Characterization of a highly arsenic-resistant microbe

Author (Your Name)

Eleanor E. Windholz, Colby CollegeFollow

Date of Award

2025

Document Type

Honors Thesis (Open Access)

Department

Colby College. Biology Dept.

Advisor(s)

Ron Peck

Second Advisor

Susan Childers

Third Advisor

Suegene Noh

Abstract

Heavy metal pollution in our terrestrial and aquatic ecosystems is a major global concern, as chronic exposure to heavy metals such as arsenic and chromium has dire effects on mammalian health. In these polluted, arsenic-rich environments, microorganisms resistant to heavy metals have been isolated. The microbe isolated in this paper was resistant to As(V) up to 1100 mM, which is significantly higher than most published strains, and resistant to Cr(VI) at concentrations up to 5 mM. The microbe was tentatively identified as Micrococcus luteus, but its high arsenic resistance suggests it may be a novel strain. The ability of the microbe to transform arsenic between oxidation states was supported by two experiments: a conditioned media experiment that indicated the microbe can reduce As(V) to As(III), and a silver arsenate experiment that suggested it can oxidize As(III) to As(V). These findings show that the microbe is a compelling candidate for bioremediation strategies, especially in arsenic-contaminated environments.

Keywords

Arsenic resistance, bioremediation, heavy metals, As(V) reduction, As(III) oxidation, Cr(VI) tolerance

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