Aerobic Anoxygenic Phototrophic (AAP) bacteria are bacteriochlorophyll (BChl) a -containing organisms which use light energy to supplement their predominantly heterotrophic metabolism. Here, we investigated mortality and growth rates of AAP bacteria in three different freshwater lakes in Central Europe: the mountain lake Plešné, the oligo-mesotrophic Lake Stechlin and the forest pond Huntov. The mortality of AAP bacteria was estimated from diel changes of BChl a fluorescence. Net and gross growth rates were calculated from the increases in AAP cell numbers. The gross growth rates of AAP bacteria ranged from 0.38 to 5.6 d-1 , with the highest values observed during summer months. Simultaneously, the rapidly growing AAP cells have to cope with an intense grazing pressure by both zooplankton and protists. The presented results document that during the day, gross growth usually surpased mortality. Our results indicate that AAP bacteria utilize light energy under natural conditions to maintain rapid growth rates, which are balanced by a generally intense grazing pressure.

Biology Center CAS Institute of Hydrobiology Na Sádkách 702 7 České Budějovice 370 05 Czech Republic

Center Algatech Institute of Microbiology CAS Třeboň 37981 Czech Republic

Experimental Limnology Leibniz Institute of Freshwater Ecology and Inland Fisheries Stechlin 16775 Germany

Faculty of Science University of South Bohemia Branišovská 31 České Budějovice 370 05 Czech Republic

Inst for Biochemistry and Biology Potsdam University 14469 Potsdam Maulbeerallee 2 Germany

References provided by Crossref.org

Response of aerobic anoxygenic phototrophic bacteria to limitation and availability of organic carbon

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Photoheterotrophy by aerobic anoxygenic bacteria modulates carbon fluxes in a freshwater lake

Light and Primary Production Shape Bacterial Activity and Community Composition of Aerobic Anoxygenic Phototrophic Bacteria in a Microcosm Experiment

Diel changes and diversity of pufM expression in freshwater communities of anoxygenic phototrophic bacteria

Seasonal dynamics of aerobic anoxygenic phototrophs in freshwater lake Vlkov

Light enhances the growth rates of natural populations of aerobic anoxygenic phototrophic bacteria