In this study, δ-aminolevulinic acid (δ-ALA), a plant growth promoter, production with E. coli recombined with microalgae Isochrysis galbana and Chlorella sp. was added without (control), f/2 medium, δ-ALA 20 ppm, f/2 medium +δ-ALA 1, 10, 20 ppm was added and cultured for 12 days to investigate the number of cells and the specific growth rate (SGR). In I. galbana, a haptophytes, both the cell number and SGR were significantly higher in the experimental group cultured with f/2 medium at 2, 3, 5 day (P < 0.05). In the δ-ALA added group, f/2A10 with 10 ppm of δ-ALA added to f/2 medium was significantly higher than in all groups expect f/2A20 at 5 day (P < 0.05). In Chlorella sp., a chlorophyta, the cell number and SGR of f/2A1 were significantly higher than those of all groups except f/2A20 (it was excluded from the culture due to a test error) at 1 day (P < 0.05). At 2, 3 and 5 day, all of the δ-ALA added groups showed significantly higher cell numbers and SGR than the control and f/2 groups (P < 0.05). At 8 day, f/2A1 was significantly higher than that of all the groups including the δ-ALA-added group (P < 0.05), and continued until the 12th day. Therefore, δ-ALA production with recombinant E. coli had little growth promoting effect in I. galbana, but showed a growth promoting effect in Chlorella sp..
A multiplex PCR primers (the species-specific primers) set using molecular biological methods targeting four species of ark shells (Anadara kagoshimensis, Tegillarca granosa, Anadara broughtonii and Cucullaea labiata) distributed in Korea were built, and a rapid and accurate species identification method was developed. The species-specific primer was designed within the nucleotide sequence of about 573 bp corresponding to the cytochrome c oxidase subunit 1 (co1) gene region of mitochondrial DNA, and considering the single nucleotide polymorphism (SNPs) representing inter-species variation excluding intra-species variation, it was designed with an interval of 80-100 bp for each species. As a result, it was confirmed that species-specific bands were formed in the order of A. kagoshimensis (160 bp), T. granosa (245 bp), A. broughtonii (351 bp), and C. labiata (471 bp). In addition, in order to measure the limit of multiplex PCR amplification according to the concentration of genomic DNA (gDNA) and the number of PCR amplification repetitions, 15 experimental groups were divided and measured. As a result, when the number of amplification repeats was 25 cycles, the concentration of gDNA was detected down to a minimum of 1 ng/μl. Therefore, the multiplex PCR primer set for four species of ark shells developed in this study is expected to be of great help in accurately and rapidly identifying species in the field, it is thought that economic damage and academic errors caused by misidentification can be prevented.
The method for ploidy verifications is necessary for efficient research and development of triploid abalone, Haliotis discus hannai. The various methods such as flow cytometry, karyotyping, and particle size analysis have been used to confirm ploidy. However, this method provides only an approximate estimation of the ploidy level and measuring cellular DNA content is not only time consuming, but also costly and labor intensive. In this study, a quick and accurate method for ploidy verification of triploid and diploid abalone, H. discus hannai, was developed using multiplex polymerase chain reaction (PCR) system for molecular microsatellite markers. The multiplex PCR system including five microsatellites markers from Pacific abalone, H. discus hannai, consisting of di, tri, tetra and pentanucleotide repeat units, is developed. The multiplex PCR was able to verify the ploidy of 14 triploid abalone with 100% accuracy, In this results suggest that multiplex PCR system may be a useful tool in verification of triploid abalone.
In this study, The influence of pollutants flowing in from the vicinity of the Sea Areas of Shellfish production for export got calculated by investigating the type, shape and radius of pollutants to determine how much it affects the sea area. In addition, the sanitary condition of seawater and shellfish in the Narodo Sea area was investigated in accordance with Korean, US and EU regulations to ensure the safety of clams, which are the main production shellfish in Narodo. There were 179 sources of pollution in the waters near Narodo, and a total of 28 places where the flow rate was confirmed. As a result of analyzing samples from January 2018 to December 2020 at 4 sites selected as major land pollution sources, it was found that the concentration of fecal coliform intermittently high in the final discharge outlets of Ikgeum Village sewer, Dohwacheon and Deokjungcheon was found. It was confirmed that the radius of influence was about 2.5 km. From January 2018 to December 2020, the water quality at 27 sites and clams, the main production of shellfish produced in the water of Narodo, were investigated. The values of fecal coliform, E. coli and general bacterial counts of clam were confirmed to be < 18-490, < 18-490 MPN/100 g and 10-3,600 CFU/g, respectively. The results of the investigation at 27 seawater points at the same time were confirmed that the range of fecal coliform coli was < 1.8-27 MPN/100 mL. Moreover, the range of geometric mean and 90th percentile was analyzed to be < 1.8-2.3 and < 1.8-5.3 MPN/100 mL, respectively. Therefore, According to this research, It is believed that it can be used as basic scientific data to manage pollutants and ensure the safety of shellfish by evaluating how much major land pollutants around Narodo of Goheung bacteriologically affect the water quality and shellfish in the sea area.
Seawater samples was carrind out at 9 stations were selected once a month in January, April, July, and October 2019 and 2020, respectively. In this study, it was investigated for physicochemical experiments and microbial experiments in the waters of Goseong Bay. The mean temperature was 5.44-25.20℃, the mean salinity was 28.30-33.07 psu, and the mean pH was 8.00-8.48. The mean DO of the Goseong Bay was 6.88-10.90 mg/L, In Goseong Bay, microbiological experiments were < 1.8-130.0 MPN/100 mL (total coliform) and < 1.8-23 MPN/100 mL (fecal coliform). In July 2020, high cumulative rainfall was confirmed, physicochemical factors of seawater were affected by rainfall. 2020 fecal coliform was significantly higher than that of 2019. In particular, the stations 5, 6, and 7 showed high figures, which are believed to be due to Daedok Stream and Wolpyeong Stream. When the cumulative rainfall was less than 55 mm, the effect on the sea area was insignificant, and when it was more than 185 mm, it was found to have an effect on the sea area. Compared to Jaraman Bay and Saryangdo Island, which are nearby waters, it can be seen that Goseong Bay belongs to blue belt, Goseong Bay does not exceed the standard of 14 MPN/100 mL (fecal coliform).
To investigate the applicability on abalone culture, 14 brass nets were installed into sea net cages at Nowha-do and Gunnae-ri in Wando, Korea. No statistically significant growth was observed in shell size and weight but in fatness at the brass net. A significant decrease was observed in mortality only in Gunnae-ri, which geologically characterized the closed water features. No significant differences were observed in species and biomass in bio-fouling organisms on the surface of abalone shells between both net types and waters. All metal contents were negligible without differences between net types but significant increase of copper content in the meat from Gunnae-ri, which indicated the necessity of monitoring in copper dynamics especially when the brass net installed in closed waters. A significant increase of taste value in brass net abalone resulted from increases of Taurine in viscera and Arginine in meat. The improvement of fatness, mortality, and taste value indicated that the brass net could improve physiological function through improved water exchange from its antifouling properties. Despite the necessity of risk management on copper dynamics in closed waters, our results suggested that the brass net could be an alternative technique for abalone culture to increase cultural productivity.
This study researched seed production technology for bivalvia soft-shell clam. The result of the experiment on the fertilized egg development showed the fertilized egg was 80.8 mm, and it took 29 hours to reach the stage of the D-shaped larvae at a water temperature of 17°C. The first feeding of larva took place 44 hours after fertilization. The D-shaped production of soft-shell clam fertilized eggs was in the range of 17-23℃ in water temperature and 30-33℃-77-78% in salt concentration. Based on the experimental results, foot was formed at shell length 231.6 ± 10.6 μm around 15 days after fertilization according to the results of mass seed production at 17.2-24.5℃, 31.2-33.6%, and landing was completed at shell length 258.4 ± 10.6 μm around 20 days after fertilization. Plantigrade larvae reached average shell length 1 mm around 44 days after seed production, and an average of 3 mm around 66 days.
In this study, 65 strains were isolated from Surf clam and Tresus keenae. Among the isolated strains, Bacillus genus strains were used to select strains with good effects on organic matter decomposition ability, pathogenic bacteria antibacterial activity, digestion, absorption and larval growth. Biofilm formation, water purification and seedling effects were investigated using the selected strain. As a result of the study, it was confirmed that strain specificity exists in the formation of biofilms, water purification and seedling effects. The results of this study are expected to be usefully utilized in the shellfish aquaculture industry. In addition, the purpose of this study is to inform researchers that they should be interested in and do a lot of research.
The second part of the annotated and illustrated catalogue of species of the bivalve molluscan fauna of Jeju Island (Jeju-do) is based on original and literature data. The catalogue provides local distribution and taxonomic comments on bivalves and is supplemented with data on general distribution, habitats, and primary synonyms. This part includes 142 species belonging to 36 families (Lucinidae through Poromyidae), with original photographs for 76 species. Nineteen species are reported as new for Jeju Island, 9 species as new for Korea: Vasticardium subrugosum (G.B. Sowerby II, 1839), Fragum loochooanum Kira, 1959, Montacutona japonica (Yokoyama, 1922), Pristipagia ojiensis (Tokunaga, 1906), Donax cuneatus L., 1758, Sunetta kirai Huber, 2010, Pitar inflatus (G.B. Sowerby II, 1851), Dosinia cf. orbiculata Dunker, 1877, Pelecyora corculum (Römer, 1870), and 6 species have been reported in literature but were not included in the first molluscan catalogue of Jeju by Noseworthy et al. (2007); in total, 25 species are added to the Jeju fauna in this part. Odd literature records are discussed. In all, 248 species and 58 families of marine bivalve mollusks are currently known in Jeju-do.