Microbial reduction of Fe(III) and turnover of acetate in Hawaiian soils.

Beitrag in einer Fachzeitschrift


Details zur Publikation

Autor(en): Bäumler R
Zeitschrift: Fems Microbiology Ecology
Verlag: Wiley-Blackwell
Jahr der Veröffentlichung: 2002
Band: 40
Heftnummer: 1
Seitenbereich: 73-81
ISSN: 0168-6496
Sprache: Englisch


Abstract


Soils contain anoxic microzones, and acetate is an intermediate during the turnover of soil organic carbon. Due to negligible methanogenic activities in well-drained soils, acetate accumulates under experimentally imposed short-term anoxic conditions. In contrast to forest, agricultural, and prairie soils, grassland soils from Hawaii rapidly consumed rather than formed acetate when incubated under anoxic conditions. Thus, alternative electron acceptors that might be linked to the anaerobic oxidation of soil organic carbon in Hawaiian soils were assessed. Under anoxic conditions, high amounts of Fe(II) were formed by Hawaiian soils as soon as soils were depleted of nitrate. Rates of Fe(II) formation for different soils ranged from 0.01 to 0.31 μmol (g dry weight soil)-1 h-1, but were not positively correlated to increasing amounts of poorly crystallized iron oxides. In general, sulfate-reducing and methanogenic activities were negligible. Supplemental acetate was rapidly oxidized to CO2 via the sequential reduction of nitrate and Fe(III) in grassland soil (obtained near Kaena State Park). Supplemental H2 stimulated the formation of Fe(II), but H2-utilizing acetogens appeared to also be involved in the consumption of H2. Approximately 270 μmol Fe(III) (g dry weight soil)-1 was available for Fe(III)-reducing bacteria, and acetate became a stable end product when Fe(III) was depleted in long-term incubations. Most-probable-number estimates of H2- and acetate-utilizing Fe(III) reducers and of H2-utilizing acetogens were similar. These results indicate that (i) the microbial reduction of Fe(III) is an important electron-accepting process for the anaerobic oxidation of organic matter in Fe(III)-rich Hawaiian soils of volcanic origin, and (ii) acetate, formed by the combined activity of fermentative and acetogenic bacteria, is an important trophic link in anoxic microsites of these soils. © 2002 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.



FAU-Autoren / FAU-Herausgeber

Bäumler, Rupert Prof. Dr.
Professur für Geographie

Zuletzt aktualisiert 2018-09-08 um 06:38