Distribution of Aerobic Anoxygenic Phototrophs in Freshwater Plateau Lakes

Abstract

Aerobic anoxygenic phototrophic (AAP) bacteria are photoheterotrophs that use both organic substrates and solar light for carbon and energy requirements. The prevalence of AAP bacteria and their functional role in biogeochemical cycles were numerously reported in ocean habitats [1][2][3][4]. In most studies, they were defined as an important contributor to the carbon cycle. AAP bacteria could be approximately <1% to 10% of total bacteria in the euphotic zones of marine environments [1,[4][5][6]. The cell size of AAP bacteria was significantly larger than Pol. J. Environ. Stud. Vol. 27, No. 2 (2018), 871-879 AbstractAerobic 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.

Abundance and Spatial Distribution of Aerobic Anoxygenic Phototrophic Bacteria in Tama River, Japan

“…The abundances of cyanobacteria ranged from under the detection limit to 3.2 × 10 4 cells mL −1 at the four sites (Figure 2c) and were the highest at the site FS like AAnPB. The free-living AAnPB accounted for 6.1%-19.6% of the total bacterial abundance (Figure 2d), which was within the ranges reported in the previous studies on lakes and ponds [8][9][10][11][12][13][14][15]. The cyanobacteria accounted for 0.8%-12.8% of the total bacteria (Figure 2e).…”

“…Some previous reports showed that AAnPB contributed profoundly to the carbon stock and cycle in the ocean [3,5,7]. In lakes and ponds, AAnPB were also frequently observed albeit with the wide variation in relative abundance (i.e., 1%-37% of the total bacteria) [8][9][10][11][12][13][14][15] and could make the contribution in the freshwater systems as well. However, in contrast to those in marine environments, the abundance and spatial distribution of AAnPB in the freshwater environments, especially rivers, remain poorly understood.…”

Diversity of Aerobic Anoxygenic Phototrophs and Rhodopsin-Containing Bacteria in the Surface Microlayer, Water Column and Epilithic Biofilms of Lake Baikal

“…The taxonomic composition of AAP communities in Lake Baikal is similar to that in other freshwater bodies [ 14 , 15 , 16 , 18 , 22 , 88 , 89 ]. As in Lake Baikal, Rhodobacterales and Burkholderiales dominated, and Rhizobiales, Rhodospirillales, and Sphingomonadales were detected almost in every studied water body.…”

“…To date, the AAPs detected in different freshwater lakes and rivers belong to the class Alphaproteobacteria, orders Rhodospirillales, Rhodobacterales, Sphingomonadales, Rhizobiales, and Caulobacterales [ 10 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ], as well as the class Betaproteobacteria, including genera Limnohabitans [ 16 , 18 , 19 , 21 ] and Polynucleobacter [ 22 ]. Additionally, the bacteria of phyla Gemmatimonadetes [ 23 ] and Firmicutes (Lactobacillales) [ 18 ] were reported. In contrast to marine ecosystems, Gammaproteobacteria are rare in freshwater bodies [ 10 , 22 ].…”

Photosynthesis, carbon acquisition and primary productivity of phytoplankton: a review dedicated to Colin Reynolds

“…Moreover, aerobic anoxygenic phototrophic bacteria (AAP) have been detected in several inland waters (Mašín et al, 2008;Ferrera et al, 2017;Tian et al, 2018). These organisms represent a functional group belonging to Alpha-Beta-and Gammaproteobacteria, are obligate aerobic and photoheterotrophic.…”