Isolation and characterization of aerobic anoxygenic phototrophs from exposed soils from the Sør Rondane Mountains, East Antarctica

Abstract

This study investigated the culturable aerobic phototrophic bacteria present in soil samples collected in the proximity of the Belgian Princess Elisabeth Station in the Sør Rondane Mountains, East Antarctica. Until recently, only oxygenic phototrophic bacteria (Cyanobacteria) were well known from Antarctic soils. However, more recent non-cultivation-based studies have demonstrated the presence of anoxygenic phototrophs and, particularly, aerobic anoxygenic phototrophic bacteria in these areas. Approximately 1000 isolates obtained after prolonged incubation under different growth conditions were studied and characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Representative strains were identified by sequence analysis of 16S rRNA genes. More than half of the isolates grouped among known aerobic anoxygenic phototrophic taxa, particularly with Sphingomonadaceae, Methylobacterium and Brevundimonas. In addition, a total of 330 isolates were tested for the presence of key phototrophy genes. While rhodopsin genes were not detected, multiple isolates possessed key genes of the bacteriochlorophyll synthesis pathway. The majority of these potential aerobic anoxygenic phototrophic strains grouped with Alphaproteobacteria (Sphingomonas, Methylobacterium, Brevundimonas and Polymorphobacter).

How environment selects: Resilience and survival of microbial mat community within intermittent karst spring Krčić (Croatia)

“…Pseudomonas (Gammaproteobacteria), found in higher numbers during this winter condition, are known to be able to survive in cold environments with adaptation including activation of specific metabolic pathways (Tribelli & López, 2018 and Pseudomonas (Gammaproteobacteria). Interestingly, some of these bacteria were found as members of soil microbial community of the Antarctica ice-free regions (Tahon & Willems, 2017). As stated in this research, in the conditions of oligotrophy and strong solar radiation, aerobic anoxygenic phototrophic bacterial groups are those adopted to use sunlight and convert it into chemical energy in order to support life.…”

“…In addition, new genera were enriched within Proteobacteria: Polymorphobacter genera (Alphaproteobacteria), Polaromonas and Massilia (Betaproteobacteria) , and Pseudomonas (Gammaproteobacteria). Interestingly, some of these bacteria were found as members of soil microbial community of the Antarctica ice‐free regions (Tahon & Willems, ). As stated in this research, in the conditions of oligotrophy and strong solar radiation, aerobic anoxygenic phototrophic bacterial groups are those adopted to use sunlight and convert it into chemical energy in order to support life.…”

“…This suggested the potential presence of novel species and metabolic traits in this habitat. Due to conditions similar to those in higher altitude (dryness, strong UV radiation, and low concentration of organic materials), it was not surprising to find Polaromonas and Polymorphobacter genera, found in unvegetated periglacial soils in high‐elevated environments and ice‐free polar regions (Darcy, Lynch, King, Robeson & Schmidt, ; Tahon & Willems, ). Polaromonas is a metabolically diverse “opportunitroph” capable of taking advantage of transient periods of higher temperatures and substrate availability for development (Darcy et al, ).…”

“…Polaromonas and Polymorphobacter genera, found in unvegetated periglacial soils in high-elevated environments and ice-free polar regions (Darcy, Lynch, King, Robeson & Schmidt, 2016;Tahon & Willems, 2017).…”

The influence of substrate concentration on the culturability of heterotrophic soil microbes isolated by high-throughput dilution-to-extinction cultivation

“…The second lineage-Frankiales sp. strains 188 AZCC_0102 and AZCC_0072-classified as members of the Frankiales order of the 189 Actinobacteria class with best matches of <97% nucleotide identity to existing Frankiales 190 isolates (42). 191…”