Temporal changes in soil bacterial diversity and humic substances degradation in subarctic tundra soil
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- Temporal changes in soil bacterial diversity and humic substances degradation in subarctic tundra soil
- Other Titles
- 아북극권 툰드라 토양 내 미생물 군집 및 부식질 분해률의 시간별 분석
- Park, Ha Ju
Lee, Yoo Kyung
Lee, Bang Yong
Sul, Woo Jun
Chae, Nam Yi
- degradation; humic substances; low temperature; microbial community; temperature rise; tundra soil
- Issue Date
- Park, Ha Ju, et al. 2015. "Temporal changes in soil bacterial diversity and humic substances degradation in subarctic tundra soil". MICROBIAL ECOLOGY, 69(3): 668-675.
- Humic substances (HS), primarily humic acids (HA) and fulvic acids (FA), are the largest constituent of soil organic matter. In microcosm systems with subarctic HS-rich tundra soil (site AK 1-75;approximately 5.6？C during the thawing period) from Council, Alaska, the HA content significantly decreased to 48% after 99 day-incubation at 5oC as part of a biologically-mediated process. Accordingly, levels of FA, a putative byproduct of HA degradation, consistently increased to 172% during an identical incubation process. Culture-independent microbial community analysis showed that during the microcosm experiments, the relative abundance of phyla Proteobacteria (bacteria) and Euryarchaeota (archaea) largely increased, indicating their involvement in HS degradation. When the indigenous bacteria in AK 1-75 were enriched in an artificial mineral medium spiked with HA, the changes in relative abundance were most conspicuous in Proteobacteria (from 60.2% to 79.0%), specifically Betaproteobacteria-related bacteria. One hundred twenty-two HA-degrading bacterial strains, primarily from the genera Paenibacillus (phylum Firmicutes) and Pseudomonas (class Gammaproteobacteria), were cultivated from AK 1-75 and nearby sites. Through culture-dependent analysis with these bacterial isolates, we observed increasing HS-degradation rates in parallel with rising temperatures in a range of 0 to 20？C, with the most notable increase occurring at 8？C compared to 6？C. Our results indicate that, although microbial-mediated HS degradation occurs at temperature as low as 5？C in tundra ecosystems, increasing soil temperature caused by global climate change could enhance HS degradation rates. Extending the thawing period could also increase degradation activity, thereby directly affecting nearby microbial communities and rhizosphere environments.
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