Work

Tn916-induced mutations in the hemolysin determinant affecting virulence of Listeria monocytogenes

Year: 1987

Type: article

Abstract: A genetic determinant essential for hemolysin production by Listeria monocytogenes has been inactivated by insertion of transposon Tn916 into L. monocytogenes DNA. The transposon was transferred by means of conjugation of a streptomycin-resistant L. monocytogenes recipient strain with Streptococcus faecalis CG110 on membrane filters. Among the tetracycline-resistant transconjugants, mutants were detected which had lost hemolytic activity. When tested in a mouse model, these mutants appeared to have lost the virulence that characterizes the parental strain. An extracellular protein of 58,000 apparent molecular weight was eliminated in the nonhemolytic mutants. In some of the mutants, the decrease in the production of the 58,000-dalton protein was accompanied by the production of a new protein of 49,000 apparent molecular weight. Hemolytic revertants regained the hemolytic phenotype and virulence and produced the extracellular protein that characterizes the recipient strain. Hybridization studies with Tn916 DNA indicated that the transposon is present in EcoRI and HindIII fragments of the nonhemolytic mutants. Single copies of Tn916 were detected in the chromosomal DNA of two of the three nonhemolytic mutants that were studied in detail. In hemolytic, tetracycline-sensitive revertants Tn916 appeared to be completely excised from the chromosome.

Source: Journal of Bacteriology

DOI: 10.1128/jb.169.3.1291-1297.1987

Authors: S Kathariou, P Metz, H Hof, W Goebel

Institution: University of Würzburg

Language: English

Topic: Listeria monocytogenes in Food Safety

Subfield: Food Science

Field: Agricultural and Biological Sciences

Domain: Life Sciences

SDG: Good health and well-being

Open Access status: green

Funder: Deutsche Forschungsgemeinschaft