Date of Graduation

Spring 2017

Document Type

Honors Research Project

Degree Name

Bachelor of Science

Major

Biology

Research Sponsor

Dr. Hazel Barton

First Reader

Dr. John Senko

Second Reader

Dr. Don Ott

Abstract

The iron caves in Brazil are thought to form through a cycle of Fe(III)-reduction and Fe(II)-oxidation; the Fe(II) is washed out of the cave walls by rainwater, where it is oxidized to Fe(III) and deposited in iron-oxide crusts. Bacteria are known to reduce Fe(III) in the caves, but what species may be oxidizing Fe(II) is still unknown. Our hypotheses was another bacterial species was involved and our initial assays were aimed at isolating Fe(II)-oxidizing bacteria; however all our Fe(II)-oxidizing cultures were contaminated with fungi when Fe(II)-oxidation was seen. Antifungals were used to inhibit growth of fungal species, which inhibited both fungal growth and Fe(II)-oxidation. Serially diluting cave samples also did not lead to isolation of bacterial species. Antibacterial agents added to the media had no effect and there was no inhibition of fungal growth on Fe(II)-oxidation. Together these data suggested that fungi were the dominant Fe(II)-oxidizing species in our sample. Six fungal isolates were screened by PCR amplification and restriction fragment length polymorphism analysis of the ITS sequence. These data suggested a single species was present based on the ITS sequence. Sequencing of the ITS gene and phylogenetics showed it was closely related to Sagenomella stratispora. This particular species of fungus has never been previously described in a cave setting, however given that this species lives in soils and the proximity of the cave to the surface and jungle, this discovery was no surprise.

Included in

Microbiology Commons

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