@article{CornoSalkaPohlmannetal.2015,
  author    = {Corno, Gianluca and Salka, Ivette and Pohlmann, Kirsten and Hall, Alex R. and Grossart, Hans-Peter},
  title     = {Interspecific interactions drive chitin and cellulose degradation by aquatic microorganisms},
  series = {Aquatic microbial ecology : international journal},
  volume    = {76},
  journal   = {Aquatic microbial ecology : international journal},
  number    = {1},
  publisher = {Institute of Mathematical Statistics},
  address   = {Oldendorf Luhe},
  issn      = {0948-3055},
  doi       = {10.3354/ame01765},
  pages     = {27 -- +},
  year      = {2015},
  abstract  = {Complex biopolymers (BPs) such as chitin and cellulose provide the majority of organic carbon in aquatic ecosystems, but the mechanisms by which communities of bacteria in natural systems exploit them are unclear. Previous degradation experiments in artificial systems predominantly used microcosms containing a single bacterial species, neglecting effects of interspecific interactions. By constructing simplified aquatic microbial communities, we tested how the addition of other bacterial species, of a nanoflagellate protist capable of consuming bacteria, or of both, affect utilization of BPs. Surprisingly, total abundance of resident bacteria in mixed communities increased upon addition of the protist. Concomitantly, bacteria shifted from free-living to aggregated morphotypes that seemed to promote utilization of BPs. In our model system, these interactions significantly increased productivity in terms of overall bacterial numbers and carbon transfer efficiency. This indicates that interactions on microbial aggregates may be crucial for chitin and cellulose degradation. We therefore suggest that interspecific microbial interactions must be considered when attempting to model the turnover of the vast pool of complex biopolymers in aquatic ecosystems.},
  language  = {en}
}
@article{KleebergHupferGustetal.2013,
  author    = {Kleeberg, Andreas and Hupfer, Michael and Gust, Giselher and Salka, Ivette and Pohlmann, Kirsten and Grossart, Hans-Peter},
  title     = {Intermittent riverine resuspension effects on phosphorus transformations and heterotrophic bacteria},
  series = {Limnology and oceanography},
  volume    = {58},
  journal   = {Limnology and oceanography},
  number    = {2},
  publisher = {Wiley},
  address   = {Waco},
  issn      = {0024-3590},
  doi       = {10.4319/lo.2013.58.2.0635},
  pages     = {635 -- 652},
  year      = {2013},
  abstract  = {Intermittent riverine resuspension (IRR), a common phenomenon, was applied to investigate its effects on sedimentary resources availability and bacteria in the water column. This lab experiment used organic-rich lowland river sediment in a newly designed erosion chamber, the Benthic Water Column Simulator, generating well-defined ratios of shear velocity u* to turbulence intensity. Eight consecutive resuspension events, 1-8, were initiated at u* = 1.1 cm s(-1). Sedimentary and phosphorus entrainment decreased from 20.4 g m(-2) h(-1) and 111.6 mg m(-2) h(-1) at event 1 to 1.31 g m(-2) h(-1) and 18.7 mg m(-2) h(-1) at event 8, suggesting an exhaustion of particulate and dissolved sediment constituents. Entrainment of particle-associated (PA) bacteria (132.7 x 10(9)-251.1 x 10(9) cells m(-2) h(-1)) was strongly correlated to that of particles. Free-living (FL) bacteria (-27.6 x 10(9)-36.4 x 10(9) cells m(-2) h(-1)) were fractionally entrained. Numbers of PA bacteria remained low after each event, whereas those of FL bacteria strongly increased 5-15 h after an event because of growth due to increased availability of dissolved organic carbon and inorganic nutrients following each event. FL bacteria community structure also changed during IRR. The systematic changes over consecutive IRR cycles show a strong effect in all considered parameters that elude the typical single-event, steady-state experiments. IRR should thus be considered in two respects: experimental protocols on riverine water quality should be revised. In ecosystem modeling, IRR should be considered to better predict extent and effect of resuspension. Only IRR adequately reflects the natural interplay between hydrodynamics and organisms in rivers.},
  language  = {en}
}