Defense Date

7-14-2008

Graduation Date

Summer 2008

Availability

Immediate Access

Submission Type

thesis

Degree Name

MS

Department

Biological Sciences

Committee Chair

John Stolz

Committee Member

Partha Basu

Committee Member

Mary Alleman

Committee Member

Michael Jensen-Seaman

Keywords

arsenic, MLHE-1, Alkalilimnicola, arsenite, oxidase

Abstract

Alkalilimnicola ehrlichii strain MLHE -1T is a gram negative haloalkaliphilic gammaproteobacterium isolated from Mono Lake, CA. It has the unique ability to grow both aerobically as a heterotroph (with oxygen and acetate) and anaerobically as a chemolithoautotroph by coupling arsenite oxidation to nitrate reduction. Its genome (3.276 MB, 67.53% mole GC) has been sequenced to closure and annotated (2883 putative ORFs). The pathways involved in nitrogen (e.g., denitrification, assimilation), sulfur, and carbon metabolism (glycolysis, gluconeogenesis), carbon fixation, tricarboxylic acid cycle, and motility (flagella, pili) are described herein. Though no homolog for arsenite oxidase was found, two putative arsenate reductases (arr) were identified along with arsenic resistance genes (ars). One reductase homolog (Mlg0215-Mlg0218) was expressed only under anaerobic conditions and was shown to exhibit both arsenate reductase and arsenite oxidase activity. Proteomics, blue native gels, and enzyme activity assays suggest that it functions primarily as the arsenite oxidase.

Format

PDF

Language

English

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