Masters Theses

Keywords and Phrases

Antibiotics; Extremophiles; Halomonas eurialkalitoleranis


"Soap Lake, located in Washington State, is a meromictic, soda lake. Many bacterial isolates retrieved from Soap Lake have been noted to possess resistance to multiple antibiotics. A likely explanation for the wide range of antibacterial resistance exhibited by these strains is due to the impact of high alkalinity on the antibiotics themselves and not due to the presence of antibiotic resistance genes. The aim of our study was to determine if select antibiotics are effective against Halomonas eurialkalitoleranis, a bacterium capable of growth over a wide range of neutral to alkaline pH values, to investigate the influence of alkalinity on antibiotic activity. Five strains of Halomonas eurialkalitoleranis were isolated from Soap Lake sediment. Halomonas eurialkalitoleranis Isolate 9 was inoculated into media buffered over a range of pH values, 7-11. Select antibiotics; tetracycline, ampicillin, vancomycin, neomycin trisulfate salt, demeclocycline, sulfamethizole, kanamycin, chloramphenicol, streptomycin, roxithromycin, erythromycin, and sulfamethaxole, were suspended in inoculated media, to determine their minimum inhibitory concentration (MIC) over the range of pH values tested. Tetracycline, ampicillin, kanamycin, neomycin, roxithromycin, and streptomycin, were found to become ineffective against Isolate 9 at pH values above 8. Vancomycin did not produce statistical differences in MIC values at any pH tested. Erythromycin and sulfamethizole were found to be more effective against Isolate 9 at pH 11 than in neutral media. In addition, polymerase chain reactions were performed to determine if Isolate 9 possessed known genes for antibiotic resistance against the twelve antibiotics tested. Isolate 9 was found to possess resistance genes for all antibiotics tested, except kanamycin and streptomycin."--Abstract, page iv.


Mormile, Melanie R.

Committee Member(s)

Westenberg, David J.
Ercal, Nuran


Biological Sciences

Degree Name

M.S. in Applied and Environmental Biology


Missouri University of Science and Technology

Publication Date

Summer 2015

Journal article titles appearing in thesis/dissertation

  • Antibiotic resistance, agriculture, extremophiles, and the resistome: A review
  • Halomonas eurialkalitoleranis sp. Nov., a novel halotolerant, alkaliphilic bacterium isolated from Soap Lake, Washington
  • pH dependent antibiotic resistance of an alkaliphilic halotolerant bacterium isolated from Soap Lake, Washington
  • Antibiotic resistance gene profile of halomonas eurialkalitoleranis, a novel bacterium isolated from Soap Lake, Washington
  • Soap Lake and the Salton Sea: A comparison of microbial diversity with respect to chemical and physical properties of the water and soil sediments


xii, 129 pages

Note about bibliography

Includes bibliographical references.

Geographic Coverage

Soap Lake (Grant County, Wash. : Lake)


© 2015 Tiffany Charlynn Edwards, All rights reserved.

Document Type

Thesis - Open Access

File Type




Subject Headings

Antibiotics -- Research -- United States
Drug resistance in microorganisms
Extreme environments -- Microbiology

Thesis Number

T 10736

Electronic OCLC #



Thesis Location