Importance of passive diffusion in the uptake of polychlorinated biphenyls by phagotrophic protozoa
Journal Article
·
· Applied and Environmental Microbiology
Unicellular protozoan grazers represent a size class of organisms where a transition in the mechanism of chlorobiphenyl (CB) introduction, from diffusion through surface membranes to ingestion of contaminated prey, could occur. This study compares the relative importance of these two processes in the overall uptake of polychlorinated biphenyls by protists. Uptake rates and steady-state concentrations were compared in laboratory cultures of grazing and nongrazing protozoa. These experiments were conducted with a 10-{micro}m marine scuticociliate (Uronema sp.), bacterial prey (Halomonas halodurans), and a suite of 21 CB congeners spanning a range of aqueous solubilities. The dominant pathway of CB uptake by both grazing and nongrazing protozoa was diffusion. Organic-carbon-normalized CB concentrations (in the protozoan cell) were equivalent in grazing and nongrazing protozoa for all congeners studied. Rate constants for uptake into and loss from the protozoan cell were independently determined by using [3,3{prime}, 4,4{prime}-{sup 14}C]tetrachlorobiphenyl (IUPAC no. 77), 0.38 {+-} 0.03 min{sup {minus}1} and (1.1 {+-} 0.1) x 10{sup {minus}5} (g of organic carbon){minus}{sup {minus}1} min{sup {minus}1}, respectively. Magnitudes of the uptake and loss processes were calculated and compared by using a numerical model. The model result was consistent with data from the bioaccumulation experiment and supported the hypothesis that diffusive uptake is faster than ingestive uptake in phagotrophic unicellular protozoa.
- Research Organization:
- Massachusetts Inst. of Tech., Woods Hole Oceanographic Institution Joint Program in Oceanography, Woods Hole, MA (US)
- OSTI ID:
- 20075760
- Journal Information:
- Applied and Environmental Microbiology, Journal Name: Applied and Environmental Microbiology Journal Issue: 5 Vol. 66; ISSN AEMIDF; ISSN 0099-2240
- Country of Publication:
- United States
- Language:
- English
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