I measured 13C enrichment of phospholipid fatty acids (PLFAs), respired CO2 and biomass as indicators of activity. Characteristic PLFAs were used as biomarkers for taxonomic groups such as fungi, Gram(+) and Gram(-) bacteria. BrdU is a thymidine analog that microbes incorporate into newly synthesized DNA. Using immunocapture, I was able to isolate the DNA of actively growing organisms. I analyzed the active bacterial communities using terminal restriction length polymorphisms. Based on BrdU analyses, active bacteria in shrub tundra differ between summer and winter whereas active bacteria in tussock tundra are relatively stable between seasons. Not all taxonomic groups were equally active in all soils. Generally, fungi were more active in winter and bacteria in summer, though in tussock tundra both fungi and Gram(-) bacteria were consistently active throughout the year. Microbes used substrates differently depending on season.Also, whereas permafrost microbes must perform some maintenance or growth in order to repair macromolecular ... and from laboratory studies of CO2 production at sub-zero temperatures (Schimel and Mikan, 2005; Panikov et al., 2006).
|Title||:||Winter Microbial Carbon Metabolism and Community Composition in Alaskan Tundra Soil|
|Author||:||Shawna Katherine McMahon|
|Publisher||:||ProQuest - 2008|