• ALGAE
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• 제36권4호
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• pp.299-314
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• 2021

Some species in the dinoflagellate genus Alexandrium are bioluminescent. Of the 33 formally described Alexandrium species, the bioluminescence capability of only nine species have been tested, and eight have been reported to be bioluminescent. The present study investigated the bioluminescence capability of seven Alexandrium species that had not been tested. Alexandrium mediterraneum, A. pohangense, and A. tamutum were bioluminescent, but A. andersonii, A. hiranoi, A. insuetum, and A. pseudogonyaulax were not. We also measured the bioluminescent intensity of A. affine, A. fraterculus, A. mediterraneum, A. ostenfeldii, A. pacificum, A. pohangense, A. tamarense, and A. tamutum. The mean 200-second-integrated bioluminescence intensity per cell ranged from 0.02 to 32.2 × 10⁴ relative luminescence unit per cell (RLU cell^-1), and the mean maximum bioluminescence intensity per cell per second (BL_Max) ranged from 0.01 to 10.3 × 10⁴ RLU cell^-1 s^-1. BL_Max was significantly correlated with the maximum growth rates of Alexandrium species, except for A. tamarense. A phylogenetic tree based on large subunit ribosomal DNA (LSU rDNA) showed that the bioluminescent species A. affine, A. catenella, A. fraterculus, A. mediterraneum, A. pacificum, and A. tamarense formed a large clade. However, the toxicity or mixotrophic capability of these species was split. Thus, their bioluminescence capability in this clade was more consistent than their toxicity or mixotrophic capability. Phylogenetic trees based on LSU rDNA and the luciferase gene of Alexandrium were consistent except for A. pohangense. The results of the present study can provide a basis for understanding the interspecific diversity in bioluminescence of Alexandrium.

• ALGAE
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• 제36권1호
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• pp.25-36
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• 2021

The mixotrophic dinoflagellate Tripos furca causes red tides in the waters of many countries. To understand its population dynamics, mortality due to predation as well as growth rate should be assessed. Prior to the present study, the heterotrophic dinoflagellates Noctiluca scintillans, Polykrikos kofoidii, Protoperidinium steinii, and mixotrophic dinoflagellate Fragilidium subglobosum were known to ingest T. furca. However, if other common heterotrophic protists are able to feed on T. furca has not been tested. We explored interactions between T. furca and nine heterotrophic dinoflagellates and one naked ciliate. Furthermore, we investigated the abundance of T. furca and common heterotrophic protists in coastal-offshore waters off Yeosu, southern Korea, on Jul 31, 2020, during its red tide. Among the tested heterotrophic protists, the heterotrophic dinoflagellates Aduncodinium glandula, Luciella masanensis, and Pfiesteria piscicida were able to feed on T. furca. However, the heterotrophic dinoflagellates Gyrodiniellum shiwhaense, Gyrodinium dominans, Gyrodinium jinhaense, Gyrodinium moestrupii, Oblea rotunda, Oxyrrhis marina, and the naked ciliate Rimostrombidium sp. were unable to feed on it. However, T. furca did not support the growth of A. glandula, L. masanensis, or P. piscicida. Red tides dominated by T. furca prevailed in the South Sea of Korea from Jun 30 to Sep 5, 2020. The maximum abundance of heterotrophic dinoflagellates in the waters off Yeosu on Jul 31, 2020, was as low as 5.0 cells mL-1, and A. glandula, L. masanensis, and P. piscicida were not detected. Furthermore, the abundances of the known predators F. subglobosum, N. scintillans, P. kofoidii, and Protoperidinium spp. were very low or negligible. Therefore, no or low abundance of effective predators might be partially responsible for the long duration of the T. furca red tides in the South Sea of Korea in 2020.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2001년도 추계학술발표대회
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• pp.298-300
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• 2001

본 실험의 결과, H. pluvialis의 배양에 있어서 고농도의 $CO_2$를 공급함으로서 세포의 성장속도가 의미 있게 증가함을 알았고, 더불어 $CO_2$가 공급되는 경우, acatate 와 같은 유기탄소원이 오히려 세포의 성장을 저해함을 알 수 있었다.

• 미생물학회지
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• 제32권3호
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• pp.202-207
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• 1994

Bacillus megaterium ATCC 14945의 penicillin G acylase 유전자의 염기배열을 결정하였다. 이 유전자에는 2,406 염기쌍으로 이루어진 하나의 open reading frame이 존재하는데, 개시코돈의 5' 위쪽에서 Shine-Dalgarno 배열과 promoter로 여겨지는 부분을 발견하였으며, 종결코돈의 3' Synechocystis sp. PCC 6803으로부터 광활성종속영양으로 생장할 수 없는 돌연변이체 PRM1을 분리하였다. PRM1을 혼합영양으로 배양하였을 경우에는 생장속도가 Synechocystis 6803과 거의 같았다. 그러나 PRM1을 하루에 5 분만 빛을 조사하면서 광활성종속영양으로 배양하였을 경우에는 전혀 생장하지 못하였다. 이러한 결과는 PRM1이 종속영양으로 생장하는데 필요한 대사능력에 이상이 있는 것이 아니라 생장에 필요한 광신호 전이 체계에 이상이 있음을 시사한다. PRM1의 plasmid 양상, 균체의 absorption spectra, 세포 내부와 외부의 형태 등은 Synechocystis 6803과 유사하였으나 여러 세포들을 함께 얽어매는 부정형 점액성 물질을 형성하지 않는 점이 달랐다.

• ALGAE
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• 제31권1호
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• pp.17-31
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• 2016

To explore the feeding ecology of the newly described heterotrophic dinoflagellate Aduncodinium glandula in the family Pfiesteriaceae, its feeding behavior and prey species were investigated. Additionally, the growth and ingestion rates of A. glandula on the mixotrophic dinoflagellates Heterocapsa triquetra and Akashiwo sanguinea, its optimal and suboptimal prey, respectively were measured. A. glandula fed on prey through a peduncle after anchoring to the prey using a tow filament. A. glandula ate all algal prey and perch blood cells tested and had the most diverse prey species in the family Pfiesteriaceae. Unlike for other pfiesteriacean species, H. triquetra and A. sanguinea support the positive growth of A. glandula. However, the cryptophytes Rhodomonas salina and Teleaulax sp. and the phototrophic dinoflagellate Amphidinium carterae did not support the positive growth of A. glandula. Thus, A. glandula may have a unique kind of prey and its optimal prey differs from that of the other pfiesteriacean dinoflagellates. With increasing mean prey concentration, the growth rates of A. glandula on H. triquetra and A. sanguinea increased rapidly and then slowed or became saturated. The maximum growth rates when feeding on H. triquetra and A. sanguinea were 1.004 and 0.567 d⁻¹, respectively. Further, the maximum ingestion rates of A. glandula on H. triquetra and A. sanguinea were 0.75 and 1.38 ng C predator⁻¹ d⁻¹, respectively. There is no other pfiesteriacean species having H. triquetra and A. sanguinea as optimal and suboptimal prey. Thus, A. glandula may be abundant during blooms dominated by these species not preferred by the other pfiesteriacean dinoflagellates.

• ALGAE
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• 제31권3호
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• pp.257-266
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• 2016

Nitrogen is one of the most critical nutrients affecting cell growth and biochemical composition of microalgae, ultimately determining the lipid or carbohydrate productivity for biofuels. In order to investigate the effect of nitrogen sources on the cell growth and biochemical composition of the marine microalga Tetraselmis sp., nine different N sources, including NaNO₃, KNO₃, NH₄NO₃, NH₄HCO₃, NH₄Cl, CH₃COONH₄, urea, glycine, and yeast extract were compared at the given concentration of 8.82 mM. Higher biomass concentration was achieved under organic nitrogen sources, such as yeast extract (2.23 g L⁻¹) and glycine (1.62 g L⁻¹), compared to nitrate- (1.45 g L⁻¹) or ammonium-N (0.98 g L⁻¹). All ammonium sources showed an inhibition of cell growth, but accumulated higher lipids, showing a maximum content of 28.3% in ammonium bicarbonate. When Tetraselmis sp. was cultivated using yeast extract, the highest lipid productivity of 36.0 mg L⁻¹ d⁻¹ was achieved, followed by glycine 21.5 mg L⁻¹ d⁻¹ and nitrate 19.9 mg L⁻¹ d⁻¹. Ammonium bicarbonate resulted in the lowest lipid productivity of 14.4 mg L⁻¹ d⁻¹. The major fatty acids in Tetraselmis sp. were palmitic, oleic, linoleic and linolenic acids, regardless of the nutritional compositions, indicating the suitability of this species for biodiesel production.

• Journal of Microbiology and Biotechnology
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• 제21권10호
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• pp.1073-1080
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• 2011

In order to investigate and generalize the effects of carbon and nitrogen sources on the growth of and lipid production in Chlorella sp. 227, several nutritional combinations consisting of different carbon and nitrogen sources and concentrations were given to the media for cultivation of Chlorella sp. 227, respectively. The growth rate and lipid content were affected largely by concentration rather than by sources. The maximum specific growth was negatively affected by low concentrations of carbon and nitrogen. There is a maximum allowable inorganic carbon concentration (less than 500~1,000 mM bicarbonate) in autotrophic culture, but the maximum lipid content per gram dry cell weight (g DCW) was little affected by the concentration of inorganic carbon within the concentration. The lipid content per g DCW was increased when the microalga was cultured with the addition of glucose and bicarbonate (mixotrophic) at a fixed nitrogen concentration and with the lowest nitrogen concentration (0.2 mM), relatively. Considering that lipid contents per g DCW increased in those conditions, it suggests that a high ratio of carbon to nitrogen in culture media promotes lipid accumulation in the cells. Interestingly, a significant increase of the oleic acid amount to total fatty acids was observed in those conditions. These results showed the possibility to induce lipid production of high quality and content per g DCW by modifying the cultivation conditions.

• 대한환경공학회지
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• 제39권6호
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• pp.332-338
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• 2017

본 연구는 혼합영양생물인 Scenedesmus acuminatus의 최적배양조건을 찾기 위한 연구로서 최적 공기주입량, 아세테이트 주입량, $CO_2$ 주입에 대해 실험을 진행하였다. 공기주입량은 0.72 vvm에서 최대 비성장속도와 최대바이오매스 생산량을 얻을 수 있었으며, 0.3 M의 아세테이트를 주입하였을 때 최대 비성장속도와 최대바이오매스 생산량을 얻었다. 반연속배양에서는 추가로 $CO_2$ 주입이 배양에 미치는 영향을 파악하였다. $CO_2$ 주입 실험에서는 아세테이트로 50% 치환한 후에 최대비성장속도($0.460d^{-1}$)와 최대바이오매스 생산성($0.936gL^{-1}d^{-1}$)을 얻을 수 있었으며 이후 치환이 계속될수록 최대비성장속도와 최대바이오매스 생산성은 지속적으로 감소하였다. 공기주입 실험에서는 JM 배지로 배양할 때 가장 높은 비성장속도($0.381d^{-1}$)와 최대바이오매스 생산성($0.253gL^{-1}d^{-1}$)을 보여주었지만 이후 아세테이트를 함유한 배지로 50% 치환하였을 때 오히려 초기값보다 감소하는 것을 관찰하였다.

• Journal of Microbiology and Biotechnology
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• 제15권4호
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• pp.716-721
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• 2005

The role of an effective microbial species is critical to the successful application of biological processes to remove sulfur compounds. A bacterial strain was isolated from the soil of a malodorous site and identified as Burkholderia spp. This isolate was able to oxidize thiosulfate to sulfate, with simultaneous pH decrease and accumulation of elemental sulfur. The specific growth rate and the sulfate oxidation rate using the thiosulfate basal medium were $0.003 h^{-1}\;and\;3.7 h^{-1}$, respectively. The isolated strain was mixotrophic, and supplementation of $0.2\%$ (w/v) of yeast extract to the thiosulfate-basal medium increased the specific growth rate by 50-fold. However, the rate of sulfate oxidation was more than ten times higher without yeast extract. The isolate grew best at pH 7.0 and $30^{\circ}C$, and the sulfate oxidation rate was the highest at 0.12 M sodium thiosulfate. In an upflow biofilter, the isolated strain was able to degrade $H_2S\;with\;88\%$ efficiency at 8 ppm and 121/h of incoming gas concentration and flow rate, respectively. The cell density at the bottom of the column reached $3.2{\times}10^8$ CFU/(g bead) at a gas flow rate of 121/h.

• ALGAE
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• 제38권1호
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• pp.57-70
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• 2023

The mortality rate of red-tide dinoflagellates owing to predation is a major parameter that affects their population dynamics. The dinoflagellates Ansanella granifera and Ansanella sp. occasionally cause red tides. To understand the interactions between common heterotrophic protists and A. granifera, we explored the feeding occurrence of nine heterotrophic protists on A. granifera and the growth and ingestion rates of the heterotrophic dinoflagellate Gyrodinium dominans on A. granifera as a function of prey concentration and those of Oxyrrhis marina at a single high prey concentration. The heterotrophic dinoflagellates Aduncodinium glandula, G. dominans, Gyrodinium moestrupii, Luciella masanensis, Oblea rotunda, O. marina, Polykrikos kofoidii, and Pfiesteria piscicida and the naked ciliate Strombidium sp. were able to feed on A. granifera. With increasing mean prey concentrations, the growth and ingestion rates of G. dominans feeding on A. granifera rapidly increased and became saturated or slowly increased. The maximum growth and ingestion rates of G. dominans on A. granifera were 0.305 d^-1 and 0.42 ng C predator^-1 d^-1 (3.8 cells predator^-1 d^-1), respectively. Furthermore, the growth and ingestion rates of O. marina on A. granifera at 1,700 ng C mL^-1 (15,454 cells mL^-1) were 0.037 d^-1 and 0.19 ng C predator^-1 d^-1 (1.7 cells predator^-1 d^-1), respectively. The growth and ingestion rates of G. dominans and O. marina feeding on A. granifera were almost the lowest among those on the dinoflagellate prey species. Therefore, G. dominans and O. marina may prefer A. granifera less than other dinoflagellate prey species. The low mortality rate of A. granifera may positively affect its bloom formation.