• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.2
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• pp.160-164
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• 1999

Algicidal activities of Alteromonas sp. SR-14 against Chaetoceros calcitrans were investigated at various culture conditions. The algicidal activity by Alteromonas sp. SK-14 was dependent on temperature. In mixed culture of C, calcitrans and Alteromonas sp. SR-14 at various temperatures, the algicidal activity of Alteronzonas sp. SR-14 was the highest at $20^{\circ}C$, but not showed algicidal activity above $25^{\circ}C$. With the inoculation of $10^4$ cells/ml of C. calcitrans, the diatom could not grow at the microalgal culture condition until 15 days by the simultaneous inoculation of less than 10 cells/ml of Alteromonas sp. SR-14. Alteromonas sp. SR-14 showed the strongest algicidal activity against logarithmic phase cells of C. calcitrans. During the mixed culture of C. calcitrans and Alteromonas sp. SR-14, supplementation of Conwy medium nutrients, changes of light intensity with 1,300$\~$4,600 lux and agitation with 200 rpm did not affect the algicidal activity.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.2
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• pp.155-159
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• 1999

Marine bacteria inhibiting the growth of the diatom, Chaetoceros calcitrans were screened from seawater samples collected at south coast of Korea in 1996. Six strains were isolated from those samples. Among them, a bacterium SR-14 strain had the strongest inhibition activity against the alga. The selected SR-14 strain was identified as an Alteromonas sp. (supposed to be Alteromonas colwelliana) according to its biochemical results. Alteromonas sp. SR-14 was able to grow in raw seawater, aged seawater, Conwy medium for culture of microalgae and C. calcitrans culture filtrate. The host ranges of Alteromonas sp. SR-14 were C. calcitrans, C. muclleri and C. negracile among 10 species of diatom. All of the Chaetoceros spp. tested were inhibited by the Alteromonas sp. SR-14, However, the growth of the other genera in Bacillariophyceae was not inhibited.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.50 no.4
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• pp.447-454
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• 2014

The marine microalgae Chaetoceros calcitrans was cultured under a fluorescent lamp (CON) and light-emitting diodes (LEDs) of various wavelengths (blue, LB; red, LR; green, LG; white, LW); changes in growth, fucoxanthin, chlorophyll-a, amino acid and fatty acid profiles were investigated. LR-exposed cultures exhibited the highest specific growth rate (SGR) (0.34), whereas LG-exposed cultures showed the lowest SGR (0.26). After cultivation for 10 days, the maximum dry cell weight (g/L) of LR-exposed cultures was significantly higher than that of those exposed to other light conditions (LR${\geq_-}$CON>LB${\geq_-}$LW${\geq_-}$LG). Eicosapentaenoic acid (EPA) levels were significantly higher in CON-exposed cultures compared to those exposed to LW (P<0.05), with no marked difference compared to those exposed to LB, LR and LG (P>0.05). The fucoxanthin content was highest in LB-exposed cultures ($6.3{\mu}g/mL$), whereas LW showed the lowest ($3.6{\mu}g/mL$; P<0.05). Chlorophyll-a content was highest in cultures exposed to LB compared to other light sources. These results suggest consistent differences in growth and biochemical composition after exposure to light of different wavelengths.

• The Korean Journal of Malacology
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• v.25 no.1
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• pp.35-40
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• 2009

The trumpet shell Charonia sauliae is an endangered and valuable species with potential for aquaculture. For artificial propagation of C. sauliae, the effects of three different food microalgae on the development, growth, and survival rate of the larvae and spat were investigated. For the larval feeding experiments, we utilized six microalgae species as food sources, namely Pavlova lutheri, Tetraselmis suecica, Nannochloris oculata, Isochrysis galbana, Chaetoceros calcitrans, and Phaeodactylum tricornutum; for the larval and spat growth and survival experiments, we utilized T. suecica, C. calcitrans, and P. tricornutum. The results showed that the temporal digestion index (TDI) for the veliger larvae was significantly different for C. sauliae fed the different microalgae species (p < 0.05), that the T. suecica, C. calcitrans, and P. tricornutum cultivars were better suited for larval consumption (p < 0.05), and that the growth and survival of the larvae and spat were significantly influenced by food type, specifically P. tricornutum (p < 0.05). Further research is needed to evaluate the effects of other microalgae species, different algal concentrations, and biochemical composition on the growth and survival of C. sauliae.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.1
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• pp.24-29
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• 2003

In the previous reports, the authors isolated two strains of marine bacteria, Shewanella sp. SR-14, which has Chaetonros sp. growth inhibition activity, and Vibrio alginolyticus, that did not affect growth of the alga. In the present study, fatty acid compositions of diatoms, Chaetoceros calcitrans and Skeletonema costatum, and marine bacteria, Shewanella sp. SR-14 and V. alginolyticus, were analyzed. Changes of fatty acid composition in the diatoms grown with the marine bacteria were also determined. Major fatty acids of Sbewanella sp. SR-14 were 16:1n-7 $(29.4\%)$ and 16:0 $(19.2\%)$ during incubation in peptone broth at $20^{\circ}C$ for 3 days. The compositions of V. alginolyticus detected were 16:0 $(23.7\%),$ 16:1n-7 $(27.7\%)$ and 18:1n-7 $(21.0\%).$ C. calcitrans consisted of 16:1n-7 $(33.3\%),$ 16:0 $(27.1\%)$ and 14:0 $(12.1\%).$ S. costatum mainly contained 16:1n-7 $(28.9\%),$ 16:0 $(21.6\%)$ and 20:5 $(19.8\%).$ When halves of cell numbers of C. calcitrans were moribund cells by Shewanella sp. SR-14, the C. calcitrans and S. costatum simultaneously cultured with the bacteria were harvested by filtration with GE/D glass microfibre filter. In the fatty acid composition of both diatoms, saturated fatty acid contents in both diatoms grown with Shewanella sp. SR-14 were decreased, but unsaturated fatty acid contents were increased. The differences were greater in C. calcitrans than those in S. costatum. During the growth of diatoms with V. alginolyticus, C. calcitrans showed increase of saturated fatty acid contents and decrease of unsaturated fatty acid contents; however, S. costatum did not show sharp difference in fatty acid content. In this study, Shewanella sp. SR-14, which showed growth inhibition activity against C. calcitrans, influenced on the changes of fatty acid contents in the diatom. It was suggested that increased unsaturated fatty acid was synergistically activated algal growth inhibition activity of Shewanella sp. SR-14.

• The Korean Journal of Malacology
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• v.27 no.3
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• pp.175-180
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• 2011

The investigated amounts according to microalgae for stable supply of artificial seed of the hard clam, Meretrix petechialis and also observed the effect according to the repower of the microalgae after the specified period starvation. The stage of specimen used in the test was the D-shaped larva. The microalgae was Chaetoceros calcitrans, Isochrysis galbana and Nannochloris oculata. When the mixture of Chaetoceros calcitrans, Isochrysis galbana and Nannochloris oculata or alone C. calcitrans as food was supplied with 3,000-5,000 cells/ind., it turned to be the most effective. When the food was provided after starvation for some period, the shell length of D-shaped larva was grown to over $192.5{\mu}m$ at fourth day from the initial feeding. The survival rate tended to be lower, the longer the starvation period.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2002.10a
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• pp.137-138
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• 2002

최근 세균을 이용한 적조 방제연구가 활발히 진행되면서 해양에서 다수의 미세조류 저해균이 분리되고 있다. 전보에서 저자들은 규조류 Chaetoceros spp.의 생육을 저해하는 해양세균 Shewanella sp. SR-14를 분리하였으며, 이 균은 대사산물을 생성하여 그 생육을 저해하는 것으로 보고한 바 있다. 그런데 Shewanella sp. SR-14에 의한 Chaetoceros calcitrans의 생육저해는 대사산물(배양여액)만을 사용한 경우보다 세균이 공존하는 경우에 그 활성이 휠씬 강하여 세균이 생성하는 저해물질에 의한 것으로만 이해하기 어려웠으며, 다른 미지의 기구가 관여하고 있을 가능성이 시사되었다. (중략)

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2000.05a
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• pp.487-488
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• 2000

Genomic DNA was isolated from the marine microalgae representing genetic characteristics and genomic polymorphisms by polymerase chain reaction amplification of DNA as arbitrary primers. The electrophoretc analysis of PCR-RAPD products showed hig levels of variation between different genus and little variation between different species. Outer of these primers, 6 generated 248 highly reproducible RAPD markers, producing almost seven polymorphic bands per primers. The degree of similarity frequency between Chaetoceros gracilis and Chaetoceros calcitrans species showed 90％ as calculated by sharing analysis. The RAPD polymorphism generated by this primer may be used as a genetic marker for genus or species identification in important marine microalgae. (omitted)

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.5
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• pp.430-434
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• 2001

The algicidal activity of Shewanella (formerly Alteromonas) sp. SR-14 against diatom, Chaetoceros calcitrans was reported in our previous papers. In this study, the effect of Vibrio alginolyticus on the algicidal activity of Shewanelia sp, SR-14 was examined under the optimum algicidal conditions, i.e., temperature ($21\pm1^{\circ}C$), light intensity (4,000 lux), and light: dark cycle (12 hour: 12 hour). Shewanella sp. SR-14 grew well in the presence or the absence of V. alginolyticus in Conwy medium. Algal growth was only inhibited by Shewanella sp. SR-14. V. alginolyticus did not show the algicidal activity, Growth of C. calcitrans increased synergistically with growth of V. alginolyticus. When the initial inoculum of V. alginolyticus was only 1 log cycle higher than that of Shewanella sp. SR-14, the effect of V. alginolyticus on the algicidal activity of Shewanella sp. SR-14 was insignificant during incubation of mixed culture, i.e., two bacterial species and the alga. However, when V. alginolyticus dominated Shewanella sp. SR-14 by 3 log cycles of bacterial counts, it was found that the strain SR-14 could not inhibited growth of C. calcitrans up to 5 days of incubation.

• Journal of Food Hygiene and Safety
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• v.14 no.3
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• pp.270-276
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• 1999

In previous reports, the authors isolated the algicidal marine bacterium, Alteromonas sp. SR-14 and demonstrated its growth inhibition of diatom, Chaetoceros calcitrans (C. calcitrans). In this paper, we studied the effects of cell free culture filtrate of Alteromonas sp. SR-14 on the growth of C. calcitrans, and the characteristics of the algal growth inhibition substance. The culture filtrate of Alteromonas sp. SR-14 grown in peptone broth showed growth inhibition activity against C. calcitrans. The reasonable culture conditions of the bacterium for producing of algal growth inhibition substances were $15~20^{\circ}$ in temperature, 7.0-9.0 in pH and $23~30{\textperthousand}$ in salinity, respectively. The algal growth inhibition activity of culture filtrate was increased from stationary phase in growth curve of Alteromonas sp. SR-14. The molecular weights of algal growth inhibition substances produced by Alteromonas sp. SR-14 were ranged about from 3 KDa to 12 KDa. Among the substances, less than 10 KDa fraction were stable by heating at $100^{\circ}$ for 10 minutes, while more than 10 KDa fraction were heat labile. According to the experimental results, the algal growth inhibition substance produced by the bacterium was not a single compound.