The role of laccase in stabilization of soil organic matter by iron in various plant-dominated peatlands: degradation or sequestration?
2019
Zhao, Yunpeng | Xiang, Wu | Ma, Ming | Zhang, Xiuzhi | Bao, Zhengyu | Xie, Shuyun | Yan, Sen
AIMS: The association of organic matter with iron (Fe-OM associations) is recognized as an important stabilization mechanism for soil organic matter. Our objective was to assess the factors regulating stabilization of soil organic matter by iron in various plant-dominated peatlands, and the role of laccase in the formation of Fe-OM associations. METHODS: We investigated Fe-bound OC content and related physicochemical and biochemical parameters in four plots with different successional vegetation, and a set of simulations was conducted to investigate the association of Fe and peat-derived dissolved organic carbon catalysed by laccase. RESULTS: Our results indicate Fe-bound OC content varies regularly with the succession gradients, and a significant positive relationship between laccase activities and Fe-bound OC content was found (R = 0.77, P < 0.05). Although laccase degradation of recalcitrant polyphenolics is related with the CO₂ release from peat soils (R = 0.697; P < 0.05), the simulation results confirmed laccase can significantly promote the formation of Fe-OM association. CONCLUSIONS: We propose that laccase plays a unique multifunctional role in the peatland carbon cycle. That is, while laccase degrades refractory organic matter such as lignin, it may enhance carbon sequestration by promoting the formation of Fe-OM association, which is particularly effective in acidic peat environments containing abundant iron and laccase-producing fungi.
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