title: Protozoan predation in soil slurries compromises determination of contaminant mineralization potential.
abstract: Soil suspensions (slurries) are commonly used to estimate the potential of soil microbial communities to mineralize organic contaminants. The preparation of soil slurries disrupts soil structure, however, potentially affecting both the bacterial populations and their protozoan predators. We studied the importance of this "slurry effect" on mineralization of the herbicide 2-methyl-4-chlorophenoxyacetic acid (MCPA, (14)C-labelled), focussing on the effects of protozoan predation. Mineralization of MCPA was studied in "intact" soil and soil slurries differing in soil:water ratio, both in the presence and absence of the protozoan activity inhibitor cycloheximide. Protozoan predation inhibited mineralization in dense slurry of subsoil (soil:water ratio 1:3), but only in the most dilute slurry of topsoil (soil:water ratio 1:100). Our results demonstrate that protozoan predation in soil slurries may compromise quantification of contaminant mineralization potential, especially when the initial density of degrader bacteria is low and their growth is controlled by predation during the incubation period.
authors: Department of Geochemistry, Geological Survey of Denmark and Greenland, Copenhagen K, Denmark. nba@geus.dk
authors: Nora
authors: N
authors: Badawi
authors: Anders R
authors: AR
authors: Johnsen
authors: Kristian K
authors: KK
authors: Brandt
authors: Jan
authors: J
authors: Sørensen
authors: Jens
authors: J
authors: Aamand
mesh_terms: D008456:2-Methyl-4-chlorophenoxyacetic Acid / Q000032:analysis* / Q000378:metabolism; D001419:Bacteria / Q000254:growth & development; D001673:Biodegradation, Environmental; D004784:Environmental Monitoring; D056890:Eukaryota / Q000502:physiology; D006540:Herbicides / Q000032:analysis* / Q000378:metabolism; D012987:Soil; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000032:analysis* / Q000378:metabolism
chemical_list: D006540:Herbicides; D012987:Soil; D012989:Soil Pollutants; D008456:2-Methyl-4-chlorophenoxyacetic Acid