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.
Männistö
Minna K
MK
Finnish Forest Research Institute, Eteläranta 55, 96300 Rovaniemi, Finland. minna.mannisto@metla.fi
Tiirola
Marja
M
Häggblom
Max M
MM
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