Microbial community structure and functional genes associated with four boreal vegetation types

Microorganisms constitute some of the most functionally diverse organisms on the planet, with metabolic capabilities ranging from nutrient cycling to xenobiotic pollutant degradation.  Many environmental variables such as vegetation type, temperature, nutrient status, and contamination have been found to influence microbial community composition.  The influence of environmental factors on microbial community structure (the abundance and identity of different organisms) and function (metabolic capabilities potentially active in the community and ecosystem processes provided by the community), is important to understanding ecosystem function and is a focal question of ecological research.  We used bar-coded 454-pyrosequencing of bacterial 16S rRNA genes and GeoChip functional gene microarray analysis to screen the microbial structural and functional potential of soils associated with four vegetation types dominated by either Picea glauca (white spruce), Picea mariana (black spruce), Populus tremuloides (quaking aspen), or Betula neoalaskana (Alaskan paper birch), located within the Bonanza Creek Long Term Ecological Research Site (BNZ LTER) in interior Alaska.  Results indicate that microbes with the genetic functional potential to degrade chlorinated solvents, hydrocarbons, herbicides, pesticides, and other aromatic compounds are present in varying amounts in the root zone of each tree species.  Results also indicated that microbial communities and functional metagenomes vary in composition in accordance with the dominant tree species present.  This study provides insight to the environmental drivers of microbial communities.