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- Wikner, Johan, 1961-, et al.
(författare)
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Evidence for a tightly coupled nanoplanktonic predator-prey link regulating the bacterivores in the marine-environment
- 1988
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Ingår i: Marine Ecology Progress Series. - Oldenburg : Inter-Research. - 0171-8630 .- 1616-1599. ; 50:1-2, s. 137-145
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Tidskriftsartikel (refereegranskat)abstract
- A coupled predator-prey chain, starting with bactenvores, was invest~gated using the mlnicell recapture technique (MiniCap) Water samples were subjected to slze fract~onation wth decreasing filter pore sue in order to obtain a successive truncation of the microbial food chaln Our results showed that the malor bacterivores were flagellates in the size range of 1 to 3 pm The truncation of the food chain caused increased or decreased predation on the bactena, d e p e n d~n go n whether the bacterivores 'ivere released from or subjected to increased predat~on pressure We present a model describing trophic interactions between organisms less than 12 pm In size This model suggests 4 trophic levels to form a regulatory chain exer t~nga tight control on major bacterivores.
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- Wikner, Johan, 1961-, et al.
(författare)
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Use of genetically marked minicells as a probe in measurement of predation on bacteria in aquatic environments
- 1986
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Ingår i: Applied and Environmental Microbiology. - : American Society for Microbiology. - 0099-2240 .- 1098-5336. ; 52:1, s. 4-8
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Tidskriftsartikel (refereegranskat)abstract
- Minicells produced by Escherichia coli M2141 were used as probes to measure predation on pelagic bacteria in situ. The minicells, labeled with [35S]methionine in one specific protein, were shown to disappear in the presence of a microflagellate (Ochromonas sp.), as seen by a decrease in the amount of labeled marker protein with time. Incubation in filtered (pore size, 0.2 μm) and autoclaved seawater did not affect the amount of labeled marker protein in the minicell. The generation time of flagellates feeding on minicells was determined to be similar to that found for flagellates grown on seawater bacteria or living E. coli NC3. Data indicate that minicells are seen as true food particles by the flagellates. The minicell probe was used in recapture experiments, in which predation in situ on pelagic bacteria was demonstrated. The rate of bacterial production showed a clear covariation with the rate of predation, both in different sea areas and in depth profiles. The obtained results (11 field experiments) showed that the rate of predation, on average, accounts for the consumption of 62% of the bacteria produced.
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