CO2 assimilation strategies in stratified lakes: Diversity and distribution patterns of chemolithoautotrophs.

Albin Alfreider,Monika Summerer,Andreas Baumer,Teresa Bogensperger,Thomas Posch,Michaela M Salcher

doi:10.1111/1462-2920.13786

Albin Alfreider, Monika Summerer + Show 4 more

Open Access

https://doi.org/10.1111/1462-2920.13786

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Abstract

SummaryWhile mechanisms of different carbon dioxide (CO2) assimilation pathways in chemolithoautotrohic prokaryotes are well understood for many isolates under laboratory conditions, the ecological significance of diverse CO2 fixation strategies in the environment is mostly unexplored. Six stratified freshwater lakes were chosen to study the distribution and diversity of the Calvin-Benson-Bassham (CBB) cycle, the reductive tricarboxylic acid (rTCA) cycle, and the recently discovered archaeal 3-hydroxypropionate/4-hydroxybutyrate (HP/HB) pathway. Eleven primer sets were used to amplify and sequence genes coding for selected key enzymes in the three pathways. Whereas the CBB pathway with different forms of RubisCO (IA, IC and II) was ubiquitous and related to diverse bacterial taxa, encompassing a wide range of potential physiologies, the rTCA cycle in Epsilonproteobacteria and Chloribi was exclusively detected in anoxic water layers. Nitrifiying Nitrosospira and Thaumarchaeota, using the rTCA and HP/HB cycle respectively, are important residents in the aphotic and (micro-)oxic zone of deep lakes. Both taxa were of minor importance in surface waters and in smaller lakes characterized by an anoxic hypolimnion. Overall, this study provides a first insight on how different CO2 fixation strategies and chemical gradients in lakes are associated to the distribution of chemoautotrophic prokaryotes with different functional traits.

Highlights

While mechanisms of different carbon dioxide (CO2 ) assimilation pathways in chemolithoautotrohic prokaryotes are well understood for many isolates under laboratory conditions, the ecological significance of diverse CO2 fixation strategies in the environment is mostly unexplored
A major effort was undertaken toevaluate already published PCR-based marker systems and to design and test new primer pairs before they were applied on a routine basis at our study sites
Kato et al (2012) designed a PCR primer set targeting RubisCO form II gene where the coverage was reported to be superior compared with the primers designed by Alfreider et al (2003)

Summary

Introduction

While mechanisms of different carbon dioxide (CO2 ) assimilation pathways in chemolithoautotrohic prokaryotes are well understood for many isolates under laboratory conditions, the ecological significance of diverse CO2 fixation strategies in the environment is mostly unexplored. Published at: Alfreider, Albin; Baumer, Andreas; Bogensperger, Teresa; Posch, Thomas; Salcher, Michaela M; Summerer, Monika (2017). A major effort was undertaken to (re)evaluate already published PCR-based marker systems and to design and test new primer pairs before they were applied on a routine basis at our study sites.

Results

Conclusion