Spatial and temporal variability of aerobic anoxygenic photoheterotrophic bacteria along the east coast of Australia

Abstract

Aerobic Anoxygenic Phototrophic Bacteria (AAnPB) are ecologically important microorganisms, widespread in oceanic photic zones. However, the key environmental drivers underpinning AAnPB abundance and diversity are still largely undefined. The temporal patterns in AAnPB dynamics at three oceanographic reference stations spanning at approximately 15° latitude along the Australian east coast were examined. AAnPB abundance was highly variable, with pufM gene copies ranging from 1.1 × 10 to 1.4 × 10 ml and positively correlated with day length and solar radiation. pufM gene Miseq sequencing revealed that the majority of sequences were closely related to those obtained previously, suggesting that key AAnPB groups are widely distributed across similar environments globally. Temperature was a major structuring factor for AAnPB assemblages across large spatial scales, correlating positively with richness and Gammaproteobacteria (phylogroup K) abundance but negatively with Roseobacter-clade (phylogroup E) abundance, with temperatures between 16°C and 18°C identified as a potential transition zone between these groups. Network analysis revealed that discrete AAnPB populations exploit specific niches defined by varying temperature, light and nutrient conditions in the Tasman Sea system, with evidence for both niche sharing and partitioning amongst closely related operational taxonomic units.

Biogeographic patterns of aerobic anoxygenic phototrophic bacteria reveal an ecological consistency of phylogenetic clades in different oceanic biomes

“…In line with Bibiloni-Isaksson et al . 17 , this result could reinforce the idea that key AAP bacterial groups are widely distributed across similar environments.…”

“…Indeed, (i) most pufM sequences identified from newly explored ecosystems, including some isolated and extreme environments, are similar to sequences retrieved elsewhere ( e.g . refs 17 , 18 , 20 ), (ii) next generation sequencing approaches such as 454 pyrosequencing 19 , 25 or Illumina MiSeq amplicon 17 did not yield a significant higher number of OTUs than classical clone library methods ( e.g . refs 15 , 16 , 26 ).…”

“…refs 17 , 18 , 20 ) and from high-throughput sequencing approaches to achieve pufM gene polymorphism ( e.g . refs 17 , 19 , 25 ) question the actual extent of the diversity but also the existence of biogeographical patterns for AAP bacteria in marine systems. Indeed, (i) most pufM sequences identified from newly explored ecosystems, including some isolated and extreme environments, are similar to sequences retrieved elsewhere ( e.g .…”

“…Most studies hypothesized that multifactorial parameters, such as geographic distance ( e.g . refs 16 , 17 ) and environmental gradients ( e.g . refs 15 , 18 – 20 ) act in structuring AAP populations, but the respective importance of these factors has not really been explored.…”

Distribution of Aerobic Anoxygenic Phototrophs in Freshwater Plateau Lakes

“…Result showed that free-living AAP bacteria were separately 2.3 (±0.69) × 10 6 cells mL -1 in Lake Taihu and 1.3 (±0.29) × 10 5 cells mL -1 in Lake Chaohu, which was higher than the previously reported levels in other eutrophic freshwater bodies [14]. The abundance of AAP bacteria was highly variable with copies of puf M gene ranging from 1.1 × 10 2 to 1.4 × 10 5 mL -1 [21] and 0.3 to 12.04 × 10 5 cells mL −1 in the surface layers of peat-bog lakes by epifluorescence microscopy numbering [13].…”