DSpace Collection:

Hymenobacter siberiensis sp. nov., isolated from a marine sediment of the East Siberian Sea and Hymenobacter psoromatis sp. nov., isolated from an Antarctic lichen

Sat, 01 Jan 2022 00:00:00 GMT

Title: Hymenobacter siberiensis sp. nov., isolated from a marine sediment of the East Siberian Sea and Hymenobacter psoromatis sp. nov., isolated from an Antarctic lichen Authors: 박예린; Noh, Hyun-Ju; 황청연; Shin, Seung Chul; Hong, Soon Gyu; Jin, Young Keun; Lee, Hyoungseok; Lee, Yung Mi Abstract: Gram-staining-negative, strictly aerobic, red-pink-colored, rod-shaped, and non-motile bacterial strains, PAMC 29290, PAMC 29294T and PAMC 29296 were isolated from marine surface sediments of the East Siberian Sea and PAMC 26553 and PAMC 26554T were obtained from an Antarctic lichen, Psoroma antarcticum. Phylogenetic and phylogenomic analyses revealed that strains PAMC 29290, PAMC 29294T, PAMC 29296, PAMC 26553 and PAMC 26554T belong to the genus Hymenobacter. Strains PAMC 29290, PAMC 29294T and PAMC 29296 were closely related with Hymenobacter artigasi (98.8% 16S rRNA gene similarity), Hymenobacter antarcticus (97.3%) and Hymenobacter glaciei (96.9%) and PAMC 26553 and PAMC 26554T showed high similarity with Hymenobacter ginsengisoli (97.0%), Hymenobacter rivuli (96.1%) and Hymenobacter setariae (95.9%). Genomic relatedness analyses showed that strains PAMC 29290, PAMC 29294T and PAMC 29296 are distinguished from H. artigasi with average nucleotide identity (ANI) values (93.1？93.2%) and digital DNA-DNA hybridization (dDDH) values (50.3？51.0%). PAMC 26553 and PAMC 26554T are clearly distinguished from H. ginsengisoli with ANI values (< 79.8%) and dDDH values (< 23.3%). The major fatty acids of strains PAMC 29290, PAMC 29294T and PAMC 29296 were C15:0 iso (21.0？26.0%), summed feature 3 (C16:1 ω7c and/or C16:1 ω6c; 17.4？18.2%), C15:0 anteiso (12.7？19.1%), and summed feature 4 (C17:1 iso I and/or anteiso B; 8.6？16.1%) and those of strains PAMC 26553 and PAMC 26554T were summed feature 3 (C16:1 ω7c and/or C16:1 ω6c; 20.7？22.2%), C15:0 anteiso (17.5？19.7%), and summed feature 4 (C17:1 iso I and/or anteiso B; 15.5？18.1%). The major respiratory quinone was MK-7. The genomic DNA G+C contents were 60.6？60.8%. The polar lipids of PAMC 29294T were found to consist of phosphatidylethanolamine, four unidentified aminolipids, an unidentified aminophospholipid, and five unidentified lipids and those of PAMC 26554T were phosphatidylethanolamine, three unidentified aminolipids, four unidentified aminophospholipid, and two unidentified lipids. The distinct phylogenetic position and some physiological characteristics distinguished strains PAMC 29290, PAMC 29294T, PAMC 29296, PAMC 26553 and PAMC 26554T from other species in the genus Hymenobacter. Based on the phylogenetic, biochemical, and chemotaxonomic analyses, two novel species are proposed as Hymenobacter siberiensis sp. nov. (type strain, PAMC 29294T = KCTC 82466T = JCM 34574T) and Hymenobacter psoromatis PAMC 26554T sp. nov. (type strain, PAMC 26554T = KCTC 82464T = JCM 34572T) respectively.

Climate warming-driven changes in the flux of dissolved organic matter and its effects on bacterial communities in the Arctic Ocean: A review

Sat, 01 Jan 2022 00:00:00 GMT

Title: Climate warming-driven changes in the flux of dissolved organic matter and its effects on bacterial communities in the Arctic Ocean: A review Authors: Hien Thi Nguyen; Lee, Yung Mi; Hong, Jong Kuk; Seongjin Hong; Meilian Chen; Jin Hur Abstract: The warming of the Arctic Ocean impacts the dissolved organic matter (DOM) imports into the Arctic region, which affects the local bacterial communities. This review addressed the current status of DOM inputs and their potential influences on bacteria data (e.g., population, production, and metabolic activity of bacteria), as well as the projected changes of DOMinputs and bacterial communities as a result of climate warming. Microbial communities are likely affected by the warming climate and the transport of DOM to the Arctic Ocean. Imported DOM can alter Arctic bacterial abundance, cell size, metabolism, and composition. DOM fluxes from Arctic River runoff and adjacent oceans have been enhanced, with warming increasing the contribution of many emerging DOM sources, such as phytoplankton production, melted sea ice, thawed permafrost soil, thawed subsea permafrost, melted glaciers/ice sheets, atmospheric deposition, groundwater discharge, and sediment efflux. Imported DOM contains both allochthonous and autochthonous components; a large quantity of labile DOM comes from emerging sources. As a result, the Arctic sea water DOM composition is transformed to include a wider range of various organic constituents such as carbohydrates (i.e., glucose), proteinaceous compounds (i.e., amino acid and protein-like components) and those with terrigenous origins (i.e., humic-like components). Changes to DOM imports can alter Arctic bacterial abundance, cell size,metabolism, and composition. Under current global warming projections, increased inflow of DOM and more diverse DOM composition would eventually lead to enhanced CO2 emissions and frequent emergence of replacement bacterial communities in the Arctic Ocean. Understanding the changes in DOM fluxes and responses of bacteria in the Arctic broadens our current knowledge of the Arctic Ocean’s responses to global warming.

Estimation of the gas hydrate saturation from multichannel seismic data on the western continental margin of the Chukchi Rise in the Arctic Ocean

Sat, 01 Jan 2022 00:00:00 GMT

Title: Estimation of the gas hydrate saturation from multichannel seismic data on the western continental margin of the Chukchi Rise in the Arctic Ocean Authors: Choi, Yeonjin; Kang, Seung-Goo; Jin, Young Keun; Hong, Jong Kuk; 신성렬; 김수관; 최영일 Abstract: A multichannel seismic survey was conducted to investigate the geophysical characteristics of gas hydrates along the western continental margin of the Chukchi Rise around an ARAON mound cluster, which was first recovered in 2016. In the seismic data, gas hydrate-related bottom simulating reflection was widely distributed along the western continental margin of the Chukchi Rise. High-precision seismic P- wave velocity was obtained to investigate the geophysical characteristics of the gas hydrate structures in the BSR areas. Iterative migration velocity analysis was used to construct a detailed P-wave velocity model from the acquired seismic data. The gas hydrate and free gas layers have abnormally high- and low-seismic P-wave velocities; the precise velocity model allows us to understand the detailed spatial distribution of gas hydrate and free gas structures. The effective medium theory model enables estimations of the gas hydrate saturation from constructed seismic P-wave velocity model. We propose the P-wave velocity and gas hydrate saturation models from acquired multichannel seismic data in the western continental margin of the Chukchi Rise for the first time.

Mercury and other trace elements distribution and profiling of microbial community in the surface sediments of East Siberian Sea

Sat, 01 Jan 2022 00:00:00 GMT

Title: Mercury and other trace elements distribution and profiling of microbial community in the surface sediments of East Siberian Sea Authors: Dhiraj Kumar Chaudhary; Hem Prakash Karki; Rishikesh Bajagain; Hwansuk Kim; Rhee, Tae Siek; Hong, Jong Kuk; Seunghee Han; Young-Gyun Choi; Yongseok Hong Abstract: In this study, total mercury (THg), methylmercury (MeHg), various trace elements, and microbial communities were measured in surface sediments of the East Siberian Sea (ESS). The results showed that the average values of THg and MeHg were 58.8 ± 15.21 μg/kg and 0.50 ± 0.22 μg/kg, respectively. The notable levels of trace elements present in both surface sediment and porewater were Al, Fe, and Mn. The enrichment factor and geo-accumulation index analyses found that both natural phenomena and anthropogenic activities contributed to elevated concentrations of metals in the ESS. The redox proxy metals, pH, and SO42- were the major factors influencing the THg and MeHg distributions. Microbial profiles were substantially affected by metals and other abiotic factors. Proteobacteria and Thaumarchaeota were the most abundant phyla. Overall, the findings presented here facilitate the understanding of the current status of metal contamination, its influencing factors, and metal-microbiota-interactions in ESS.