• Korean Journal of Food Science and Technology
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• v.49 no.4
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• pp.390-395
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• 2017

The antibacterial activity of ethanol (99.9%) extracts from marine micro-algae, namely, Mixed A (Pavlova sp., Thalassiosira weissflogii, Tetraselmis suecica and Isochrysis galbana were mixed with 1:1:1:1 ratio), Chlorella vulgaris, Nannochloropsis oculata and Chaetoceros calcitrans were estimated against food-borne bacteria, namely, Escherichia coli, Salmonella Typhimurium, Staphylococcus aureus and Bacillus cereus. The extracts from these marine micro-algae showed potent antibacterial activity against all tested bacteria by the paper disk method. The extracts from C. vulgaris showed the strongest antibacterial activity against E. coli with minimum inhibitory concentration (MIC) of 0.62 mg/mL, and minimum bactericidal concentration (MBC) of 2.50 mg/mL. The extract from C. vulgaris contained 2 active compounds, 38.8% linoelaidic acid and 30.0% phytol. These results indicated that the ethanol extract from C. vulgaris may be a putative natural antibacterial agent against food-borne bacteria.

• Journal of Aquaculture
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• v.21 no.3
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• pp.167-171
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• 2008

Common co-existing organism Euplotes (Ciliate, Protozoa) well often observed in the rotifer mass culture tank of marine fish larval rearing stations. Ciliate protozoa (Euplotes) competed to condensed food (micoralgae, Nannochloropsis oculata) with rotifer (Brachionus rotundiformis). As results, rotifer density was rapidly decrease, and what is more, the rotifer was wiped out by dominant bacteria species at that time.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.1
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• pp.56-62
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• 2009

Feeding regimens was investigated for the growth and survival rate of juvenile Maroon clownfish (Premnas biaculeatus) in order to establish a seed production technique for this fish. Three types of feeding regimens were used, and growth and survival were highest under the following regimen: rotifer from day 0, Artemia from day 4, copepod from day 9 and artificial food from day 15, respectively (P<0.05). The average body lengths of the larvae were $6.76{\pm}0.55\;mm$, $7.63{\pm}0.50\;mm$ and $7.33{\pm}0.43\;mm$ in the Nannochloropsis oculata, Isochrysis galbana and control treatments conducted with 3 larvae/L, respectively (P<0.05). There were significant differences in larval growth between the treatments and controls conducted with 6 larvae/L and 9 larvae/L, respectively (P<0.05) but there was no significant difference between the N. oculata and I. galbana treatments (P>0.05). There were no significant differences in larval growth between the treatments at densities of 3-9 larvae/L (P>0.05). At highest density level, the larvae reared in I. galbana had the highest survival rate whereas survival was lowest in the control.

• Journal of Plant Biotechnology
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• v.44 no.4
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• pp.462-471
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• 2017

Thiamine pyrophosphate (TPP), the active form of thiamine is a cofactor for enzymes involved in central metabolism pathways. However, it is also known to have a role as a stress signaling molecule in response to environmental changes. Anabaena sp. and N. oculata are microorganisms which are abundantly found in Malaysia's freshwater and marine ecosystem. However, not much studies have been done especially in regards to thiamine biosynthesis. This work aimed to amplify of gene transcripts coding for thiamine biosynthesis enzymes besides looking at the expression of thiamine biosynthesis genes upon stress application. Various stress inducers were applied to the cultures and RNA was extracted at different time points. The first two genes, ThiC and ThiG/Thi4 encoding enzymes of the pyrimidine and thiazole branch respectively in the thiamine biosynthesis pathway were identified and amplified. The expression of the genes were analysed via RT-PCR and the intensity of bands were analysed using ImageJ software. The results showed up to 4-fold increase in the expression of ThiC and ThiG gene transcript as compared to control sample in Anabaena sp. ThiC gene in N. oculata showed an expression of 6-fold higher as compared to control sample. In conclusion, stresses induced the expression of the gene coding for one of the most important enzymes in thiamine biosynthesis pathway. This is an agreement with the hypothesis that overexpression of thiamine is crucial in assisting plants to combat abiotic stresses.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.4
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• pp.467-473
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• 2016

Several of our recent studies have focused on mass production of the marine Cladoceran Diaphanosoma celebensis, which can serve as a feed substitute for Artemia nauplii in the culture of larval marine fish. We compared the growth and survival rates of tiger puffer Takifugu rubripes fed D. celebensis with those fed Artemia. The group fed D. celebensis showed an increase in growth from 0.10 g to 1.78 g, while the group fed enriched Artemia had a growth from 0.10 g to 0.92 g. The survival rate of fish fed D. celebensis was 86.7% while that of fish fed enriched Artemia was 51.1%, indicating that the former group was superior to the latter both in growth and survival rate. Fatty acid analysis revealed that D. celebensis fed Nannochloropsis oculata and Schizochytrium sp. had an eicosapentaenoic acid (EPA) content of 16.42% and a docosahexaenoic acid (DHA) content of 3.93%. Meanwhile, juvenile tiger puffer fed D. celebensis had an EPA content of 9.12% and a DHA content of 10.69%. Juvenile tiger puffer fed D. celebensis had a similar n-3 highly unsaturated fatty acid content to that of tiger puffer fed enriched Artemia which had an EPA content of 5.82% and a DHA content of 15.90%, indicating that no additional enrichment was required.

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.2
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• pp.315-322
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• 2016

This study determined the optimum microalgae species and concentration for growth of small rotifer Proales similis, in community cultures by feeding it several different foods. Four single trials (Tetraselmis suecica, TET; Isochrysis galbana, ISO; Nannochloropsis oculata, NAN; freshwater Chlorella vulgaris, CHL) were conducted at 5 psu and $25^{\circ}C$. The maximum density and specific growth rate (SRG) were highest for rotifer fed CHL reaching 1,075 individuals (inds.)/mL and 0.83 respectively. By contrast, other foods of ISO, NAN and TET resulted in poor growth rates and maximum density. In the freshwater C. vulgaris experiments examining a range of 0.05 to $8.8mg/10^4rotifers$, the growth of rotifer tended to decrease with the amount of supplement. The maximum density and SGR of females was highest at 910 inds./mL and 0.55 respectively, at $0.05mg/10^4rotifers$. These results suggest that the best microalgae species for the culture of P. similis is freshwater C. vulgaris and the optimum concentration is $0.05mg/10^4rotifers$.

• Fisheries and Aquatic Sciences
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• v.26 no.8
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• pp.470-481
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• 2023

Algal overgrowth in shrimp culture ponds can affect the quality of the aquatic environment, thereby adversely affecting the shrimp and causing economic losses. The objective of this study was to evaluate the variation in phytoplankton composition in intensive shrimp ponds in Bac Lieu province, Vietnam. Phytoplankton samples were collected in three black tiger shrimp (Penaeus monodon) ponds and three whiteleg shrimp (Litopenaeus vannamei) ponds. The collected data were analyzed using SPSS and canonical correlation analysis softwares. In total, 75 species of phytoplankton were recorded in black tiger shrimp ponds and 64 species in whiteleg shrimp ponds. Diatoms had the highest species diversity with 29-30 species (39%-47%), followed by green algae with 9-19 species (14%-25%); species numbers of other phyla varied from 5-12 (8%-16%). The total number of phytoplankton species throughout the study varied from 34-50 species. Algal density was relatively high and ranged from 497,091-2,229,500 ind./L and 1,301,134-2,237,758 ind./L in black tiger shrimp and whiteleg shrimp ponds, respectively. The diatom density tended to increase during the final stage of the production cycle in black tiger shrimp ponds. Blue-green algae and dinoflagellates also increased in abundance at the end of the cycle, which can affect shrimp growth. Diatoms were significantly positively correlated with pH, salinity, total ammonia nitrogen, and nitrate (NO₃^-) concentrations (p < 0.05). Blue-green algae and dinoflagellates were positively correlated with salinity, phosphate (PO₄^3-), and NO₃^-. Algal species diversity was lower in the whiteleg shrimp ponds than in the black tiger shrimp ponds. Several dominant algal genera were recorded in the shrimp ponds, including Nannochloropsis, Gyrosigma, Chaetoceros, Alexandrium, and Microcystis. The results of this study provide basic data for further investigations, and they contribute to the management of algae in brackish-water shrimp ponds.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.1
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• pp.66-69
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• 2000

The common harpacticoida copepod species Tigriopus japnnicus was often obseued in the mass culture of marine rotifer tanks of sea farming stations. In this study, we investigated the co-existing effect of T. iaponicus to the rotifer Brachionus rotundiformis population growth. The culture conditions as temperature, salinity, culture volume, photo period, culture period and observation interval were 25{\circ}C, 22ppt, 40ml, 12L:12D, 16 deys$ and every two days during the experimental period, respectively. Nannochloropsis oculata was used as the food for the two testing organisms. After counting the growth of rotifer and copepod, they were transferred to new culture tank with N. oculata at the density of $7{times}10^5\;cells/ml$. The population growth of B. rotundiformis was suppressed by T. japonicus when these two organisms were mix-cultured comparing to single culture of B. rotundiformis. But population growth of T, japomcus was not affected by the presence of B. rotundiformis. The interspecific relationships of prey-predation and food competition were not observed in the combination culture of rotifer B. rotundiformis and copepod T japonicus.

• Journal of Aquaculture
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• v.11 no.1
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• pp.99-103
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• 1998

Artemia often observed as a co-existing organism in the mass culture tank of marine rotifer. The rotifer and Atremia are commonly used as food organisms in the marine fish larvae rearing. In this study, interspecific relation between the rotifer Brachionus rotundiformis (formely called S-type) and anostracan Artemia of the two developmental stages (0 and 19 day old after hatching) were investigated in the larboratory. The population growth of B. rotundiformis and one of the stage (nauplius or adult) of Artemia in mixed culture was compared with that of each single species culture. Culture period was 16 days. Every two days, the number of organisms in each species was counted and transferred to a fresh medium containing $7{\times}10^5$cells/ml of food Nannochloropsis oculata. Culture volume, temperature, salinity and photoperiod were set at 40ml, $25^{\circ}C.$, 22ppt and 24h all dark except to observation time, respectively. The rotifer population growth was greatly decreased by co-existence with Artemia. The coexisting Artemia suppressed the rotifer population growth due to it's high filtering speed for food (N. oculata). This study suggested that contamination by Artemia must be prevented for the stable rotifer production in the rotifer mass culture tank.

• Journal of Aquaculture
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• v.13 no.4
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• pp.277-284
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• 2000

Rabbitfish hatchlings were given a mixed food of rotifers (Brachionus rotundiformis) and trochophore larvae of oyster. Only the oyster-trochophore larvae were found in the gut of 62-h old fish larvae. The fish larvae, fed on rotifer and ciliate alone did not survive. However, their survival increased to 3.3 % on the 10th day after hatching, when trochophore was supplemented. Corresponding with the accelerated growth, the number of rotifers consumed increased from 11 in a 5-day old fish to 165 in a IS-day old fish. In a field ecosystem containing live diatom, Nannochloropsis oculata, rotifers and copepods, fish larvae were shocked and the oyster's trochophore larvae were fed from 2 to 7 days after hatching. A total of 76,000 seedling were produced after 50 days of hatching with 12.7 % survival. Mean total length and body weight were 65.6 mm and 3.4 g, respectively. Growth of body length (BL), body height (BH), body weight (BW) and head length (HL) as a function of the total length (TL) showed regressional relationships as follows; BL=0.8565 TL+0.0852 ($t^2$=0.9996); BH=0.3207 TL - 0.5052 (($t^2$=0.9641) BW=0.0652 TL2.3508 (($t^2$=0.9925); HL=0.2595 TL - 0.1898 (($t^2$=0.9901)