title: The engineering potential of natural benthic bacterial assemblages in terms of the erosion resistance of sediments.
abstract: The secretion of extracellular polymeric substances (EPS) by bacteria has been recognized as important across a wide range of scientific disciplines, but in natural sediments, EPS production by microalgae as a mechanism of sediment stabilization has received much more attention than bacterial products. In the present study, the stabilization potential of a natural benthic bacterial assemblage was tested in cultures growing on noncohesive glass beads. The surface erosion resistance as determined by a cohesive strength meter was significantly enhanced over time compared with controls. Nutrient enrichment of the bacterial assemblages by a general broth (bacteria+) resulted in enhanced stabilization (x 3.6) compared with nutrient-depleted (bacteria) assemblages (x 1.8). This correlated with higher bacterial biomass and EPS concentrations in enriched cultures. Substratum stability was closely related to bacterial cell numbers (R2=0.75/0.78) and EPS protein concentrations (R2=0.96/0.53) (for bacteria/bacteria+ treatments, respectively), but not to EPS carbohydrates. This study implies a greater significance of extracellular proteins in substratum cohesion within the EPS complex than recognized previously. The data show both the importance of bacterial assemblages for microbial sediment stabilization and that a change in abiotic conditions can significantly affect sediment stabilization.
authors.affiliation: Sediment Ecology Research Group, Gatty Marine Laboratory, University of St Andrews, Scotland, UK. sug@st-andrews.ac.uk
authors.forename: Sabine Ulrike
authors.initials: SU
authors.lastname: Gerbersdorf
authors.forename: Werner
authors.initials: W
authors.lastname: Manz
authors.forename: David M
authors.initials: DM
authors.lastname: Paterson
mesh_terms: D001419:Bacteria / Q000254:growth & development* / Q000378:metabolism / Q000648:ultrastructure; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000032:analysis; D018533:Biomass; D002241:Carbohydrates / Q000032:analysis; D015169:Colony Count, Microbial; D003470:Culture Media; D005618:Fresh Water / Q000032:analysis / Q000382:microbiology; D019015:Geologic Sediments / Q000032:analysis / Q000382:microbiology*; D005898:Glass; D008855:Microscopy, Electron, Scanning; D011108:Polymers / Q000737:chemistry / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D002241:Carbohydrates; D003470:Culture Media; D011108:Polymers