title: Stability of the total and functional microbial communities in river sediment mesocosms exposed to anthropogenic disturbances.
abstract: River systems are exposed to anthropogenic disturbances, including chemical pollution and eutrophication. This may affect the phylogenetic diversity as well as the abundance of various functional groups within sediment-associated microbial communities. To address such potential effects, mesocosms filled with Ebro delta sediment covered with river water were exposed to chlorinated organic compounds or to a high nutrient concentration as used for fertilization. Changes in the abundance of selected functional microbial groups, i.e. total aerobes, nitrate, sulfate and iron reducers, organohalide-respiring microorganisms as well as methanogens, were examined using culture-dependent most probable number and culture-independent PCR methods targeting phylogenetic as well as functional gene markers. It was concluded that the abundance of functional groups was neither affected by pollution with 1,2-dichloroethane and tetrachloroethene nor by elevated nutrient loads, although changes in the bacterial community composition were observed using 16S rRNA gene-targeted fingerprint techniques. This study reinforced the notion that complementary culture-dependent and molecular methods, focusing on different fractions of the microbial community (cultivable, active or total), should be used in combination for a comprehensive description of phylogenetic diversity and functional potential.
authors.affiliation: Deltares, Princetonlaan, Utrecht, The Netherlands. bas.vanderzaan@deltares.nl
authors.forename: Bas
authors.initials: B
authors.lastname: Van der Zaan
authors.forename: Hauke
authors.initials: H
authors.lastname: Smidt
authors.forename: Willem M
authors.initials: WM
authors.lastname: De Vos
authors.forename: Huub
authors.initials: H
authors.lastname: Rijnaarts
authors.forename: Jan
authors.initials: J
authors.lastname: Gerritse
mesh_terms: D001419:Bacteria / Q000145:classification* / Q000235:genetics; D058448:Biota; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000235:genetics; D005025:Ethylene Dichlorides / Q000032:analysis; D019015:Geologic Sediments / Q000382:microbiology*; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D045483:Rivers / Q000382:microbiology*; D013030:Spain; D013750:Tetrachloroethylene / Q000032:analysis; D014877:Water Pollution, Chemical
chemical_list: D004269:DNA, Bacterial; D005025:Ethylene Dichlorides; D012336:RNA, Ribosomal, 16S; C024565:ethylene dichloride; D013750:Tetrachloroethylene