Phages in Marine Ecology
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Marine plankton is a mixture of photosynthesizing bacteria,
eucaryotic phytoplankton, and other bacteria and microorganisms.
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It is the base of the oceanic food chain, and contributes
significantly to global oxygen production and the oceanic carbon sink.
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Microscopic examination of marine surface plankton indicates
5-10
times more phage particles than bacteria.
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Only a few marine bacteriophages have been cultured and characterized.
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One model of the marine plankton ecosystem holds:
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Lytic phages kill off their target species down to low concentrations
(< 103/ml, ~15% infected at any
time).
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At this level, the time to find a target bacteria comes to
equilibrium with the survival time of the phages. (~5% mortality/hr. due
to UV damage).
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This would exert a diversifying effect on the bacterial community
(meaning a little of many different species instead of a lot of one species).
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One would expect a coadaptive struggle
wherein bacteria evolve to escape their phages and the phages evolve to
catch up.
Phages in Soil Ecology:
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There is a complex food web of micro-organisms in soil engaged
in decomposing organic materials to
a form that supports plant growth.
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There are more phages than bacteria in environmental samples.
References:
Wilhelm
and Suttle, 1999.
Chibani-Chennoufi
et al., 2004.
Special
issue of Science on Soil., 2004.