waste disposal; this same gene family normally appears to have a limited distribution in the area. We are also beginning to supplement these data with studies of 1) the potential impact of the local municipal wastewater treatment plant effluent on the Pine River, and 2) sediment bacterial populations themselves, determining whether the presence of resistance genes is leading to changes in the microbial flora of local streams and rivers.

Nuclear Localization Sequence of CdtB from Aggregatibacter actinomycetemcomitans. Paul Bermudez, University of Michigan--Flint

Cytolethal distending toxin, Cdt, is a virulence factor of the periodontal disease causing bacterium Aggregatibacter actinomycetemcomitans. Cdt is an AB type toxin, with the specific receptor subunits named CdtA and CdtC, and the cytotoxic component designated CdtB. CdtB exhibits DNase I activity, disrupting the phosphodiester bonds in chromosomal DNA. In an attempt to identify the nuclear localization sequence of CdtB of A. actinomycetemcomitans, site-directed mutagenesis was used to change consecutive arginines to serine and threonine, CdtB (R189S/R190T) and CdtB (R125S/R126T). These sequences were chosen for mutation as they fit the model nuclear localization sequence. Microscopic analysis of isolated nuclei from CHO cells exposed to reconstituted toxin suggested that CdtB (R125S/R126T) maintained nuclear localization, while nuclear localization of CdtB (R189S/R190T) was significantly diminished. For quantitative data, a colony formation assay was performed to measure the effects of the CdtB mutants on CHO cells. The results of the colony formation assay supported the findings in the isolated nuclei, as CdtB (R189S/R190T) showed less toxicity than CdtB (R125S/R126T). A DNase 1 activity assay verified that the mutations did not significantly affect the DNase activity of the CdtB subunit. Thus, arginines 189 and 190 appear to be critical for the nuclear localization of CdtB.

The Role of a UvrD Helicase and the SOS Response in Pseudomonas syringae pv. tomato strain DC3000 Pathogenesis. (Poster) Natalia Porcek, Xinru Zhou, Derek Waterstradt and Julie Zwiesler-Vollick, Lawrence Technological University

Pseudomonas syringae pv. tomato strain DC3000 (Pst DC3000) is a bacterial plant pathogen. It can infect both the economically important crop plant tomato as well as the model plant species Arabidopsis thaliana. Virulence in Pst DC3000 is known to require the type ill secretion system and its effectors, as well as the phytotoxin coronatine. A previous mutagenesis project discovered that uvrD mutants of Pst DC3000 are less virulent than the wildtype strain. The uvrD gene encodes a type 11 DNA helicase involved in DNA replication and repair. However, the uvrD mutant is not compromised in normal growth. The uvrD mutant does appear to have altered levels of mRNA encoding proteins of the coronatine biosynthetic pathway, the type III secretion system and its effectors. Our hypothesis is that the reduced virulence seen in the Pst DC3000 uvrD mutant is due to perturbation of the SOS response. In order to test this hypothesis, we are generating lexA mutants of Pst DC3000. LexA is a key regulator of the SOS response and we will use these new mutants to determine if regulation of the SOS response, the type III secretion system, and coronatine biosynthesis are linked.
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Publication:Michigan Academician
Geographic Code:1USA
Date:Mar 22, 2013
Words:748
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