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Aquatic Microbial Ecology

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AME 60:203-213 (2010)  -  DOI:

Relationships between bacteria and heterotrophic nanoflagellates in lake water examined by different techniques controlling grazing pressure

Tomasz Adamczewski1, Ryszard J. Chróst1,*, Krystyna Kalinowska2, Agnieszka Skowroñska3,4

1Department of Microbial Ecology, Institute of Botany, Faculty of Biology, University of Warsaw, Miecznikowa 1,
02-096 Warsaw, Poland
2Hydrobiological Station, Centre for Ecological Research, Polish Academy of Sciences, Lesna 13, 11-730 Mikolajki, Poland
3Department of Environmental Microbiology, Faculty of Science and Fisheries, University of Warmia and Mazury, Prawocheñskiego 1, 10-957 Olsztyn-Kortowo, Poland
4Present address: Department of Human Physiology, Faculty of Medicine, University of Warmia and Mazury, Olsztyn, Poland
*Corresponding author. Email:

ABSTRACT: A dialysis bags experiment, involving the use of natural water from eutrophic Lake Mikolajskie (Mazurian Lake District, Poland), was performed to assess the impact of grazing pressure by heterotrophic nanoflagellates (HNF; <10 µm) on bacterial abundance, their size distribution, taxonomic composition and activity measured by bacterial secondary production (BP) and the contribution of active bacteria with an intact membrane (MEM+). Three different techniques—size-fractionation (<1.0 µm pore size), dilution (10×) and selective eukaryotic inhibition (cycloheximide and colchicine)—were applied to control HNF grazing. There were significant differences in the effectiveness of grazing pressure limitation between the different techniques employed. The most distinct changes in the bacterial community were found in the control and the 10× diluted treatments; in both, a considerable increase in HNF abundance was noted. In these 2 treatments, a significant decrease in both bacterial numbers and contribution of MEM+ cells, as well as an increase in the proportion of bacterial filaments (up to 50 µm long), was observed. In contrast, the use of cycloheximide and colchicine in combination resulted in the lowest and an almost constant HNF abundance. In addition, high numbers of bacteria with a large proportion of MEM+ cells (30 to 40%) and exponential increase of bacterial secondary production were found. These results suggest that eukaryotic inhibition is the most useful method of limiting HNF grazing pressure and involves minimal manipulation of the water sample. Close relationships between bacteria and HNF confirm the crucial role of nanoflagellates in shaping bacterial abundance, morphology and activity.

KEY WORDS: Bacteria · HNF · Grazing pressure · Dialysis bags · Filtration · Dilution · Eukaryotic inhibition

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Cite this article as: Adamczewski T, Chróst RJ, Kalinowska K, Skowroñska A (2010) Relationships between bacteria and heterotrophic nanoflagellates in lake water examined by different techniques controlling grazing pressure. Aquat Microb Ecol 60:203-213.

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