Host and geographical factors influence the thermal niche of enteric bacteria isolated from native Australian mammals

The thermal profiles of 118 bacterial strains, representing six species of the family Enterobacteriaceae, isolated from a variety of native Australian mammals were determined under in vitro conditions. Each of the bacterial s pecies had a unique thermal profile and differed in their minimum or maximu m temperature for growth and in their response to changing temperatures. Th e taxonomic classification of the host from which the bacterial strains wer e isolated explained a significant amount of the variation in thermal profi le among strains of a species. Host effects were detected at all taxonomic levels: order, family, genus, and species. The locality (State or Territory ) or climate zone from which the strain was collected explained a significa nt amount of the variation in the thermal profile of Citrobacter freundii, Enterobacter cloacae and Klebsiella pneumoniae strains. Genetically similar strains, as determined by allozyme profiles, had similar thermal profiles for the bacterial species Hafnia alvei and Escherichia coli. The results of this study indicate that there are potentially many aspects of host biolog y that may determine the thermal profile of these bacteria.