Shewanella oneidensis MR-1 cell-to-cell signaling and its influences on biogeochemical processes

dc.contributor.authorLearman, Deric Ronalden
dc.contributor.committeechairHochella, Michael F. Jr.en
dc.contributor.committeememberStevens, Ann M.en
dc.contributor.committeememberSchreiber, Madeline E.en
dc.contributor.committeememberLower, Brian H.en
dc.contributor.departmentGeosciencesen
dc.date.accessioned2014-03-14T20:12:43Zen
dc.date.adate2008-06-26en
dc.date.available2014-03-14T20:12:43Zen
dc.date.issued2008-05-29en
dc.date.rdate2008-06-26en
dc.date.sdate2008-06-04en
dc.description.abstractThe goal of this project is to decipher the quorum sensing (cell-to-cell signaling) abilities of Shewanella oneidensis MR-1, a Gram-negative bacterium well known for its ability to use geologic substrates, such as Fe and Mn oxides, for respiratory purposes. Overall our results show that S. oneidensis cannot utilize either an acyl-homoserine lactone (AHL) or AI-2 quorum sensing signal, despite previous work that indicated that it produced an AHL that would enhance it ability to growth in certain anaerobic environments. Using a variety of quorum sensing signal sensors, no evidence could be found that S. oneidensis has a typical AHL signal. An in silco analysis of the genome also produced little evidence that S. oneidensis has the genes to accept or relay an AHL signal. S. oneidensis can produce a luminescence response in the AI-2 reporter strain, Vibrio harveyi MM32. This luminescence response is abolished upon deletion of luxS, the gene responsible for catalyzing AI-2. Deletion of luxS also affected biofilm formation. Within 16 hours of growth in a biofilm flow-through reactor, the luxS mutant had an inhibited ability to initiate biofilm formation. After 48 hours of growth, the mutant's biofilm had developed similarly to wild-type. The addition of synthetic AI-2 did not restore the mutant's ability to initiation biofilm formation, which led to the conclusion that AI-2 is not likely used as a quorum sensing signal in S. oneidensis for this phenotype. Because of the involvement of LuxS in the activated methyl cycle (AMC) in other organisms, growth on various sulfur sources was examined. A mutation in luxS produced a reduced ability to growth with methionine as the sole sulfur source. Methionine is a key metabolite used in the AMC to produce a methyl source in the cell and homocysteine. This data suggests that LuxS is important in metabolizing methionine and the AMC in S. oneidensis.en
dc.description.degreePh. D.en
dc.identifier.otheretd-06042008-121824en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-06042008-121824/en
dc.identifier.urihttp://hdl.handle.net/10919/27946en
dc.publisherVirginia Techen
dc.relation.haspartLearman.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectquorum sensingen
dc.subjectbiofilmen
dc.subjectactivated methyl cycleen
dc.subjectShewanella oneidensis MR-1en
dc.titleShewanella oneidensis MR-1 cell-to-cell signaling and its influences on biogeochemical processesen
dc.typeDissertationen
thesis.degree.disciplineGeosciencesen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.leveldoctoralen
thesis.degree.namePh. D.en

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