DSpace Collection:

Sandaracinobacter neustonicus sp. nov., isolated from the sea surface microlayer in the Southwestern Pacific Ocean, and emended description of the genus Sandaracinobacter

2020-08-01T00:00:00Z

Title: Sandaracinobacter neustonicus sp. nov., isolated from the sea surface microlayer in the Southwestern Pacific Ocean, and emended description of the genus Sandaracinobacter Authors: Lee, Inae; Jang, Gwang Il; Cho, Yirang; Yoon, Soo Jung; Pham, Ha My; Nguyen, Anh Vu; Lee, Yung Mi; Park, Hyun; Rhee, Tae Siek; Kim, Sae Hun; Hwang, Chung Yeon Abstract: A Gram stain negative, non-motile, facultatively anaerobic and rod-shaped bacterial strain, designated PAMC 28131(T), was isolated from a sea surface microlayer sample in the open water of the Pacific Ocean. Phylogenetic analysis of the 16S rRNA gene sequence of strain PAMC 28131(T) revealed an affiliation to the genus Sandaracinobacter with the closest species Sandaracinobacter sibiricus RB16-17(T) (sequence similarity of 98.2%). Strain PAMC 28131(T) was able to grow optimally with 0.5-1.0% NaCl and at pH 6.5-7.0 and 30 degrees C. The polar lipids were phosphatidylglycerol, phosphatidylethanolamine, two unidentified phospholipids, an unidentified aminolipid, an unidentified glycolipid and an unidentified lipid. The major cellular fatty acids (>10%) were C-18:1 omega 6c and/or C-18:1 omega 7c, (42.6%), C-17:1 omega 6c (19.3%) and C-16:1 omega 6c and/or C-16:1 omega 7c (15.8%), and the respiratory quinone was Q-10. The genomic DNA G+C content was 65.3mol%. The phylogenetic, phenotypic and chemotaxonomic data showed that strain PAMC 28131(T) could be clearly distinguished from S. sibiricus RB16-17(T). Thus, strain PAMC 28131(T) should be classified as representing a novel species in the genus Sandaracinobacter, for which the name Sandaracinobacter neustonicus sp. nov. is proposed. The type strain is PAMC 28131(T) (=KCCM 43127(T) =JCM 30734(T)).

Metagenomic analysis of surface microlayers in the Northwestern Pacific Ocean and the Bering Sea

2017-01-01T00:00:00Z

Title: Metagenomic analysis of surface microlayers in the Northwestern Pacific Ocean and the Bering Sea Authors: Hwang, Chung Yeon; Kang, Sung-Ho; Rhee, Tae Siek; Jang, Gwangil Abstract: Surface microlayer (SML) is generally defined as a thin layer in top few millimeters of surface water in aquatic environments. The ocean SML is covering >70% of the Earth's surface and is important to understand the ocean-atmosphere interactions, such as exchange of green-house gases, production of aerosols and feasibility for remote sensing of physical parameters in oceanography. Previous studies on SML have shown a striking difference in physical, chemical and biological properties between SML and underlying water (UW; a depth of a few ten centimeters to a few meters below SML) in marine environments. SML is also interesting in a microbiological aspect because SML is exposed to strong solar (and UV) irradiation driving selective microbial colonizations and is a source of marine bioaerosols potentially impacting on cloud development, atmospheric chemistry and microbial biogeography. To investigate community structures and potential functions of SML microorganisms, two sets of SML and UW samples were collected from Northwestern Pacific Ocean and the Bering Sea and subjected to metagenomics analysis using shotgun DNA sequences. In the presentation, some results will be shown and discussed in a respect of microbial selection and adaptation to such a harsh SML environment.

Contrasting distributions of dissolved gaseous mercury concentration and evasion in the North Pacific Subarctic Gyre and the Subarctic Front

2016-01-01T00:00:00Z

Title: Contrasting distributions of dissolved gaseous mercury concentration and evasion in the North Pacific Subarctic Gyre and the Subarctic Front Authors: Kim, Hyunji; Han, Seunghee; Yang, Jisook; Hwang, Chung Yeon; Hahm, Doshick; Rhee, Tae Siek Abstract: Dissolved gaseous mercury (DGM) and methylmercury (MeHg) produced in the oceanic water column is an important inorganic Hg(II) transformation process involving atmosphere-water interactions and food web bioaccumulations, respectively. Although oxygen utilization has been reported to contribute significantly to MeHg variation, its contribution to the DGM variation is largely unknown. Here, we investigated DGM and MeHg distributions in relation to oxygen utilization in the Western Subarctic Gyre (WSG). We observed subsurface peaks of DGM (203？878 fM) and MeHg (274？750 fM) at a water depth of 200 or 300 m with a minimum oxygen concentration of 60？86 μmol kg？1. The apparent oxygen utilization of WSG water was positively and linearly associated with DGM (r2=0.83) and MeHg (r2=0.93), which might be a consequence of particulate organic carbon remineralization over a period of years (< 25 yrs). The DGM concentration was typically lower in the Subarctic Front than the other sites in relation to the dissolved oxygen and nutrient concentrations, while MeHg concentration was not. It might be attributable to increases in kox/kred, associated with isopycnal mixing between Kuroshio and Oyashio waters. The DGM and MeHg input from suboxic water should be placed in context with in situ production at the surface to better understand the biogeochemical cycles of Hg in ocean water.

Oceanic source strength of carbon monoxide on the basis of basin-wide observations in the Atlantic

2016-01-01T00:00:00Z

Title: Oceanic source strength of carbon monoxide on the basis of basin-wide observations in the Atlantic Authors: Park, Kihong; Rhee, Tae Siek Abstract: We measured the carbon monoxide (CO) concentrations in the marine boundary layer and the surface waters of the Atlantic Ocean from 50°N to 50°S during the UK Atlantic Meridional Transect expedition (AMT-7) in October 1998, covering the open ocean and coastal regions. Throughout the cruise track, atmospheric CO concentrations continually decreased southwards in the northern hemisphere with sporadic low and high concentrations encountered. South to the intertropical convergence zone (ITCZ) atmospheric CO was enhanced by ~10 ppb compared to north to ITCZ due likely to biomass burning emissions prevailed in the tropical continents. The remainder of the southern hemisphere reveals nearly invariable except for the vicinity of Rio de la Plata. The surface seawater was supersaturated everywhere along the track. The saturation anomaly of dissolved CO rose up to 90 with exhibiting a strong diurnal cycle. Maximal dissolved CO concentration in the diurnal cycle appeared 2 ？ 5 hours behind local maximum of solar insolation in the open ocean and the time lag further increased in the coastal region. The global ocean flux of CO to the atmosphere was estimated as 14 Tg(CO) a-1 with ranges of 4 ？ 24 Tg(CO) a-1. This is within uncertainty almost identical to what was estimated on the basis of the basin-wide observations in the Pacific and the Atlantic, but more than ~4 times lower than the values appeared in the Intergovernmental Panel on Climate Change (IPCC) reports.