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Aquatic Microbial Ecology

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AME 78:81-92 (2016)  -  DOI:

Rapid adaptation of predation resistance in bacteria isolated from a seawater microcosm

P. Mathisen1, J. Thelaus2, S. Sjöstedt de Luna3, A. Andersson1,*

1Dept. of Ecology and Environmental Science, Umeå University, 901 87 Umeå, Sweden
2Division of CBRN Defence and Security, FOI Swedish Defence Research Agency, 901 82 Umeå, Sweden
3Dept. of Mathematics and Mathematical Statistics, Umeå University, 901 87 Umeå, Sweden
*Corresponding author:

ABSTRACT: Bacterial defense against protozoan grazing has been shown to occur in many different bacteria. Predation resistance traits may however be plastic, making bacterial communities resilient or resistant to predation perturbations. We studied the adaptation of predation resistance traits in bacteria isolated from a microcosm experiment. In the initial microcosm experiment the predation pressure on bacteria varied markedly, while changes in the bacterial community composition could not be verified. Seven bacteria were isolated from the microcosm (Micrococcus sp., Rhodobacter sp., Paracoccus sp., Shewanella sp., Rhizobium sp. and 2 unidentified species) and these were repeatedly exposed to high predation by the ciliate Tetrahymena pyriformis. High variations in edibility and rate of adaptation of predation resistance traits were observed among the strains. The initial mortality rate of the different bacterial taxa and the change over time varied by a factor of 7 and 24, respectively. Rhodobacter sp. was already predation resistant at the start of the experiment and did not change much over time, while Micrococcus sp., Paracoccus sp. and Shewanella sp. initially were relatively edible and later developed predation resistance. In conclusion, we show that rapid adaptation of predation resistance traits is common among bacteria in an aquatic microbial community, and that a single test of a bacterium’s edibility will in many cases not be enough to fully understand its ecological role, as it will not reveal the potential adaptive response. The results suggest the potential of rapid changes of predation resistance as a mechanism for bacterial communities to be resilient to variations in predation disturbances.

KEY WORDS: Bacterial isolates · Predation pressure · Predation resistance · Inedible · Adaptation· Tetrahymena

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Cite this article as: Mathisen P, Thelaus J, Sjöstedt de Luna S, Andersson A (2016) Rapid adaptation of predation resistance in bacteria isolated from a seawater microcosm. Aquat Microb Ecol 78:81-92.

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