User Manual Privacy Policy Disclaimer Contact us
  Advanced SearchBrowse




Journal Article

Isolation of heterotrophic diazotrophic bacteria from estuarine surface waters


Harder,  J.
Department of Microbiology, Max Planck Institute for Marine Microbiology, Max Planck Society;

There are no locators available
Fulltext (public)
There are no public fulltexts available
Supplementary Material (public)
There is no public supplementary material available

Farnelid, H., Harder, J., Bentzon-Tilia, M., & Riemann, L. (2014). Isolation of heterotrophic diazotrophic bacteria from estuarine surface waters. Environmental Microbiology, 16(10 Sp. Iss. SI), 3072-3082.

Cite as: http://hdl.handle.net/21.11116/0000-0001-C502-E
The wide distribution of diverse nitrogenase (nifH) genes affiliated with those of heterotrophic bacteria in marine and estuarine waters indicates ubiquity and an ecologically relevant role for heterotrophic N-2-fixers (diazotrophs) in aquatic nitrogen (N) cycling. However, the lack of cultivated representatives currently precludes an evaluation of their N-2-fixing capacity. In this study, microoxic or anoxic N-free media were inoculated with estuarine Baltic Sea surface water to select for N-2-fixers. After visible growth and isolation of single colonies on oxic plates or in anoxic agar tubes, nifH gene amplicons were obtained from 64 strains and nitrogenase activity, applying the acetylene reduction assay, was confirmed for 40 strains. Two strains, one Gammaproteobacterium affiliated with Pseudomonas and one Alphaproteobacterium affiliated with Rhodopseudomonas were shown to represent established members of the indigenous diazotrophic community in the Baltic Sea, with abundances of up to 7.9x10(4) and 4.7x10(4)nifH copies l(-1) respectively. This study reports media for successful isolation of heterotrophic diazotrophs. The applied methodology and the obtained strains will facilitate future identification of factors controlling heterotrophic diazotrophic activity in aquatic environments, which is a prerequisite for understanding and evaluating their ecology and contribution to N cycling at local and regional scales.