Survival of Antarctic Bacteria Exposed to Ultraviolet and Visible Light

Date of Graduation

Fall 1989

Degree

Master of Science in Biology

Department

Biology

Committee Chair

Roar Irgens

Abstract

The four strains of bacteria used in this study were isolated from six or eighteen meters depth at McMurdo Sound, Antarctica. The two strains isolated from six meters depth, 70T and 71T, were pigmented and extracts of these pigmented organisms showed absorption spectra characteristic of carotenoid pigments (450-550 nm). The two isolates from a depth of 18 meters, 64T and 21B were colorless. All strains except 64T were catalase positive. All cultures were sampled in log phase, diluted in phosphate buffer with 2.0% NaC1 and exposed to sunlight (20,000 Lux), UV-C (1.0 X 10⁻⁶ W/cm²), UV-B (1.0 X 10⁻⁶ W/cm²) and UV-A (1.5 X 10⁻⁶ W/cm²). The cultures were diluted to a final absorbance of 0.01 at 540 nm for sunlight and to 0.1 for the UV light exposures. All strains were sensitive to UV-C exposure with 64T dying within one hour. The survival of pigmented and colorless strains showed no relationship. Strains 70T and 21B survived well, while both 71T and 64T perished rapidly. Survival of pigmented and colorless cells also showed no relationship when exposed to UV-B and UV-A. The pigmented strain 70T was sensitive whereas no effect was shown for the colorless strains. Strain 71T was very susceptible to both UV-B and UV-A.

Subject Categories

Biology

Copyright

© Timothy A Klages

Citation-only

Dissertation/Thesis

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