Effect of freeze-thaw cycles on bacterial communities of arctic tundra soil.
The effect of freeze-thaw (FT) cycles on Arctic tundra soil bacterial community was studied in laboratory microcosms. FT-induced changes to the bacterial community were followed over a 60-day period by terminal restriction fragment length polymorphism (T-RFLP) profiles of amplified 16S rRNA genes and reverse transcribed 16S rRNA. The main phylotypes of the active, RNA-derived bacterial community were identified using clone analysis. Non-metric multidimensional scaling ordination of the T-RFLP profiles indicated some shifts in the bacterial communities after three to five FT cycles at -2, -5, and -10 degrees C as analyzed both from the DNA and rRNA. The dominating T-RFLP peaks remained the same, however, and only slight variation was generally detected in the relative abundance of the main T-RF sizes of either DNA or rRNA. T-RFLP analysis coupled to clone analysis of reverse transcribed 16S rRNA indicated that the initial soil was dominated by members of Bacteroidetes, Acidobacteria, Alpha-, Beta-, and Gammaproteobacteria. The most notable change in the rRNA-derived bacterial community was a decrease in the relative abundance of a Betaproteobacteria-related phylotype after the FT cycles. This phylotype decreased, however, also in the control soil incubated at constant +5 degrees C suggesting that the decrease was not directly related to FT sensitivity. The results indicate that FT caused only minor changes in the bacterial community structure.
Finnish Forest Research Institute, Eteläranta 55, 96300 Rovaniemi, Finland. minna.mannisto@metla.fi
Minna K
MK
Männistö
Marja
M
Tiirola
Max M
MM
Häggblom
D001110:Arctic Regions; D001419:Bacteria / Q000145:classification / Q000235:genetics*; D003080:Cold Temperature; D004269:DNA, Bacterial / Q000235:genetics; D017753:Ecosystem; D005387:Finland; D005615:Freezing; D010802:Phylogeny; D012150:Polymorphism, Restriction Fragment Length; D011157:Population Dynamics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012988:Soil Microbiology
D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S