Title Soil water content as a critical factor for stable bacterial community structure and degradative activity in maritime Antarctic soil
Author Dockyu Kim1†*, Namyi Chae2, Mincheol Kim1, Sungjin Nam1, Eungbin Kim3, and Hyoungseok Lee1
Address 1Division of Life Sciences, Korea Polar Research Institute, Incheon 21990, Republic of Korea, 2Institutes of Life Sciences and Natural Resources, Korea University, Seoul 02841, Republic of Korea, 3Department of Systems Biology, Yonsei University, Seoul 03722, Republic of Korea
Bibliography Journal of Microbiology, 58(12),1010–1017, 2020,
DOI 10.1007/s12275-020-0490-9
Key Words Antarctic tundra soil, bacterial composition, degradative activity, humic substances, microcosm
Abstract Recent increases in air temperature across the Antarctic Peninsula may prolong the thawing period and directly affect the soil temperature (Ts) and volumetric soil water content (SWC) in maritime tundra. Under an 8°C soil warming scenario, two customized microcosm systems with maritime Antarctic soils were incubated to investigate the differential influence of SWC on the bacterial community and degradation activity of humic substances (HS), the largest constituent of soil organic carbon and a key component of the terrestrial ecosystem. When the microcosm soil (KS1-4Feb) was incubated for 90 days (T = 90) at a constant SWC of ~32%, the initial HS content (167.0 mg/g of dried soil) decreased to 156.0 mg (approximately 6.6% loss, p < 0.05). However, when another microcosm soil (KS1-4Apr) was incubated with SWCs that gradually decreased from 37% to 9% for T = 90, HS degradation was undetected. The low HS degradative activity persisted, even after the SWC was restored to 30% with water supply for an additional T = 30. Overall bacterial community structure remained relatively stable at a constant SWC setting (KS1-4Feb). In contrast, we saw marked shifts in the bacterial community structure with the changing SWC regimen (KS1-4Apr), suggesting that the soil bacterial communities are vulnerable to drying and re-wetting conditions. These microcosm experiments provide new information regarding the effects of constant SWC and higher Ts on bacterial communities for HS degradation in maritime Antarctic tundra soil.