TitleGrowth, genes, genomes
NameRauschenbach, Ines (author), Häggblom, Max M. (chair), Kerkhof, Lee (internal member), Bini, Elisabetta (internal member), Yee, Nathan (outside member), Rutgers University, Graduate School - New Brunswick,
SubjectMicrobiology and Molecular Genetics,
Selenium ores ,
DescriptionArsenic (As) and selenium (Se) are naturally occurring metalloids in the Earth’s crust. Their speciation is governed by the microbial communities in various environments which influences their mobility among the soil, water, and air interface. Microorganisms can utilize As and Se oxyanion as terminal electron acceptors in dissimilatory reduction. These organisms are ubiquitous and phylogenetically diverse. The objectives of the studies in this thesis were to gain an understanding of the metabolism of As and Se respiring bacteria, analyze the genes encoding enzymes involved in respiration and understand how these enzymes are regulated in the presence of various electron acceptors. We were able to isolate two novel As and Se respiring bacteria from different environments; from a wastewater treatment facility in Verona, NJ and an estuarine canal from Chennai, India. Based on 16S rRNA gene analysis, strain S4 was classified as a novel genus and species, Selenovibrio woodruffi and strain S5 as a novel species, Desulfurispirillum indicum. We analyzed the genome of D. indicum and examined the expression of putative reductases to further understand respiratory metabolism of As and Se oxyanions. Five molybdoenzyme genes were identified in the genome of strain S5, three of which we were annotated to encode for a respiratory arsenate reductase arr, periplasmic nitrate reductase nar, and respiratory nitrate reductase nap. Also, an arsenate resistance system, ars, was identified. We were not able to positively identify a selenate reductase gene. Gene expression studies revealed that arr was an inducible gene and the only gene highly expressed during arsenate respiration. Growth studies showed that selenate respiration was inhibited by nitrate. Lastly, we also enriched activated sludge samples for tellurium oxyanion respiring bacteria. Thus, we not only added novel, phylogenetically different organisms to the ever-increasing list of As and Se respiring microbes, we also provided insights into the genes and enzymes involved in As and Se respiration and how they are regulated.
NoteIncludes bibliographical references
Noteby Ines Rauschenbach
CollectionGraduate School - New Brunswick Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.