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Identification of microbial populations driving biopolymer degradation in acidic peatlands by metatranscriptomic analysis
Author(s) -
Ivanova Anastasia A.,
Wegner CarlEric,
Kim Yongkyu,
Liesack Werner,
Dedysh Svetla.
Publication year - 2016
Publication title -
molecular ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.619
H-Index - 225
eISSN - 1365-294X
pISSN - 0962-1083
DOI - 10.1111/mec.13806
Subject(s) - acidobacteria , biology , archaea , stable isotope probing , ribosomal rna , botany , peat , actinobacteria , microorganism , microbiology and biotechnology , bacteria , biochemistry , 16s ribosomal rna , ecology , gene , genetics
Northern peatlands play a crucial role in the global carbon balance, serving as a persistent sink for atmospheric CO 2 and a global carbon store. Their most extensive type, Sphagnum ‐dominated acidic peatlands, is inhabited by microorganisms with poorly understood degradation capabilities. Here, we applied a combination of barcoded pyrosequencing of SSU rRNA genes and Illumina RNA ‐Seq of total RNA (metatranscriptomics) to identify microbial populations and enzymes involved in degrading the major components of Sphagnum ‐derived litter and exoskeletons of peat‐inhabiting arthropods: cellulose, xylan, pectin and chitin. Biopolymer addition to peat induced a threefold to fivefold increase in bacterial cell numbers. Functional community profiles of assembled mRNA differed between experimental treatments. In particular, pectin and xylan triggered increased transcript abundance of genes involved in energy metabolism and central carbon metabolism, such as glycolysis and TCA cycle. Concurrently, the substrate‐induced activity of bacteria on these two biopolymers stimulated grazing of peat‐inhabiting protozoa. Alveolata (ciliates) was the most responsive protozoa group as confirmed by analysis of both SSU rRNA genes and SSU rRNA . A stimulation of alphaproteobacterial methanotrophs on pectin was consistently shown by rRNA and mRNA data. Most likely, their significant enrichment was due to the utilization of methanol released during the degradation of pectin. Analysis of SSU rRNA and total mRNA revealed a specific response of Acidobacteria and Actinobacteria to chitin and pectin , respectively. Relatives of Telmatobacter bradus were most responsive among the Acidobacteria , while the actinobacterial response was primarily affiliated with Frankiales and Propionibacteriales . The expression of a wide repertoire of carbohydrate‐active enzymes ( CAZ ymes) corresponded well to the detection of a highly diverse peat‐inhabiting microbial community, which is dominated by yet uncultivated bacteria.