Klebsiella pneumoniae strains isolated from different clinical and environmental sources were examined for resistance to antibiotics, pentachlorophenol, and heavy metals using intracellular ATP measurements. Resistance to kanamycin, neomycin, gentamicin, and tobramycin was noted for the hospital strain but not for the environmentally derived isolates. On the other hand, strains isolated from pulp and paper mill effluents and receiving waters exhibited a higher degree of pentachlorophenol and heavy metal resistance. Chromosomal restriction endonuclease analysis (REA) digests of three environmental strains produced patterns that were different and readily distinguishable. Plasmids were detectable in these same environmental isolates; two of the three carried a 70 × 106 Da plasmid that is thought to mediate both antibiotic and heavy metal resistance.

A firefly luciferase bioluminescent assay ofbacterial adenosine triphosphate ( ATP) was used to measure the toxic effects of metal ions on six bacterial genera isolated from two geographically different marsh treatment systems. The toxicity of eleven different metals, as well as metal mixtures, was monitored using the agar plate test and the resazurin reduction test in addition to measurement of intracellular ATP. All the organisms surveyed tended to be sensitive to much lower concentrations of metals when the metals were present in mixtures. Isolates from a marsh system constructed on normal soil exhibited lower metal resistance patterns than organisms isolated from a marsh built on mine tailings. The intracellular ATP assay appeared to be the most sensitive method of determining the viability of bacterial cells following metal treatment.

Higher land and energy costs have prompted interest in marshes for wastewater treatment. To date, four marsh treatment systems have been built in Ontario at Listowel, Cobalt, Bradford and Port Perry. Of these, the Cobalt marsh is unique in that it is situated in the area of a mine tailings basin. Because metals from mine tailings have been shown to reach the overlyinq waters, it was essential that the effect of leached metals on the micro-bial activities in the system be examined. Factors that were studied were chemical pollutant and pathogen removal, activities of sulfur and nitrogen bacteria, as well as inhibitory effects of toxic metals on the microbiota. Comparisons were made of data collected from the Cobalt and Listowel marshes. Although the metals present in the Cobalt area were shown to be potentially toxic to the marsh microflora, the concentrations of metals in the marsh were not hiqh enough to interfere with microbial activities.

An organized approach, requiring a minimum number of tests, is presented for the relatively rapid identification of a wide range of aerobic heterotrophic bacteria found in freshwater. Bacterial isolates were identified to the genus level and many strains could be identified to the species level with the appropriate use of commercially available bacterial identification panels. Bacteria were separated into four groups based on gram reaction, motility, cell shape and arrangement, spore and pigment production, catalase, oxidase, and O/F glucose tests. Further identification was based on selected tests for each group. Over 95% of the 800 aerobic heterotrophic bacteria isolated from Ontario marshes were identified using the procedures outlined.