The use of transpositional mutagenesis to study bacterial virulence
Extracellular protease of A. hydrophila was shown to be lethal factor for fish. Protease deficient mutants were obtained from A. hydrophila strain 79. A. hydrophila was mutagenized by inserting Tn10 (tetracycline resistance factor) into the chromosome. This was achieved by conjugation between A. hydrophila and E. coli which contains Tn10 carried on the suicide vector pRK2013. Virulence of the protease deficient mutants was determined by injecting into channel catfish and comparing the mortalities produced by the mutants to that produced by the wild type strain. Protease deficient isolates were non virulent when inoculated into channel catfish (compared to the wild type strain). Proteolytic activities of some protease deficient isolates were compared to the activities of the wild type strain using a quantitative plate technique. The following substrates were used to study the proteolytic activities: casein, gelatin, elastin, staphylococcus and klebsiella. Loss of the proteolytic activity of caseinase, gelatinase and elastase was associated with the loss of virulence of A. hydrophila. Acquiring the DNA from the media was studied using a new transformation technique; no artificial competence was provided. A strain of Escherchi coli, Edwardsiella ictaluri, and Aeromonas hydrophila acquired antibiotic resistance markers when they were grown on media containing the target antibiotic and the resistance markers. When homologous and heterologous {sup 32}P-labelled DNA were supplied to growing cultures of A. hydrophila, A. hydrophila cells and their chromosomes were found labelled. Total cellular radioactivity of the culture receiving heterologous labelled DNA was higher than the culture receiving homologous DNA; however the chromosomal radioactivity was on the opposite where it was higher in case of the culture receiving homologous DNA.
- Research Organization:
- Georgia Univ., Athens, GA (United States)
- OSTI ID:
- 5473942
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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FISHES
BACTERIAL DISEASES
PEPTIDE HYDROLASES
ENZYME ACTIVITY
ANTIBIOTICS
BIOLOGICAL MARKERS
DNA
DNA HYBRIDIZATION
ESCHERICHIA COLI
MUTAGENESIS
MUTANTS
PHOSPHORUS 32
TRACER TECHNIQUES
ANIMALS
ANTI-INFECTIVE AGENTS
AQUATIC ORGANISMS
BACTERIA
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
DAYS LIVING RADIOISOTOPES
DISEASES
DRUGS
ENZYMES
HYBRIDIZATION
HYDROLASES
INFECTIOUS DISEASES
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
MICROORGANISMS
NUCLEI
NUCLEIC ACIDS
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
PHOSPHORUS ISOTOPES
RADIOISOTOPES
VERTEBRATES
550901* - Pathology- Tracer Techniques