Microbial Extracellular Polymeric Substances (EPS) in Fresh Water Sediments |
| |
Authors: | Sabine Ulrike Gerbersdorf Bernhard Westrich David M Paterson |
| |
Institution: | (1) Hydraulic Laboratory, Institute of Hydraulic Engineering, Universitaet Stuttgart, Pfaffenwaldring 61, Stuttgart, 70550, Germany;(2) Sediment Ecology Research Group, Gatty Marine Laboratory, University of St. Andrews, St. Andrews, KY16 8LB, Scotland, UK |
| |
Abstract: | Microbially produced extracellular polymeric substances (EPS) have been linked with many important ecological functions in
natural sediments; yet, most information has been derived from marine systems. The present paper is the first comprehensive
study on EPS (i.e., carbohydrates and proteins) dynamics in riverine sediments addressing spatial (six reservoirs and four
groyne fields across three European rivers), temporal (all seasons in 2003–2005), and vertical (over a 50-cm sediment depth
transect) pattern. The variation in hydrodynamic regime found in the reservoirs and groyne fields was reflected in the biomass
and composition of the benthic microorganisms that produce EPS. The microphytobenthic communities consisted mainly of diatoms
and a higher algal biomass (up to 248 μg g−1 dry weight, DW) seemed to be indicative for higher amounts of secreted colloidal carbohydrates. Consequently, the model proposed
by Underwood and Smith (1998) for the relation chlorophyll–colloidal carbohydrates was also applicable for upper riverine sediment layers. The close relation
between algal biomass and bacterial cell counts (108–109 cells g−1 DW) supports the idea of bacterial use of the secreted EPS. However, the data also suggest a contribution to the EPS pool
through bacterial secretion of proteins/extracellular enzymes and possibly carbohydrates. Over depth, the relationships between
microorganisms and EPS became increasingly decoupled along with increasing ratios of bound (refractory) to colloidal (labile)
EPS. These data suggest fresh production of polymeric substances in upper sediment layers and mainly accumulation of refractory,
biodegraded material in deeper layers. The high contents of EPS colloidal and bound carbohydrates (0.1–1.8 and 1.3–6.7 mg
g−1 DW, respectively) and EPS proteins (0.4–12.9 mg g−1 DW) at the freshwater study sites might indicate an important role in sediment ecology. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|