Changes in microbial communities along redox gradients in polygonized Arctic wet tundra soils

• Published in: Environmental Microbiology Reports
• Main Authors: Lipson, David A., Raab, Theodore K., Parker, Melanie, Kelley, Scott T., Brislawn, Colin J., Jansson, Janet
• Other Authors: National Science Foundation, Pacific Northwest National Laboratory
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2015
• Subjects: Arctic; Tundra
• Online Access: http://dx.doi.org/10.1111/1758-2229.12301; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2F1758-2229.12301; http://onlinelibrary.wiley.com/wol1/doi/10.1111/1758-2229.12301/fullpdf

Summary This study investigated how microbial community structure and diversity varied with depth and topography in ice wedge polygons of wet tundra of the A rctic C oastal P lain in northern A laska and what soil variables explain these patterns. We observed strong changes in community structure and diversity with depth, and more subtle changes between areas of high and low topography, with the largest differences apparent near the soil surface. These patterns are most strongly correlated with redox gradients (measured using the ratio of reduced F e to total F e in acid extracts as a proxy): conditions grew more reducing with depth and were most oxidized in shallow regions of polygon rims. Organic matter and pH also changed with depth and topography but were less effective predictors of the microbial community structure and relative abundance of specific taxa. Of all other measured variables, lactic acid concentration was the best, in combination with redox, for describing the microbial community. We conclude that redox conditions are the dominant force in shaping microbial communities in this landscape. Oxygen and other electron acceptors allowed for the greatest diversity of microbes: at depth the community was reduced to a simpler core of anaerobes, dominated by fermenters ( Bacteroidetes and Firmicutes ).