Bacterial active community cycling in response to solar radiation and their influence on nutrient changes in a high altitude wetland

Frontiers in Microbiology

Vilma Pérez¹  Cristina Dorador¹  Chris Harrod²  Klaudia Hernandez³  Martha Hengst⁴  Veronica Molina⁶  Yoanna Eissler⁷ 

[1] Centre for Biotechnology and Bioengineering (CeBiB);Instituto de Ciencias Naturales Alexander von Humboldt;Universidad Andres Bello;Universidad Católica del Norte;Universidad de Antofagasta;Universidad de Playa Ancha;Universidad de Valparaíso;

关键词: Phototrophic bacteria;    solar radiation;    UVR;    PAR;    extreme ecosystem;    16S RNA gene pyrosequencing;   

DOI  :  10.3389/fmicb.2016.01823

来源: DOAJ

【 摘 要 】

Microbial communities inhabiting high altitude spring ecosystems are subjected to extreme changes in irradiation and temperature throughout the diel cycle. Here, using 16S rRNA gene tag pyrosequencing (cDNA) we determined the composition of actively transcribing bacteria from spring waters experimentally exposed through the day (morning, noon and afternoon) to variable levels of solar radiation and light quality, and evaluated their influence on nutrient recycling. Irradiation, temperature and changes in nutrient dynamics were associated with changes in the active bacterial community structure, predominantly by Cyanobacteria, Verrucomicrobia, Proteobacteria, and 35 other Phyla, including the recently described Candidate Phyla Radiation (e.g., Parcubacteria, Gracilibacteria, OP3, TM6, SR1). Diversity increased at noon, when the highest irradiances were measured (3.3 -3.9 H’, 1125 W m-2) compared to morning and afternoon (0.6-2.8 H’). This shift was associated with a decrease in the contribution to pyrolibraries by Cyanobacteria and an increase of Proteobacteria and other initially low frequently and rare bacteria phyla (<0.5%) in the pyrolibraries. A potential increase in the activity of Cyanobacteria and other phototrophic groups, e.g., Rhodobacterales, was observed and associated with UVR, suggesting the presence of photo-activated repair mechanisms to resist high levels of solar radiation. In addition, the percentage contribution of cyanobacterial sequences in the afternoon was similar to those recorded in the morning. The shifts in the contribution by Cyanobacteria also influenced the rate of change in nitrate, nitrite and phosphate, highlighted by a high level of nitrate accumulation during hours of high radiation and temperature associated with nitrifying bacteria activity. We did not detect ammonia or nitrite oxidizing bacteria in-situ, but both functional groups (Nitrosomona and Nitrospira) appeared mainly in pyrolibraries generated from dark incubations. In total, our results reveal that both the structure and the diversity of the active bacteria community was extremely dynamic through the day, and showed marked shifts in composition that influenced nutrient recycling, highlighting how abiotic variation affects potential ecosystem functioning.

【 授权许可】

Unknown