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- Eiler, Alexander, et al.
(författare)
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High Ratio of Bacteriochlorophyll Biosynthesis Genes to Chlorophyll Biosynthesis Genes in Bacteria of Humic Lakes
- 2009
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Ingår i: Applied and Environmental Microbiology. - 0099-2240 .- 1098-5336. ; 75:22, s. 7221-7228
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Tidskriftsartikel (refereegranskat)abstract
- Recent studies highlight the diversity and significance of marinephototrophic microorganisms such as picocyanobacteria, phototrophicpicoeukaryotes, and bacteriochlorophyll- and rhodopsin-holdingphototrophic bacteria. To assess if freshwater ecosystems alsoharbor similar phototroph diversity, genes involved in the biosynthesisof bacteriochlorophyll and chlorophyll were targeted to exploreoxygenic and aerobic anoxygenic phototroph composition in awide range of lakes. Partial dark-operative protochlorophyllideoxidoreductase (DPOR) and chlorophyllide oxidoreductase (COR)genes in bacteria of seven lakes with contrasting trophic statuseswere PCR amplified, cloned, and sequenced. Out of 61 sequencesencoding the L subunit of DPOR (L-DPOR), 22 clustered with aerobicanoxygenic photosynthetic bacteria, whereas 39 L-DPOR sequencesrelated to oxygenic phototrophs, like cyanobacteria, were observed.Phylogenetic analysis revealed clear separation of these freshwaterL-DPOR genes as well as 11 COR gene sequences from their marinecounterparts. Terminal restriction fragment length analysisof L-DPOR genes was used to characterize oxygenic aerobic andanoxygenic photosynthesizing populations in 20 lakes differingin physical and chemical characteristics. Significant differencesin L-DPOR community composition were observed between dystrophiclakes and all other systems, where a higher proportion of genesaffiliated with aerobic anoxygenic photosynthetic bacteria wasobserved than in other systems. Our results reveal a significantdiversity of phototrophic microorganisms in lakes and suggestniche partitioning of oxygenic and aerobic anoxygenic phototrophsin these systems in response to trophic status and coupled differencesin light regime.
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