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Regulation of exopolysaccharide synthesis

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dc.contributor.advisor Trempy, Janine E.
dc.creator Dierksen, Karen P.
dc.date.accessioned 2012-10-10T19:48:27Z
dc.date.available 2012-10-10T19:48:27Z
dc.date.copyright 1996-06-12
dc.date.issued 1996-06-12
dc.identifier.uri http://hdl.handle.net/1957/34322
dc.description Graduation date: 1997 en_US
dc.description.abstract Lactococcus lactis subsp. cremoris Ropy 352 and L. lactis subsp. cremoris Hollandicus produce an exopolysaccharide (EPS) that imparts commercially desirable textural and rheological properties to fermented milk products. This ropy phenotype is expressed under specific environmental conditions. A mucoid EPS phenotype, also expressed under specific environmental conditions, but not involved in the fermentation of ropy milk was identified. The two EPS phenotypes can be expressed individually or concurrently. Genetic regulators involved in expression of the EPS phenotypes were sought. DNA probes and polyclonal antiserum specific to two regulators of EPS in Escherichia coli, Lon protease and RcsA protein, were used to probe ropy and non-ropy strains of L. lactis. The two ropy strains of L. lactis subsp. cremoris, Ropy 352 and Hollandicus, expressed significantly less of the Lon protein than non-ropy strains. Southern and Western blot analysis was extended to a number of Gram negative and Gram positive bacteria. All of the Gram negative bacteria probed contained DNA sequences that hybridized to the Ion and rcsA gene probes, and all of these bacteria has at least one protein that reacted with antiserum to E. coli Lon and RcsA proteins. Two of the Gram positive bacteria contained DNA sequences that hybridized to the E. coli rcsA probe. None of the other Gram positive organisms contained DNA sequences that hybridized to the rcsA or the Ion probes. However, all the Gram positive bacteria contained one high molecular weight protein that reacted with Lon antiserum. In addition, Streptococcus salivarius expressed a protein that reacted with RcsA antiserum. In the course of this study, a second RcsA protein was identified in E. coll. The two RcsA proteins are expressed from one rcsA gene. One RcsA protein is not the proteolytic product of the other RcsA protein. Limited peptide digest profiles of each RcsA protein reveals almost identical peptides indicating the two proteins share a high degree of homology but are not identical. Ferguson plot analysis strongly suggests that the two RcsA proteins differ by size not by charge. Neither RcsA protein can be detected in cells mutant for Ion and rcsB. en_US
dc.language.iso en_US en_US
dc.subject.lcsh Lactococcus lactis -- Genetics en_US
dc.subject.lcsh Microbial exopolysaccharides -- Synthesis -- Regulation en_US
dc.title Regulation of exopolysaccharide synthesis en_US
dc.type Thesis/Dissertation en_US
dc.degree.name Doctor of Philosophy (Ph. D.) in Microbiology en_US
dc.degree.level Doctoral en_US
dc.degree.discipline Science en_US
dc.degree.grantor Oregon State University en_US
dc.contributor.committeemember Daeschel, Mark
dc.contributor.committeemember Moore, Larry
dc.contributor.committeemember Leong, Joanne
dc.contributor.committeemember Sandine, William
dc.description.digitization File scanned at 300 ppi (Monochrome, 256 Grayscale) using Capture Perfect 3.0.82 on a Canon DR-9080C in PDF format. CVista PdfCompressor 4.0 was used for pdf compression and textual OCR. en_US
dc.description.peerreview no en_us

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