Thesis
A multi-locus sequence analysis of environmental strains of Enterobacter cloacae and their placement within the E. cloacae complex
Washington State University
Master of Science (MS), Washington State University
2013
Handle:
https://hdl.handle.net/2376/107299
Abstract
Enterobacter cloacae is a bacterial storage pathogen of onion causing Enterobacter bulb decay and has been described as a plant pathogen on numerous other plant species as well as an opportunistic human pathogen causing nosocomial infections in immunocompromised individuals. The identification of isolates as E. cloacae requires a large number of physiological tests and the results are inconsistent (Kämpfer et al 2007). This is further complicated by the fact that E. cloacae is part of what is referred to as the Enterobacter cloacae complex (ECC), which is composed of six closely related Enterobacter species with very similar biochemical profiles (Hoffmann and Roggenkamp 2003). To determine the association of plant-associated environmental and medical isolates within the ECC, a MLSA using four housekeeping genes, fusA, gyrB, leuS, and rpoB was performed. Thirty environmental strains of E. cloacae obtained from onion and other vi environmental sources along with sequences from ECC medical strains analyzed in the Paauw et al. (2008) study, were included in this analyses. Each gene was phylogenetically estimated using MrBayes and PAUP*. Individual gene trees were evaluated for congruency and recombination and all four genes were combined for each isolate. The MLSA analysis revealed that seven clades that correlate with the Paauw et al (2008) study were present within the ECC. Only five clades, 2, 3, 4, 5 and 7, contained environmental strains. A majority of plant-associated strains, originally designated as E. cloacae, were found within clade 4 with strains defined as E. ludwigii. Almost all E. cloacae strains obtained from onions were placed in clade 4, along with an E. cloacae strain obtained from switchgrass. E. cloacae strain obtained from ginger was placed in clade 7, strains obtained from papaya, noni juice and an oriental fruit fly in where placed in clade 2, while the biocontrol strains found on cucumber were placed in clade 5. The use of MSLA allows for a more consistent, reliable and easier placement of environmental strains of E. cloacae within the ECC compared to alternatives such as biochemical tests. Biochemical test used to separate out this these environmental strains was inconclusive
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Details
- Title
- A multi-locus sequence analysis of environmental strains of Enterobacter cloacae and their placement within the E. cloacae complex
- Creators
- Austin Alan Bates
- Contributors
- Brenda K. Schroeder (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Plant Pathology, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900525378701842
- Language
- English
- Resource Type
- Thesis