title: Bacterial and fungal colonization and decomposition of submerged plant litter: consequences for biogenic silica dissolution.
abstract: We studied bacterial and fungal colonization of submerged plant litter, using a known Si-accumulator (Equisetum arvense), in experimental microcosms during one month. We specifically addressed the microbial decomposer role concerning biogenic silica (bSiO2) dissolution from the degrading litter. To vary the rates and level of microbial colonization, the litter was combined with a range of mineral nitrogen (N) and phosphorous (P) supplements. Overall microbial growth on plant litter increased with higher levels of N and P. There was a tendency for higher relative bacterial than fungal stimulation with higher nutrient levels. Differences in microbial colonization of litter between treatments allowed us to test how Si remineralization from plants was influenced by microbial litter decomposition. Contrary to previous results and expectations, we observed a general reduction in Si release from plant litter colonized by a microbial community, compared with sterile control treatments. This suggested that microbial growth resulted in a reduction of dissolved Si concentrations, and we discuss candidate mechanisms to explain this outcome. Hence, our results imply that the microbial role in plant litter associated Si turnover is different from that commonly assumed based on bSiO2 dissolution studies in aquatic ecosystems.
authors.affiliation: Department of Geology, Geocentrum II, Lund University, SE-223 62 Lund, Sweden; hanna_alfredsson@hotmail.com.
authors.forename: Hanna
authors.initials: H
authors.lastname: Alfredsson
authors.affiliation: Department of Geology, Geocentrum II, Lund University, SE-223 62 Lund, Sweden;
authors.forename: Wim
authors.initials: W
authors.lastname: Clymans
authors.affiliation: Department of Geology, Geocentrum II, Lund University, SE-223 62 Lund, Sweden;
authors.forename: Johanna
authors.initials: J
authors.lastname: Stadmark
authors.affiliation: Department of Geology, Geocentrum II, Lund University, SE-223 62 Lund, Sweden;
authors.forename: Daniel
authors.initials: D
authors.lastname: Conley
authors.affiliation: Department of Microbial Ecology, Ecology building, Lund University, SE-223 62 Lund, Sweden.
authors.forename: Johannes
authors.initials: J
authors.lastname: Rousk
mesh_terms: D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000254:growth & development* / Q000302:isolation & purification; D017753:Ecosystem; D005658:Fungi / Q000145:classification / Q000235:genetics / Q000254:growth & development* / Q000302:isolation & purification; D009584:Nitrogen / Q000032:analysis / Q000378:metabolism; D010944:Plants / Q000382:microbiology*; D012822:Silicon Dioxide / Q000737:chemistry; D012995:Solubility
chemical_list: D012822:Silicon Dioxide; D009584:Nitrogen
keywords: bacteria; dissolution; fungi; phytoliths; plant litter; remineralization; silica