title: Two genes from the capsule of Aeromonas hydrophila (serogroup O:34) confer serum resistance to Escherichia coli K12 strains.
abstract: The Escherichia coli DH5alpha strain as well as other K12-derived strains are unable to produce O-specific lipopolysaccharide and are thus rough and serum-sensitive. One representative recombinant clone (COS-SR1) containing Aeromonas hydrophila (serogroup O:34) chromosomal DNA conferred serum resistance to E. coli K12 strains. Genetic, biochemical, and immunological studies suggested that the two genes (orf1 and wcaJ) identified in a subclone (pAC-SR9) of COS-SR1 are necessary for the production of the colanic acid capsule at 37 degrees C on E. coli DH5alpha, rendering the strain serum-resistant. A. hydrophila strains from serogroup O:34 are able to produce capsule when they grow both in synthetic medium and in an autolysate of fish viscera. However, defined wcaJ insertion mutants of A. hydrophila 1051-88 (serogroup O:34) are unable to produce capsule on these media. This strongly suggests that both genes belong to the gene cluster responsible for capsule production (wca) of A. hydrophila 1051-88 (serogroup O:34).
authors.affiliation: Departamento de Microbiología, Facultad de Biología, Universidad de Barcelona, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Aguilar
authors.forename: S
authors.initials: S
authors.lastname: Merino
authors.forename: M M
authors.initials: MM
authors.lastname: Nogueras
authors.forename: M
authors.initials: M
authors.lastname: Regué
authors.forename: J M
authors.initials: JM
authors.lastname: Tomás
mesh_terms: D016980:Aeromonas hydrophila / Q000235:genetics* / Q000276:immunology*; D000595:Amino Acid Sequence; D000818:Animals; D016667:Bacterial Capsules / Q000235:genetics / Q000276:immunology; D001483:Base Sequence; D003167:Complement Activation / Q000235:genetics / Q000276:immunology; D004926:Escherichia coli / Q000235:genetics* / Q000276:immunology*; D005818:Genetic Engineering; D006801:Humans; D008969:Molecular Sequence Data; D019081:O Antigens / Q000276:immunology*; D011134:Polysaccharides / Q000235:genetics / Q000276:immunology; D011817:Rabbits; D017421:Sequence Analysis
chemical_list: D019081:O Antigens; D011134:Polysaccharides; C004275:colanic acid