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R O EGEBERG

Publications and source records attributed to R O EGEBERG.

13 recordsLinked to original sources
PubMed1964

SIGNIFICANCE OF SOIL SALINITY ON THE ECOLOGY OF COCCIDIOIDES IMMITIS.

Elconin, Ann F. (University of Southern California, Los Angeles), Roger O. Egeberg, and Margaret C. Egeberg. Significance of soil salinity on the ecology of Coccidioides immitis. J. Bacteriol. 87:500-503. 1964.-An 8-year study of the soil in a small parcel of land where coccidioidomycosis is endemic was conducted. Over 5,000 samples collected from the surface of the soil at monthly intervals were tested for the presence of Coccidioides immitis. These samples were also analyzed to determine their major chemical composition. During the first 3 years, C. immitis was recovered in profusion from the spring samples, but during the next 4 years the fungus virtually disappeared from this endemic area. C. immitis reappeared in the spring of the final year of this study. There had been no significant deviation in the climatic conditions, flora, or fauna of the region. Chemical analysis of soils showed a marked elevation of the soluble salts (principally Na, Ca, SO(4), and Cl) during those years when C. immitis was recovered. The soluble salts, expressed in terms of the saturation extract conductivity, ranged from 11 to 27 in those spring seasons when C. immitis was recovered, and from 3.5 to 8.8 when it was not found. This degree of correlation indicates that the high level of surface salinity encouraged the growth of C. immitis, and could be a factor in accounting for the spotty distribution of this fungus within endemic areas.

Calcium↗
PubMed1964

EFFECT OF SALINITY AND TEMPERATURE ON COCCIDIOIDES IMMITIS AND THREE ANTAGONISTIC SOIL SAPROPHYTES.

Egeberg, Roger O. (University of Southern California, Los Angeles), Ann F. Elconin, and Margaret C. Egeberg. Effect of salinity and temperature on Coccidioides immitis and three antagonistic soil saprophytes. J. Bacteriol. 88:473-476. 1964.-Experiments exploring the factors which determine the ability of Coccidioides immitis to survive and reproduce in the soil in situ are described and discussed. Previous work indicated that soil temperatures and salinity influence the growth and distribution of C. immitis. It was thought that these factors might work through enhancing the growth of C. immitis or inhibiting the growth of its possible antagonists, or both. In searching for antagonists, samples of surface soil from an endemic area were screened by standard culture techniques. Three significant antagonists were isolated and were identified as two strains of Bacillus subtilis, and Penicillium janthinellum. Subcultures of each of these isolates were grown on Saboraud's media modified by sodium chloride and calcium chloride in parallel series. The salts used were the predominant salts, and the range of temperature was comparable to that found in the soil. The organisms were grown at 18 to 27 C and at 40 C. The latter temperature approximated the temperature of the top centimeter of soil for 4 to 6 hr a day in the spring when C. immitis is recovered. P. janthinellum was unable to survive 40 C. The growth of the other two, while unaffected by temperature change alone, was inhibited by the salts. Conversely, C. immitis was stimulated by the salts when grown at the higher temperature. These findings support the hypothesis that markedly increased salinity and seasonal high temperature of the surface soil inhibit or kill these antogonists while enhancing the growth of C. immitis.

Bacillus subtilis↗
PubMed1961

Antifungal agent.

From the soil of the San Joaquin Valley a fungus has been isolated, an extract of which inhibits the growth of Coccidioides immitis on Sabouraud's medium. An acute toxicity study in mice indicates a certain tolerance of the extract. Tentative identification indicates that the fungus is a penicillium.

Animals↗