Minimum growth temperatures of Hafnia alvei and other Enterobacteriaceae isolated from refrigerated meat determined with a temperature gradient incubator

Minimum growth temperatures of Hafnia alvei (n = 156) and other Enterobacteriaceae isolates (n = 162) from refrigerated meat samples (n = 88) and control strains of H. alvei (n = 81) from clinical and environmental samples were determined with a plate-type continuous temperature gradient incubator on nutrient agar. The dominant species, Hafnia alvei and Serratia liquefaciens had mean minimum growth temperatures of 2.6 (range, 0.2–3.7 °C) and 1.7 (range, 0.2–2.6 °C), respectively. Values for other species included: Enterobacter agglomerons, 1.3 (0.7–1.7 °C); Escherichia coli, 8.7 (8.4–8.9); Escherichia vulneris, 1.6 (0.8–2.6 °C); and Serratia fonticola, 2.0 (1.1–3.0 °C). The H. alvei reference strains did not differ markedly from the meat isolates, with the exception of the diarrhoeagenic eaeA positive strains (10.6, 10.2–11.5 °C). The representatives of H. alvei hybridization groups (HG) 1 and 2 did not differ in their minimum growth temperatures. The observed heterogeneity of the minimum growth temperatures of many Enterobacteriaceae species may be explained by limitations of the systems used for identification of enterobacteria, inadequacy of the Enterobacteriaceae taxonomy or true growth temperature heterogeneity within the various species.