title: Minimum growth temperatures of Listeria monocytogenes and non-haemolytic Listeria.
abstract: Minimum growth temperatures and those of decreased growth were determined for 100 strains of listerias. The ability of 78 strains of Listeria monocytogenes isolated from animals and 22 non-haemolytic strains to grow at low temperatures was studied, using a flooding technique, in a plate-type continuous temperature gradient incubator at temperatures between -1.6 and 14.5 degrees C. The mean minimum temperature for L. monocytogenes was +1.7 +/- 0.5 degrees C. The growth of non-haemolytic listerias was unobservable at +1.7 +/- 0.5 degrees C. The L. monocytogenes strains grew at about 0.6 degrees C lower than the non-pathogenic strains. No differences in growth temperatures were observed among L. monocytogenes strains isolated from different sources. The serovars with the OI antigen grew at lower temperatures (+1.0 +/- 0.3 degrees C) than the other common serovar 4b (+1.3 +/- 0.4 degrees C). The results indicate that L. monocytogenes grows better than non-haemolytic strains under cold conditions. The possible role of haemolysins as growth factors is also discussed.
authors.affiliation: Department of Bacteriology and Serology, National Veterinary Institute, Helsinki, Finland.
authors.forename: J R
authors.initials: JR
authors.lastname: Junttila
authors.forename: S I
authors.initials: SI
authors.lastname: Niemelä
authors.forename: J
authors.initials: J
authors.lastname: Hirn
mesh_terms: D000818:Animals; D008087:Listeria / Q000145:classification / Q000254:growth & development* / Q000302:isolation & purification; D008089:Listeria monocytogenes / Q000145:classification / Q000254:growth & development* / Q000302:isolation & purification; D012703:Serotyping; D013696:Temperature