Diversity of aerobic anoxygenic phototrophic bacteria in paddy soil and their response to elevated atmospheric CO₂

Abstract

SummaryAerobic anoxygenic phototrophic bacteria (AAnPB) are recognized as an important group driving the global carbon cycling. However, the diversity of AAnPB in terrestrial environment remains largely unknown as well as their responses to the elevated atmospheric CO2. By using culture‐independent techniques, the diversity of AAnPB in paddy soil and the changes in response to the rising atmospheric CO2 were investigated within China FACE (Free‐air CO2 enrichment) platform. There was a phylogenetically diverse AAnPB community with large population size residing in paddy soil. The community structure of AAnPB in bulk and rhizospheric soils stayed almost identical, while the population size was higher in rhizospheric [2.0–2.5 × 108 copy number of pufM genes g−1 dry weight soil (d.w.s.)] than that in bulk (0.7–0.8 × 108 g−1 d.w.s.) soils. Elevated atmospheric CO2 appeared to significantly stimulate AAnPB abundance (up to 1.4–1.5 × 108 g−1 d.w.s.) and result in a higher AAnPB percentage in total bacterial community (from 0.5% up to 1.5%) in bulk soil, whereas no significant effect was observed in rhizospheric soil. Our results would extend the functional ecotypes of AAnPB and indicate that environmental changes associated with the rising atmospheric CO2 might affect AAnPB community in paddy soil.

Diversity of Phototrophic Genes Suggests Multiple Bacteria May Be Able to Exploit Sunlight in Exposed Soils from the Sør Rondane Mountains, East Antarctica

“…The remainder of the PufM diversity in our samples, although recovered in small relative numbers, also mainly related to aquatic photoheterotrophic taxa. However, several of the PufM sequences recovered (e.g., Methylobacterium -like, Rhodopseudomonas -like) were highly similar to PufM reported from Arctic soils (Feng et al, 2014) or Chinese paddy soils (Feng et al, 2009, 2011a,b,c). Thus, although aerobic anoxygenic phototrophy is frequently studied in aquatic environments, our data strongly suggest that this lifestyle may potentially be important in terrestrial ecosystems.…”

“…Under these new atmospheric conditions, many of the anaerobic anoxygenic phototrophic bacteria may have disappeared from the now oxygenated habitats, although some groups adapted and embarked on an aerobic lifestyle (Koblížek, 2015). These aerobic anoxygenic phototrophic bacteria (AAP) were first reported in 1978 (Harashima et al, 1978) and are defined as aerobic species that synthesize bacteriochlorophyll and use light energy as an auxiliary energy source for their mostly heterotrophic metabolism (Feng et al, 2011a; Koblížek, 2015). Moreover, they do not contain carbon fixation enzymes (Yurkov and Csotonyi, 2009).…”

Effect of root exudates of Eucalyptus urophylla and Acacia mearnsii on soil microbes under simulated warming climate conditions

“…But interestingly, we not only found the negative indirect effects, but also found that elevated CO 2 could directly change the community structure of microorganism and significantly increased the microbial biomass of soil in both E. urophylla and A. mearnsii . Similarly, some studies found elevated CO 2 significantly increased the biomass of soil in non-rhizosphere soil or bulk soil [41, 42]. Although the exact mechanisms behind the direct effect are not well known, we believe that the ratio of gases in the atmosphere may cause the changes in soil surface moisture or soil respiration.…”

Distribution of Aerobic Anoxygenic Phototrophs in Freshwater Plateau Lakes

“…Recently, Gemmatimonas phototrophica was found to harbor a photosynthesis gene cluster of proteobacterial origin [34][35] and phototrophic Gemmatimonadetes bacteria consisting of 0.4-11.9% of whole phototrophic microbial communities in their habitats [36]. The habitats for AAP bacteria are as diverse as marine environments, freshwater lakes, saline lakes, soda lakes, and soils [37][38][39][40]. The complex interplay of local contemporary environmental effects and dispersal limitations contribute to the distribution of anoxygenic phototrophs.…”