First Advisor

Anna-Louise Reysenbach

Term of Graduation

Winter 2002

Date of Publication

3-19-2002

Document Type

Thesis

Degree Name

Master of Science (M.S.) in Biology

Department

Biology

Language

English

Subjects

Marine microbiology, Hydrothermal vent ecology, Bioremediation, Extreme environments -- Microbiology

Physical Description

1 online resource (vi, 69 pages)

Abstract

Microbes inhabiting the deep subsurface play an important role in geochemical processes and may be of practical value in bioremediation and biotechnology. Hydrothermal vents and the deep gold mines of South Africa have be likened to "windows" into the subsurface biosphere. The aim of this research was to isolate and characterize microbes involved in iron-cycling from deep-sea hydrothermal vents and from the deep gold mines of the Witwatersrand Basin. Three mesophilic bacteria, strains BB4, W3, and A6 were isolated from sulfide chimneys at 13°N and a thermophilic bacterium, strain GB21 was isolated from Guaymas Basin on the East Pacific Rise. Additionally, a novel bacterium, strain SA 1 was isolated from 837 m below the surface from a gold mine in the Witwatersrand Basin, South Africa.

The mesophilic strains BB4 and W3 belong to the genus Vibrio and strain A6 is a species of Shewanella. All species were able to reduce ferric iron when complex carbon substrates were present in the medium. When grown with acetate as the sole carbon source, ferric iron was only slightly reduced.

A new thermophilic, anaerobic rod-shaped bacterium isolated under iron-reducing conditions, strain GB2 I, was obtained from a deep-sea hydrothermal vent sulfide structure in Guaymas Basin. The cells measured about 3-6 μm in length and about 0.5 μm in width and were encased in a bulbous sheath-like structure, typical of the Thermotogales. The temperature range for growth was 50 to 80°C (fastest growth was about 72 °C). Fastest growth occurred at a pH of 6.0 and a NaCl concentration of 3% (w/v). Strain GB21 was a strict heterotroph, requiring complex proteinaceous substrates for growth. Grown with H2 and S° , strain GB21 reduced the S° to H2S. Strain GB21 reduced ferric citrate in the presence and absence of H2 . Based on the phenotypic and phylogenetic characteristics, it is proposed that the isolate is a novel species within the genus Thermosipho.

Strain SA1 was the first mesophilic, iron-reducing bacterium isolated from the Witwatersrand Basin. Strain SA1 was an obligate anaerobe and heterotroph and seemed to represent a novel species of the genus Fusibacter.

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Persistent Identifier

https://archives.pdx.edu/ds/psu/44685

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