Distribution of Aerobic Anoxygenic Phototrophs in Freshwater Plateau Lakes.

Aerobic anoxygenic phototrophic (AAP) bacteria are known functionally as photoheterotrophic microbes. Though numerously reported from ocean habitats, their distribution in freshwater lakes is far less documented. In the present study we investigated the dynamics of AAP bacteria in freshwater plateau lakes. Results revealed a high abundance of AAP bacteria in eutrophic lakes. Moreover, AAP bacteria were positively correlated with TN, TP, and Chl a, but the variations of AAP bacterial proportion to potential total bacteria (AAPB%). Alphaproteobacteria-related sequences dominated lakes Luguhu, Erhai, and Chenghai at ratios of 93.9, 85.4, and 70.6%, respectively, and in total comprised eight clearly defined subgroups. Sequences affiliated with Beta- and Grammaproteobacteria were found to be rare taxa. Additionally, Alkalibacterium-like sequences belonging to Firmutes were assigned. Overall, sequences from Alpha-, Beta-, Gammaproteobacteria, and Firmutes separately comprised of 81.6, 8.8, 0.8, and 4.0%. Our present work revealed extreme dynamics of AAP bacteria in both water columns and non-euphotic sediments of plateau aquatic ecosystems, which consolidated their wide distribution and enhanced adaptation. [ABSTRACT FROM AUTHOR]