Biology ETDs

Publication Date

6-2-1954

Abstract

The problem herein described was initiated while following the growth rate of a culture over a ten-hour period. A flask of polypeptone agar had been held in a 47-degree Celsius water bath to maintain it melted so that the plates could be poured periodically. The plates poured during the last two or three hours were found to be heavily contaminated with a Gram-positive, aerobic, sporeforming bacillus. Aseptic technique had been used in pouring the plates; however, external contamination was possible over the long pouring interval, so the test was repeated incubating a flask of the sterilized medium in the water bath for seven to eight hours before pouring plates. Again growth was demonstrated, so the source of the microorganism could only have been one of the ingrediants used to make the medium. The constituents of the medium were beef extract, polypeptone, and agar. A stained smear of the beef extract revealed many spores indicating this as a possible source of the microorganism. An unusual degree of heat resistance in these spores was evident because the medium had been autoclaved at 121° C. for 15 minutes.

Language

English

Document Type

Thesis

Degree Name

Biology

Level of Degree

Masters

Department Name

UNM Biology Department

First Committee Member (Chair)

Richard B. Johnson

Second Committee Member

Howard J. Dittmer

Third Committee Member

Clarence Clayton Hoff

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