First Satellite Tagging of the Northern Fur Seals (Callorhinus ursinus) on the Tyuleniy Island, the Sea of Okhotsk.

In October 2018, three Northern fur seals (two adult females and one juvenile male) were deployed with satellite tags on the Tyuleniy Island in the Sea of Okhotsk. The operational time of the tags ranged from 33 to 203 days. The adult females started their winter migration in the first half of November; the initial stage of their winter migration occurred in the Japan/East Sea, which they entered through the La Perouse Strait. The juvenile male left the rookery in mid-October, crossed the Sea of Okhotsk in a north-western direction and returned to the south. The male had reached the coastal areas of Hokkaido Island, Japan by the end of November. From the Sea of Okhotsk, the male entered the Pacific Ocean through the Yekaterina Strait and subsequently entered the Japan/East Sea via the Tsugaru Strait. The winter foraging of the male occurred within the north-eastern part of the Japan/East Sea just off the Tsugaru Strait. After 3 months, the male returned to the Pacific and remained off the Sanriku Coast (Honshu Island).

Population Structure of Finless Porpoise (Neophocaena phocaenoides) Discovered off Coastal Waters, Republic of Korea.

The finless porpoise (Neophocaena phocaenoides Cuvier, 1829) is distributed in the coastal waters of Asia, throughout Indonesia to the east, and as far north as the Taiwan Strait. The finless porpoise has been declared critically endangered by the WWF (World Wide Fund for Nature), and in 2017 was rated vulnerable on the IUCN Red Threatened Species List. Since this species is distributed near the coast and has many interactions with humans, effective conservation of the species requires further studies into their genetic diversity and population. In this study, 45 samples were obtained from bycatch or stranded individuals in the East, South, and West Seas, where Korean porpoises were mainly distributed from 2017-2021. We compared 473 bp mtDNA sequences from the control region. Pairwise fixation indices (FST) revealed that the two populations differed significantly (FST = 0.4557, p = 0.000). In contrast to high levels of genetic differentiation, gene flow was identified as medium levels (Nm of 0.04-0.71). Our data suggest that finless porpoises may have undergone a historic differentiation event, and that finless porpoises in the three regions could be divided into two populations: West and East/South.

Pathological and Genomic Findings of Erysipelothrix rhusiopathiae Isolated From a Free-Ranging Rough-Toothed Dolphin Steno bredanensis (Cetacea: Delphinidae) Stranded in Korea.

Erysipelas, caused by Erysipelothrix rhusiopathiae, is considered one of the most serious infectious diseases of captive and free-ranging cetaceans worldwide, as these animals are known to be highly susceptible to the bacterial infections. The potential diversity between E. rhusiopathiae isolates from captive cetaceans has been previously described; however, the microbiological features of the free-ranging cetacean isolates remain unclear. Here, we describe a case of bacteremia in a rough-toothed dolphin (Steno bredanensis) caused by E. rhusiopathiae. Additionally, we present the first genomic features of the bacteria from free-ranging cetacean individuals. Histopathological and microbial examinations revealed that E. rhusiopathiae caused bacteremia and systemic infection in the dolphin. The genome of the isolated E. rhusiopathiae strain KC-Sb-R1, which was classified as Clade 1 possessing SpaB gene, was clearly differentiated from the other swine-isolated E. rhusiopathiae, and the comparison of its serovar-defining chromosomal region revealed that our isolate was greatly similar to those of other previously reported serovar 2/15 isolates, including the captive-dolphin isolate. Moreover, most of the potential virulence factors in the strain KC-Sb-R1 were similar to those in the strain Fujisawa. Further, a potential cytotoxicity of the isolate was confirmed, suggesting that marine mammal-isolated E. rhusiopathiae could possess strong pathogenic potential in other animals, including humans. These results would further increase our understanding on the risk factors for controlling zoonotic pathogens of emerging infectious diseases in captive or free-ranging cetaceans, and also provide important insight into the diversity of E. rhusiopathiae in animals.

Chromosomal assembly of the Antarctic toothfish ( Dissostichus mawsoni) genome using third-generation DNA sequencing and Hi-C technology.

The Antarctic toothfish, Dissostichus mawsoni, belongs to the Nototheniidae family and is distributed in sub-zero temperatures below S60° latitude in the Southern Ocean. Therefore, it is an attractive model species to study the stenothermal cold-adapted character state. In this study, we successfully generated highly contiguous genome sequences of D. mawsoni, which contained 1 062 scaffolds with a N50 length of 36.98 Mb and longest scaffold length of 46.82 Mb. Repetitive elements accounted for 40.87% of the genome. We also inferred 32 914 protein-coding genes using in silico gene prediction and transcriptome sequencing and detected splicing variants using Isoform-Sequencing (Iso-Seq), which will be invaluable resource for further exploration of the adaptation mechanisms of Antarctic toothfish. This new high-quality reference genome of D. mawsoni provides a fundamental resource for a deeper understanding of cold adaptation and conservation of species.

Assessment of the Dynamics of Microbial Community Associated with Tetraselmis suecica Culture under Different LED Lights Using Next-Generation Sequencing.

Tetraselmis is a green algal genus, some of whose species are important in aquaculture as well as biotechnology. In algal culture, fluorescent lamps, traditional light source for culturing algae, are now being replaced by a cost-effective light-emitting diodes (LEDs). In this study, we investigated the effect of LED light of different wavelengths (white, red, yellow, and blue) on the growth of Tetraselmis suecica and its associated microbial community structures using the next-generation sequencing (NGS). The fastest growth rate of T. suecica was shown in the red light, whereas the slowest was in yellow. The highest OTUs (3426) were identified on day 0, whereas the lowest ones (308) were found on day 15 under red light. The top 100 OTUs associated with day 0 and day 5 cultures of T. suecica under the red and yellow LED were compared. Only 26 OTUs were commonly identified among four samples. The highest numbers of unique OTUs were identified at day 0, indicating the high degree of initial microbial diversity of the T. suecica inoculum. The red light-unique OTUs occupied 34.98%, whereas the yellow-specific OTUs accounted for only 2.2%. This result suggested a higher degree of interaction in T. suecica culture under the red light, where stronger photosynthesis occurs. Apparently, the microbial community associated with T. suecica related to the oxygen produced by algal photosynthesis. This result may expand our knowledge about the algaebacteria consortia, which would be useful for various biotechnological applications including wastewater treatment, bioremediation, and sustainable aquaculture.

Erratum to: Bacillus piscis sp. nov., a novel bacterium isolated from the muscle of the antarctic fish Dissostichus mawsoni.

In the article by Lee et al. published in Journal of Microbiology 2016; 54, 809-813, The KCTC accession number KCTC 18866T in abstract and foot note should be corrected to KCTC 33839T.The sentence in abstract should have read: Based on the phylogenetic, phenotypic, and chemotaxonomic data, strain 16MFT21T (=KCTC 33839T =JCM 31664T). The species description in foot note should have read: The NCBI GenBank/EMBL/DDBJ accession number for the 16S rRNA gene sequence of strain 16MFT21T (=KCTC 33839T =JCM 31664T) is KX753358.We apologize for any inconvenience that this may have caused.

The full-length mitochondrial genome of the Fernholm's hagfish, Myxine fernholmi (Myxini; Myxiniformes; Myxinidae).

The full-length mitochondrial genome of the Fernholm's hagfish, Myxine fernholmi (Myxini; Myxiniformes; Myxinidae) was analyzed by the primer walking method. Its mitogenome was 18,862 bp in total length and was composed of 13 protein-coding genes, two ribosomal RNA genes, and 22 transfer RNA genes. The gene content and order were congruent with those of typical vertebrates. In the phylogenetic tree, M. fernholmi showed the closest relationship to M. glutinosa in the same genus and subfamily and well separated from the other hagfish in the subfamily Eptatretinae.

Characterization of the complete mitochondrial genome of Chionobathyscus dewitti (Perciformes, Channichthyidae).

The complete mitochondrial genome sequence of the Icefish, Chionobathyscus dewitti was determined by the Next Generation Sequencing (NGS) analysis. The complete mitogenome was 17,452 bp in length, which encoded the canonical 13 protein-coding genes, 22 tRNAs, two rRNAs, and two non-coding regions. As shown in the other notothenids, translocation of ND6 and an additional non-coding region were identified, which is different from the typical vertebrate mitochondrial genomes. The C. dewitti was clustered distinctly from the those in the Chinodraco and Chaenocephalus, which supported the idea that this species should be classified in the different genus, Chionobathyscus in the family Channichthyidae.

Total and Methyl Mercury Concentrations in Antarctic Toothfish (Dissostichus mawsoni): Health Risk Assessment.

The concentrations of total mercury (THg) in different organs of the Antarctic toothfish (Dissostichus mawsoni) collected from CCAMLR research blocks in Subarea 88.3 and Division 58.4.1 off the coast of Antarctica were determined. The results revealed THg concentrations of 0.165 ± 0.095 mg/kg (0.023-0.454 mg/kg, wet weight) in the Antarctic toothfish. In muscle, methyl mercury (MeHg) accounted for approximately 40% of the THg. In a comparison analysis, muscle and liver tended to bioaccumulate the highest levels of THg, and both THg and MeHg contents showed correlations with fish length and weight. Compared with international guidelines, fish contained 2.5-6.4% and 4.0-10.3% of the provisional tolerable weekly intake for THg recommended by the Joint FAO/WHO Expert Committee on Food Additives and the tolerable weekly intake for MeHg proposed by the European Food Safety Authority, respectively. These results suggest that consumption of the Antarctic toothfish presents no health risk to humans.

Bizionia berychis sp. nov., isolated from intestinal tract of a splendid alfonsino (Beryx splendens).

A Gram-stain-negative, non-motile, aerobic and rod-shaped bacterial strain, designated RA3-3-1T, was isolated from splendid alfonsino (Beryxsplendens) collected from the North Pacific Ocean. Strain RA3-3-1T grew optimally at 25 °C, at pH 7.0-8.0 and in the presence of 1.0-3.0 % (w/v) NaCl. The neighbour-joining phylogenetic tree based on 16S rRNA gene sequences revealed that strain RA3-3-1T belonged to the genus Bizionia, clustering with the type strain of Bizionia fulviae. Strain RA3-3-1T exhibited 16S rRNA gene sequence similarities of 98.7, 97.6 and 97.3 % to the type strains of B. fulviae, Bizionia paragorgiae and Bizionia saleffrena, respectively, and of 95.5-96.4 % to the type strains of the other Bizionia species. Strain RA3-3-1T contained MK-6 as the predominant menaquinone and anteiso-C15 : 0, iso-C16 : 0 3-OH, summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), iso-C17 : 0 3-OH, iso-C15 : 0 and C17 : 0 2-OH as the major fatty acids. The major polar lipids detected in strain RA3-3-1T were phosphatidylethanolamine, one unidentified lipid and one unidentified aminolipid. The DNA G+C content of strain RA3-3-1T was 34.1 mol% and its DNA-DNA relatedness values with the type strains of B. fulviae, B. paragorgiae and B. saleffrena were 12-29 %. Differential phenotypic properties, together with its phylogenetic and genetic distinctiveness, revealed that strain RA3-3-1T is separate from recognized species of the genus Bizionia. On the basis of the data presented, strain RA3-3-1T is considered to represent a novel species of the genus Bizionia, for which the name Bizionia berychis sp. nov. is proposed. The type strain is RA3-3-1T (=KCTC 62140T=NBRC 113024T).

Evidence of shallow mitochondrial divergence in the slender armorhead, Pentaceros wheeleri (Pisces, Pentacerotidae) from the Emperor Seamount Chain.

Competitive overexploitation of the slender armorhead, Pentaceros wheeleri, a deep-sea fish inhabiting the Emperor Seamount Chain caused a serious population decline. Therefore, it is urgently necessary to clarify its genetic diversity and connectivity among populations of P. wheeleri for appropriate stock management. For this, we compared 677 base pairs (bp) of mitochondrial (mt) DNA control region (CR) sequences of 80 individuals from three seamounts (the Milwaukee, Kinmei, and Koko Seamounts) in the southern part of the Emperor Seamount Chain. Contrary to our expectation, the three seamount populations showed high genetic diversity, not yet reflecting effects from the recent population decline or due to mixed two clades. Analysis of molecular variance indicated no significant genetic differentiation between seamount populations, however, the neighbour-joining tree and minimum spanning network showed significant separation into two clades (K2P distance= 1.2-3.2%, ϕst = 0.5739, p < .05) regardless of seamount. The divergence time between the two clades was estimated to be 0.3-0.8 Mya, during the period of Pleistocene glacial cycles, suggesting that associated environmental changes and the unique life history traits of Pentaceros spp. might have resulted in the initiation of divergence between these clades.

Larkinella roseus sp. nov., a species of the family Cytophagaceae isolated from beach soil.

The taxonomic position of bacterial strain, designated 15J16-1T3AT, recovered from a soil sample was established using a polyphasic approach. Phylogenic analysis based on the 16S rRNA gene sequence showed that strain 15J16-1T3AT belonged to the family Cytophagaceae, phylum Bacteroidetes, and was most closely related to 'Larkinella harenae' 15J9-9 (95.9% similarity), Larkinella ripae 15J11-11T (95.6%), Larkinella bovis M2TB15T (94.7%), Larkinella arboricola Z0532T (93.9%), and Larkinella insperata LMG 22510T (93.5%). Cells were rod-shaped, Gram-stain-negative, aerobic, and nonmotile. The isolate grew on NA, R2A, TSA, but not on LB agar. The strain was able to grow at temperature range from 10°C to 30°C with an optimum at 25°C and pH 6-8. Menaquinone MK-7 was the predominant respiratory quinone. The major cellular fatty acids comprised C16:1ω5c (48.6%) and C15:0 iso (24.1%). Phosphatidylethanolamine, phosphatidylserine, and an unidentified lipid were the major polar lipids. The G + C content of the genomic DNA was 49.5 mol%. Strain 15J16-1T3AT could be distinguished from its closest phylogenetic neighbors based on its phenotypic, genotypic, and chemotaxonomic features. Therefore, the isolate is considered to represent a novel species in the genus Larkinella, for which the name Larkinella roseus sp. nov. is proposed. The type strain is 15J16-1T3AT (= KCTC 52004T = JCM 31991T).

Characterization of the complete mitochondrial genome of Melibe japonica (Eliot, 1913) collected from Korean water.

Melibe japonica is the rarely identified nudibranch species in Korean and Japanese waters. Total mitochondrial genome of M. japonica collected from the coastal water of Busan, Korea, was determined by the bioinformatic assembly of the contigs generated by Illumina Miseq platform. The circular complete mitochondrial genome of M. japonica was 13, 216 bp in length, which contains 13 proteins, 2 ribosomal RNAs, and 22 tRNAs. Mitochondrial gene order of M. japonica is considerably different from the mitochondrial genome of Melibe leonina in which 6 genes (ND1, COX2, CYTB, ND4L, ND5, and ND6) were differently located. Phylogenetic analysis with COI regions showed that M. japonica is most closely related to Melibe viridis. However, not all Melibe species formed a single clade based on the phylogenetic analysis by COI region and more mitochondrial genomes in this genus should be further studied to have a better knowledge of the evolutional relationship of the nudibranchs.

Deinococcus rubellus sp. nov., bacteria isolated from the muscle of antarctic fish.

Two new bacterial strains designated as Ant6T and Ant18 were isolated from the muscle of a fish which had been caught in the Antarctic Ocean. Both strains are Gram-stain-positive, catalase positive, oxidase negative, aerobic, and coccoid bacteria. Phylogenetic analysis based on the 16S rRNA gene sequences of strains Ant6T and Ant18 revealed that the strains Ant6T and Ant18 belong to the genus Deinococcus in the family Deinococcaceae in the class Deinococci. The highest degrees of sequence similarities of strains Ant6T and Ant18 were found with Deinococcus alpinitundrae LMG 24283T by 96.4% and 96.8%, respectively. Strain Ant6T exhibited a high level of DNA- DNA hybridization values with strain Ant18 (82 ± 0.6%). Chemotaxonomic data revealed that the predominant fatty acids were C17: 0 cyclo, 16:0, and feature 3 (C16:1 ω6c/ω7c) for both strains. A complex polar lipid profile consisted of major amounts of unknown phosphoglycolipids (PGL) and unknown aminophospholipid (APL). Based on the phylogenetic, phenotypic, and chemotaxonomic data, strains Ant6T (=KEMB 9004-169T =JCM 31434T) and Ant18 (=KEMB 9004-170) should be classified as a new species, for which the name Deinococcus rubellus sp. nov. is proposed.

Bacillus piscis sp. nov., a novel bacterium isolated from the muscle of the antarctic fish Dissostichus mawsoni.

In this paper, a new bacterial strain designated as 16MFT21T is isolated from the muscle of a fish caught in the Antarctic Ocean. Strain 16MFT21T is a Gram-staining-positive, catalase-oxidase-positive, rod-shaped facultative-aerobic bacterium. The phylogenetic analysis that is based on the 16S-rRNA gene sequence of strain 16MFT21T revealed that it belongs to the genus Bacillus in the family Bacillaceae in the class Bacilli. The highest degrees of the sequence similarity of the strain 16MFT21T is with Bacillus licheniformis ATCC 14580T (96.6%) and Bacillus sonorensis NBRC 101234T (96.6%). The isolate formed a pale-yellow pigment, and it grew in the presence of 0% to 10% (w/v) NaCl (optimum at 2% NaCl), a pH of 6.0 to 10.0 (optimum pH from 7.0 to 8.0), and from 4°C to 30°C (optimum at 30°C). The major polar lipids consist of diphosphatidylglycerol (DPG) and phosphatidylglycerol (PG). The predominant fatty acids are iso-C15:0, anteiso-C15:0, iso-C17:0, and anteiso-C17:0. The main respiratory quinone is menaquinone-7 (MK-7), and based on the use of the meso-diaminopimelic acid as the diagnostic diamino acid, the peptidoglycan cell-wall type is A1γ. Based on the phylogenetic, phenotypic, and chemotaxonomic data, strain 16MFT21T (=KCTC 18866T =JCM 31664T) for which the name Bacillus piscis sp. nov. is proposed should be classified as a new species.

Accumulation of PAHs and synthetic musk compound in minke whales (Balanoptera acutorostrata) and long-beaked common dolphins (Delphinus capensis) from Korean coastal waters.

Information on the occurrence and accumulation profiles of polycyclic aromatic hydrocarbons (PAHs) and synthetic musk compounds (SMCs) in marine mammals is scarce. In the present study, we recorded the concentrations and profiles of PAHs and SMCs in liver tissue and blubber from minke whales and common dolphins from Korean coastal waters. The overall concentrations of PAHs and SMCs in blubber from both cetacean species were approximately three to five times higher than those in liver tissues. Residue levels of PAHs were lower, whereas levels of SMCs were relatively higher than those reported in other studies. Lack of species- and sex-dependent differences in the concentrations of PAHs and SMCs were found. Naphthalene and 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-r-2-benzopyran (HHCB) were predominant compounds in all the samples for PAHs and SMCs, respectively. The concentrations of PAHs and SMCs were significantly correlated with each other, but were not correlated with body size of cetaceans. The present data provide valuable information on the exposure of Korean cetaceans to PAHs and SMCs.

Occurrence and accumulation features of polycyclic aromatic hydrocarbons and synthetic musk compounds in finless porpoises (Neophocaena phocaenoides) from Korean coastal waters.

Reports of the occurrence and accumulation patterns of polycyclic aromatic hydrocarbons (PAHs) and synthetic musk compounds (SMCs) in marine mammals are scarce. In this study, the concentrations and accumulation profiles of PAHs and SMCs were determined in blubber from finless porpoises in Korean coastal waters. Total concentrations of PAHs and SMCs ranged from 6.0 to 432 (mean: 160) ng/g lipid weight and from 17 to 144 (mean: 52) ng/g lipid weight, respectively. Residue levels of PAHs were lower than those reported from other studies, while residue levels of SMCs were relatively higher than those reported in other studies. Naphthalene was the most abundant PAH and HHCB was the dominant SMC observed in finless porpoises. The concentrations of PAHs and SMCs were not correlated with each other, but were significantly correlated within the same chemical groups. No correlations were found between body size and residue levels of PAHs and SMCs.

Accumulation of butyltin compounds in cetaceans from Korean coastal waters.

Data on the occurrence and accumulation profiles of butyltins (BTs), including tributyltin (TBT), in marine mammals are scarce. This is the first study to investigate residue levels and accumulation patterns of BTs in cetaceans from Korean coastal waters. The total concentrations of BTs (sum of mono- to tri-butyltins) in minke whales (Balaenoptera acutorostrata) and long-beaked common dolphins (Delphinus capensis) ranged from 15.7 to 297 ng/g wet weight (mean: 100 ng/g wet weight) and from 59.0 to 412 ng/g wet weight (mean: 228 ng/g wet weight), respectively. Dibutyltin (DBT) accounted for 63% of the total BTs in all cetacean samples. Significant species-specific differences in BT concentrations, possibly due to the differences in their habitat and diet, were found between the two cetacean species. The concentrations of DBT and TBT in most cetacean samples exceeded the threshold value for cytotoxic effects in cetaceans, implying potentially adverse health risks from exposure to BTs.

Contamination status and accumulation features of PCDDs, PCDFs and dioxin-like PCBs in finless porpoises (Neophocaena phocaenoides) from Korean coastal waters.

Data on the concentrations and accumulation profiles of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (DL-PCBs) in cetaceans are scarce. In this study, concentrations and accumulation profiles of PCDD/Fs and DL-PCBs were measured in the blubber of finless porpoises (Neophocaena phocaenoides) collected from Korean coastal waters. Total dioxin-like toxic equivalent (TEQ) concentrations (6.5-31 pg/g lipid weight) in finless porpoises were lower than those reported for cetaceans and pinnipeds from other countries. Significant gender-specific differences were found in the concentrations and accumulation profiles of PCDD/Fs and DL-PCBs and this difference was associated with maternal and lactation transfer of contaminants from mature females to their fetus. All of the PCDD/F homologue groups were detected in all of the samples and the proportions of PCDFs were higher than those of PCDDs. The dominant congeners found in finless porpoise blubber were 2,3,4,7,8-PeCDF, 1,2,3,4,7,8-HxCDF and OCDD for PCDD/Fs and PCB 118 for DL-PCBs. The accumulation profiles of PCDD/Fs in finless porpoise in our study were different from those found for cetaceans from other countries. Total TEQ levels in finless porpoises in Korea were below the suggested threshold values for adverse health effects in marine mammals.