Date of Award:

5-1-1992

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Biology

Department name when degree awarded

Biology (Molecular Biology)

Committee Chair(s)

Anne Anderson

Committee

Anne Anderson

Committee

Noelle Cockett

Committee

Jack Lancaster

Committee

Gregory Podgorski

Committee

Sherman Thomson

Committee

Dennis Welker

Abstract

Agglutinability in the beneficial fluorescent pseudomonad, Pseudomonas putida isolate Corvallis, with a plant root surface agglutinin is correlated with establishment of a bacterial population at the root-microbe interface. Agglutinability in P. putida Corvallis is conditioned in vitro by nutrient status and growth phase. Genetic analyses of the agglutination phenotype in P. putida indicate a locus, aggA, on a 2.7 kbp EcoRI-Hind III fragment is involved in manifestation of the agglutination phenotype and in adherence by the cells to bean root surfaces. Sequence analyses predict the presence of two potential open reading frames, ORFAGG1 and ORFAGG2, within the 2.7 kbp aggA locus. Sequence and deletion analyses in conjunction with chimeric promoter fusions indicate ORFAGG1, not ORFAGG2, is responsible for agglutination. ORFAGG1, 1,356 nucleotides, encodes a 50 kDa protein that is processed into a 48 kDa periplasmic protein in Escherichia coli expression studies. The promoter region of ORFAGG1 contains promoter sequences resembling the -35/-10 and -24/-12 canonical consensus sequences. The ORFAGG1 promoter is constitutively expressed in vitro in P. putida cells. The aggA locus is expressed in planta, providing a further link between in vitro agglutinability and colonization of the rhizosphere by the bacteria.

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