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Appl Environ Microbiol. 1975 June; 29(6): 819-825
Copyright © 1975 American Society for Microbiology. All Rights Reserved.

Potential Pathogens in the Environment: Cultural Reactions and Nucleic Acid Studies on Klebsiella pneumoniae from Clinical and Environmental Sources¹

^* Department of Microbiology, Oregon State University, Corvallis, Oregan 97331, and Pacific Northwest Environmental Research Laboratory, U.S. Environmental Protection Agency, Corvallis, Oregon 97330

ABSTRACT

The phenotypic and nucleic acid properties of Klebsiella pneumoniae have been studied on cultures obtained from six different habitats (humans, vegetables, seeds, trees, rivers, and pulp mills). The 19 cultural reactions of 107 isolates varied significantly only in tryptophanase activity and dulcitol fermentation. The percentage of guanine plus cytosine base composition of 41 isolates varied from 53.9 to 59.2%. The range of percentage of guanine plus cytosine base composition for environmental klebsiellas was broader than that for the cultures of human origin. The range of deoxyribonucleic acid relative reassociation (homology) to the human K. pneumoniae reference strain extended from 5% to 100% and the chromosome molecular weights ranged from 2,200 x 10⁶ to 3,000 x 10⁶. The species of K. pneumoniae is thus molecularly more heterogeneous than previously thought and most isolates of human, pulp mill, and river origin are genetically indistinguishable. The presence of K. pneumoniae therefore represents a deterioration of the microbiological quality of the environment and should be considered of public health significance. At the present time the health significance of the molecularly more divergent strains, primarily of vegetable and seed origin, their relationship to klebsiellas of human origin, or to other genera of the Enterobacteriaceae is unclear.

¹ Technical paper no. 3980, Oregon Agricultural Experiment Station.