Ice nucleating particles (INPs) are vital for ice initiation in, and precipitation from, mixed-phase clouds. A source of INPs from oceans within sea spray aerosol (SSA) emissions has been suggested in previous studies but remained unconfirmed. Here, we show that INPs are emitted using real wave breaking in a laboratory flume to produce SSA. The number concentrations of INPs from laboratory-generated SSA, when normalized to typical total aerosol number concentrations in the marine boundary layer, agree well with measurements from diverse regions over the oceans. Data in the present study are also in accord with previously published INP measurements made over remote ocean regions. INP number concentrations active within liquid water droplets increase exponentially in number with a decrease in temperature below 0 °C, averaging an order of magnitude increase per 5 °C interval. The plausibility of a strong increase in SSA INP emissions in association with phytoplankton blooms is also shown in laboratory simulations. Nevertheless, INP number concentrations, or active site densities approximated using “dry” geometric SSA surface areas, are a few orders of magnitude lower than corresponding concentrations or site densities in the surface boundary layer over continental regions. These findings have important implications for cloud radiative forcing and precipitation within low-level and midlevel marine clouds unaffected by continental INP sources, such as may occur over the Southern Ocean.

The subarctic region is highly responsive and vulnerable to climate change. Understanding the structure of subarctic soil microbial communities is ess

Modern studies on marine airborne prokaryotes over open seas have been rare. Here, to understand their distribution and composition, aerosol as well

A slightly curved, rod-shaped marine bacterium, designated strain CL-S1^T, was isolated from near Dokdo, an island in the East Sea, Korea. Cells were Gram-negative and grew well under either aerobic or microaerobic conditions. Analyses of the 16S rRNA and gyrA gene sequences of strain CL-S1^T revealed an affiliation with the genus Arcobacter within the class Epsilonproteobacteria. Phylogenetic analyses based on 16S rRNA and gyrA gene sequences showed that strain CL-S1^T formed a robust clade with Arcobacter halophilus LA31B^T, with sequence similarities of 96.1 and 88.2 %, respectively. DNA–DNA relatedness between strain CL-S1^T and A. halophilus DSM 18005^T was 44 %, indicating that they represent genomically distinct species. Strain CL-S1^T grew optimally at 30–37 °C, at pH 7 and in the presence of 3–5 % NaCl. The dominant cellular fatty acids were iso-C_15 : 0 2-OH and/or C_16 : 1 ω7c (28.4 %), C_16 : 0 (26.2 %) and C_18 : 1 ω7c (22.3 %). The DNA G+C content of strain CL-S1^T was 28 mol%. Strain CL-S1^T differed phenotypically from A. halophilus LA31B^T based on its ability to grow aerobically at 10 °C and inability to grow under anaerobic conditions. Based on the data presented, strain CL-S1^T is considered to represent a novel species of the genus Arcobacter, for which the name Arcobacter marinus sp. nov. is proposed. The type strain is CL-S1^T (=KCCM 90072^T =JCM 15502^T).

A Gram-negative, pink-coloured, rod-shaped, non-flagellated bacterium, designated CL-GP80^T, was isolated from a hypertrophic pond located within the campus of Seoul National University, Korea. Analysis of its 16S rRNA gene sequence revealed that strain CL-GP80^T belongs to the family Sphingobacteriaceae and is closely related to Pedobacter heparinus ATCC 13125^T (95.8 % sequence similarity) and to other members of the genus Pedobacter (90.8–95.3 % similarity). Temperature and pH ranges for growth were 5–33 °C and pH 6–8, respectively. The DNA G+C content was 41.3 mol%. The major fatty acids were iso-C_15 : 0 (37.0 %), iso-C_15 : 0 2-OH and/or C_16 : 1 ω7c (24.5 %), and iso-C_17 : 0 3-OH (11.3 %). Phenotypic, chemotaxonomic and phylogenetic analyses indicated that strain CL-GP80^T could be assigned to the genus Pedobacter, but distinguished from recognized species of the genus. Strain CL-GP80^T (=KCCM 42272^T=JCM 13399^T) is therefore proposed as the type strain of a novel species, for which the name Pedobacter roseus sp. nov. is proposed.

The increasing temperature in Arctic tundra deepens the active layer, which is the upper layer of permafrost soil that experiences repeated thawing and freezing. The increasing of soil temperature and the deepening of active layer seem to affect soil microbial communities. Therefore, information on soil microbial communities at various soil depths is essential to understand their potential responses to climate change in the active layer soil. We investigated the community structure of soil bacteria in the active layer from moist acidic tundra in Council, Alaska. We also interpreted their relationship with some relevant soil physicochemical characteristics along soil depth with a fine scale (5 cm depth interval). The bacterial community structure was found to change along soil depth. The relative abundances of Acidobacteria, Gammaproteobacteria, Planctomycetes, and candidate phylum WPS-2 rapidly decreased with soil depth, while those of Bacteroidetes, Chloroflexi, Gemmatimonadetes, and candidate AD3 rapidly increased. A structural shift was also found in the soil bacterial communities around 20 cm depth, where two organic (upper Oi and lower Oa) horizons are subdivided. The quality and the decomposition degree of organic matter might have influenced the bacterial community structure. Besides the organic matter quality, the vertical distribution of bacterial communities was also found to be related to soil pH and total phosphorus content. This study showed the vertical change of bacterial community in the active layer with a fine scale resolution and the possible influence of the quality of soil organic matter on shaping bacterial community structure.