@article{TittelWiehleWannickeetal.2009,
  author    = {Tittel, Joerg and Wiehle, Ines and Wannicke, Nicola and Kampe, Heike and Poerschmann, Juergen and Meier, Jutta and Kamjunke, Norbert},
  title     = {Utilisation of terrestrial carbon by osmotrophic algae},
  issn      = {1015-1621},
  doi       = {10.1007/s00027-008-8121-2},
  year      = {2009},
  abstract  = {Terrestrial-derived dissolved organic carbon (DOC) contributes significantly to the energetic basis of many aquatic food webs. Although heterotrophic bacteria are generally considered to be the sole consumers of DOC, algae and cyanobacteria of various taxonomic groups are also capable of exploiting this resource. We tested the hypothesis that algae can utilise DOC in the presence of bacteria if organic resources are supplied in intervals by photolysis of recalcitrant DOC. In short-term uptake experiments, we changed irradiation in the range of minutes. As model substrates, polymers of radiolabelled coumaric acid (PCA) were used, which during photolysis are known to release aromatic compounds comparable to terrestrial-derived and refractory DOC. Three cultured freshwater algae readily assimilated PCA photoproducts equivalent to a biomass-specific uptake of 5-60\% of the bacterial competitors present. Algal substrate acquisition did not depend on whether PCA was photolysed continuously or in intervals. However, the data show that photoproducts of terrestrial DOC can be a significant resource for osmotrophic algae. In long-term growth experiments, interval light was applied one hour per day. We allowed cultured Chlamydomonas to compete for ambient DOC of low concentration. We found higher abundances of Chlamydomonas when cultures were irradiated intermittently rather than continuously. These data suggest that photolysis of DOC supports algal heterotrophy, and potentially facilitates growth, when light fluctuations are large, as during the diurnal light cycle. We concluded that osmotrophic algae can efficiently convert terrestrial carbon into the biomass of larger organisms of aquatic food webs.},
  language  = {en}
}
@article{AttermeyerTittelAllgaieretal.2015,
  author    = {Attermeyer, Katrin and Tittel, Joerg and Allgaier, Martin and Frindte, Katharina and Wurzbacher, Christian and Hilt, Sabine and Kamjunke, Norbert and Grossart, Hans-Peter},
  title     = {Effects of Light and Autochthonous Carbon Additions on Microbial Turnover of Allochthonous Organic Carbon and Community Composition},
  series = {Microbial ecology},
  volume    = {69},
  journal   = {Microbial ecology},
  number    = {2},
  publisher = {Springer},
  address   = {New York},
  issn      = {0095-3628},
  doi       = {10.1007/s00248-014-0549-4},
  pages     = {361 -- 371},
  year      = {2015},
  abstract  = {The fate of allochthonous dissolved organic carbon (DOC) in aquatic systems is primarily controlled by the turnover of heterotrophic bacteria. However, the roles that abiotic and biotic factors such as light and DOC release by aquatic primary producers play in the microbial decomposition of allochthonous DOC is not well understood. We therefore tested if light and autochthonous DOC additions would increase allochthonous DOC decomposition rates and change bacterial growth efficiencies and community composition (BCC). We established continuous growth cultures with different inocula of natural bacterial communities and alder leaf leachates (DOCleaf) with and without light exposure before amendment. Furthermore, we incubated DOCleaf together with autochthonous DOC from lysed phytoplankton cultures (DOCphyto). Our results revealed that pretreatments of DOCleaf with light resulted in a doubling of bacterial growth efficiency (BGE), whereas additions of DOCphyto or combined additions of DOCphyto and light had no effect on BGE. The change in BGE was not accompanied by shifts in the phylogenetic structure of the BCC, but BCC was influenced by the DOC source. Our results highlight that a doubling of BGE is not necessarily accompanied by a shift in BCC and that BCC is more strongly affected by resource properties.},
  language  = {en}
}