Vol. 37, No. 5 APPLIED AND ENVIRONMENTAL MICROBIOLOGY, May 1979, p. 878-885 0099-2240/79/05-0878/08$02.00/0 Comparative Effects of Aroclor 1254 (Polychlorinated Biphenyls) and Phenanthrene on Glucose Uptake by Freshwater Microbial Populations G. S. SAYLER,* L. C. LUND, M. P. SHIARIS, T. W. SHERRILL, AND R. E. PERKINS Department of Microbiology and The Graduate Program in Ecology, The University of Tennessee, Knoxville, Tennessee 37916 Received for publication 22 February 1979 The effects of polychlorinated biphenyl (PCB) and phenanthrene stress on glucose uptake by natural microbial populations were examined by the hetero- trophic potential technique. Temporal and spatial distributions in glucose uptake velocities were examined for natural samples as well as PCB- and phenanthrene- stressed samples. Statistical analysis indicated significant variability among the various samples. It was demonstrated that the environmental variables contrib- uted significantly to the variability in uptake kinetics. Although general trends indicated a PCB-induced stimulation in uptake velocities, these trends were in part masked by sample variability. Data analysis indicated no statistically signif- icant PCB or phenanthrene effect on either total glucose uptake velocities or the proportion of "'CO2 evolved, as compared to natural unstressed samples. Numerous investigators have demonstrated the role and abilities of microorganisms in the aquatic decomposition of environmental pollu- tants. However, relatively little information is available concerning the effects of environmen- tal contaminants on aquatic microbial commun- ities. Toxicant perturbations of aquatic ecosystems may adversely effect the overall microbial com- munity or specific microbial populations within the community. Either type of effect may cause serious disruptions in productivity, nutrient and element cycling, and decompositional activity. The consequences of such perturbations may pose a threat to the stability of an aquatic eco- system as serious as the failure of microorga- nisms to degrade a specific toxicant. This study was undertaken to elucidate the effects of Aroclor 1254, a group of (commercial preparation) polychlorinated biphenyls (PCB), and a model polycyclic aromatic hydrocarbon, phenanthrene (PHE), upon glucose uptake by an aquatic microbial community. Both PCBs and polycyclic aromatic hydrocarbons are rec- ognized as persistent aquatic contaminants of global distribution (2, 8, 14-16, 28). In addition, their potential for continued contamination of aquatic systems seems assured due to their past heavy usage, in the case of PCBs, and their relationship to fossil fuel technology, in respect to the polycyclic aromatic hydrocarbons. Both groups of contaminants share similar physical and chemical characteristics, including low wa- ter solubility: ca. 56 ,ug liter-' (13) and 1.6 mg liter-' (34), respectively, for Aroclor 1254 and PHE. In addition, both PCB and PHE have been shown to be subjected to biodegradation (3, 9, 10, 19, 21, 27, 33). Glucose uptake velocities were chosen as a parameter for measuring the effects of PCB and PHE upon heterotrophic microbial activity. The "heterotrophic potential" assay has been sug- gested as a sensitive method for the assessment of eutrophication (1). It has also been applied, in a comparative fashion, for industrial and do- mestic wastewater analysis (18). Although vari- able in its information content, the assay pro- vides an index for gross heterotrophic metabo- lism if respiratory corrections (17) are included. Numerous investigators have employed a vari- ety of techniques to assess the relative hetero- trophic potential of aquatic habitats. It was felt that these techniques would provide a frame- work for elucidating toxicant effects on hetero- trophic metabolism. In addition, valuable infor- mation would be obtained on the consequences of heterotrophic potential assessment in habitats with an unrecognized source of contamination. MATERIALS AND METHODS Sampling. Samples were collected from five sam- ple sites located on Center Hill Reservoir in central Tennessee (Fig. 1). Center Hill Reservoir is a U.S. Army Corps of Engineers impoundment of the Caney Fork River. The reservoir lies within the eastern high- land rim of Tennessee at an elevation of 648 feet (ca. 878 on July 23, 2020 by guest http://aem.asm.org/ Downloaded from