Species distribution and temperature relations of coliform populations from uninhabited watershed areas

Abstract

Fifty-seven water samples in all were collected in a northern (latitude 69° N) and in a southern (latitude 61° N) region from waters in the “natural state.” Coliform populations were studied by collecting random isolates of typical sheen colonies from Endo LES 35° C cultivations. The maximum growth temperatures of 607 strains were measured. Identification of 372 isolates was attempted by using the API 20EC and 20E systems. Eleven species were found—seven of them common to both regions. Twenty-nine percent of the strains could not be identified. The most frequent species was Serratia fonticola (26% of all strains tested), the second was Hafnia alvei (14%), and the third Enterobacter cloacae (13%; only encountered in the north). The strains able to grow at or above 44. 5°C were identified as Escherichia coli. In the southern region, environmental coliforms (S. fonticola and H. alvei) so completely outnumbered E. coli that it was met only once among the 438 total coliform isolates, whereas 23% of the isolates from the northern region were E. coli. Typical pipeline/biofilm coliform types were not found, with the exception of numerous E. cloacae strains in the most remote lake samples collected and one Klebsiella oxytoca in a brook. The fecal coliforms (all of them E. coli) were concluded to be of recent animal origin. The standard fecal coliform analysis was estimated to function extremely well in the pristine waters of our subarctic climate. The total coliform analysis has no indicator value under these circumstances.