DSpace Collection:

Passive warming effect on soil microbial community and humic substance degradation in maritime Antarctic region

2018-02-01T00:00:00Z

Title: Passive warming effect on soil microbial community and humic substance degradation in maritime Antarctic region Authors: Kim, Dockyu; Park, Ha Ju; Kim, Jung Ho; Youn, Ui Joung; Yang, Yung Hun; Casanova-Katny, Angelica; Munoz Vargas, Cristina; Venegas, Erick Zagal; Park, Hyun; Hong, Soon Gyu Abstract: Although the maritime Antarctic has undergone rapid warming, the effects on indigenous soil-inhabiting microorganisms are not well known. Passive warming experiments using open-top chamber (OTC) have been performed on the Fildes Peninsula in the maritime Antarctic since 2008. When the soil temperature was measured at a depth of 2？5 cm during the 2013？2015 summer seasons, the mean temperature inside OTC (OTC-In) increased by approximately 0.8ºC compared with outside OTC (OTC-Out), while soil chemical and physical characteristics were not changed. Soils (2015 summer) from OTC-In and OTC-Out were subjected to analysis for change in microbial community and degradation rate of humic substances (HS, the largest pool of recalcitrant organic carbon in soil). Archaeal and bacterial communities in OTC-In were minimally affected by warming compared with those in OTC-Out, with archaeal methanogenic Thermoplasmata slightly increased in abundance. The abundance of heterotrophic fungi Ascomycota was significantly altered in OTC-In. Total bacterial and fungal biomass in OTC-In increased by 20% compared to OTC-Out, indicating that this may be due to increased microbial degradation activity for soil organic matter (SOM) including HS, which would result in the release of more low-molecular-weight growth substrates from SOM. Despite the effects of warming on the microbial community over the 8-years-experiments warming did not induce any detectable change in content or structure of polymeric HS. These results suggest that increased temperature may have significant and direct effects on soil microbial communities inhabiting maritime Antarctic.

Transcriptome analysis of Pseudomonas sp. from subarctic tundra soil: pathway description and gene discovery for humic acids degradation

2017-12-01T00:00:00Z

Title: Transcriptome analysis of Pseudomonas sp. from subarctic tundra soil: pathway description and gene discovery for humic acids degradation Authors: Kim, Dockyu; Park, Hyun; Sul, Woo Jun; Park, Ha Ju Abstract: Although humic acids (HA) are involved in many biological processes in soils and thus their ecological importance has received much attention, the degradative pathways and corresponding catalytic genes underlying the HA degradation by bacteria remain unclear. To unveil those uncertainties, we analyzed transcriptomes extracted from Pseudomonas sp. PAMC 26793 cells time-dependently induced in the presence of HA in a lab flask. Out of 6,288 genes, 299 (microarray) and 585 (RNA-seq) were up-regulated by >2.0-fold in HA-induced cells, compared with controls. A significant portion (9.7% in microarray and 24.1% in RNA-seq) of these genes are predicted to function in the transport and metabolism of small molecule compounds, which could result from microbial HA degradation. To further identify lignin (a surrogate for HA) degradative genes, 6,288 protein sequences were analyzed against CAZy database and a self-curated list of putative lignin degradative genes. Out of 19 genes predicted to function in lignin degradation, several genes encoding laccase, dye-decolorizing peroxidase, vanillate O-demethylase oxygenase and reductase, and biphenyl 2,3-dioxygenase were up-regulated >2.0-fold in RNA-seq. This induction was further confirmed by qRT-PCR, validating the likely involvement of these genes in the degradation of HA.

Antarctic organisms: Cold-adaptation mechanism and it's applicarion

2017-07-28T00:00:00Z

Title: Antarctic organisms: Cold-adaptation mechanism and it's applicarion Authors: Park, Hyun

Computational approach to understand structural of cold-adapted proteins

2017-01-31T00:00:00Z

Title: Computational approach to understand structural of cold-adapted proteins Authors: Park, HaJeung