Stability of cystic fibrosis associated mucoid pseudomonas aeruginosa in culture
Date Issued
August 1, 1981
Author(s)
Boyce, John Rudolph
Advisor(s)
Robert V. Miller
Additional Advisor(s)
Raymond W. Beck
Jeffrey M. Becker
David A. Bemis
Abstract
Reversion of a mucoid strain of Pseudomonas aeruginosa to the non-mucoid phenotype was studied using a Tris-buffered minimal growth medium. Non-mucoid revertants accumulated to higher levels in stationary, as opposed to shaken cultures. Addition of 0.01 mM iron to stationary cultures, as either FeS04 or FeCl3, resulted in the growth of non-mucoid revertants to levels exceeding 90% of the total viable cells in the culture after 3 days of incubation. In contrast, mucoid cells were stable for up to 7 days in shaken cultures without supplemental iron, and non-mucoid revertants rarely reached 1% of the total viable cells in the culture. Calcium and magnesium, in concentrations from 0.3 to 3.0 mM, had no detectable effect on the growth or stability of the mucoid strain. In cultures designed for anaerobic respiration, using nitrate as the terminal electron acceptor, the mucoid cells grew to levels similar to those attained in shaking, aerobic cultures. In such cultures, non-mucoid revertants did not accumulate to high levels, even in the presence of 0.01 mM iron. Data indicate that non-mucoid revertants likely arise by spontaneous mutation, and are selected for in stationary cultures due to a motility advantage over the mucoid cells which was confirmed by electron microscopic examination. Growth of mucoid cells to maximum levels limits the accumulation of non-mucoid revertants in the culture.
Degree
Doctor of Philosophy
Major
Microbiology
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Thesis81b.B689.pdf
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