• Journal of Microbiology and Biotechnology
• /
• v.16 no.6
• /
• pp.821-831
• /
• 2006

Unicellular green algae of the genus Haematococcus have been studied extensively as model organisms for secondary carotenoid accumulation. Upon environmental stress, such as strong irradiance or nitrogen deficiency, unicellular green algae of the genus Haematococcus accumulate secondary carotenoids in vesicles in the cytosol. Because secondary carotenoid accumulation occurs only upon specific environmental stimuli, there is speculation about the regulation of the biosynthetic pathway specific for secondary carotenogenesis. Because the carotenoid biosynthesis pathway is located both in the chloroplast and the cytosol, communication between both cellular compartments must be considered. Recently, the induction and regulation of astaxanthin biosynthesis in microalgae received considerable attention because of the increasing use of this secondary carotenoid as a source of pigmentation for fish aquaculture, as a component in cancer prevention, and as a free-radical quencher. This review summarizes the biosynthesis and regulation of the pathway, as well as the biotechnology of astaxanthin production in Haematococcus.

• 한국생물공학회:학술대회논문집
• /
• 2000.11a
• /
• pp.309-312
• /
• 2000

A halophilic bacterium was isolated from domestic marine. The bacterium was gram negative and motile. Transmission electron micrograph after cultivating for 6-, 20-, 72-, and 144 hrs showed that it was bacilli and contained intracellular granules, which were pleomorphic, larger in density by the time and considered to be PHB since they were positive on the sudan black B staining. The presence of sodium chloride was critical, because the isolated marine bacterium could not multiply and even produce any immunostimulant in the deficiency of sodium chloride. The strain produced an immunostimulant, which was investigated for the biological characteristics. The optimal conditions for the production of the immunostimulant were 1 % dextrose and 1 % yeast extract in artificial sea water for carbon and nitrogen sources, respectively. The initial pH and growth temperature for the production were 8.0 and $30^{\circ}C$ under the presence of oxigen, respectively.

• Clinical and Experimental Pediatrics
• /
• v.58 no.3
• /
• pp.77-83
• /
• 2015

Relative to a fetus of the same gestational age, very low birth weight (VLBW) infants are more likely to be underfed and to undergo growth restriction during their early hospital stay. The current trend towards "early and aggressive" nutritional strategies in VLBW infants aims to overcome the early nutritional deficiency and thereby boost postnatal catch-up growth, simultaneously improving long-term neurodevelopmental outcomes. Although the minimum starting amino acid (AA) dose to prevent negative nitrogen balance is well established, the upper limit and the rate of increase of early AA doses are controversial. Most randomized controlled trials show that early and high-dose (target, 3.5 to 4.9 g/kg/day) AA regimens, with or without high nonprotein calories, do not improve long-term growth and neurodevelopment. High-dose AA supplementation may lead to early metabolic disturbances and excessive or disproportionate plasma AA levels, particularly in infants of very low gestational age. Further large studies are needed to clarify the optimal strategy for early administration of parenteral AA doses in VLBW infants.

• Korean Journal of Microbiology
• /
• v.5 no.1
• /
• pp.20-23
• /
• 1967

I studied about temperature and pH concentration having influence upon chlorophyll decrease on the Glucose culture of Chlorella variegata Beijerinck(211/10a). I cultured under $25^{\circ}C$(standard), $15^{\circ}C$ and $35^{\circ}C$ and compared with each other. The culture of $15^{\circ}C$ didn't have any large difference with the standard culture($25^{\circ}C$) but the culture of $35^{\circ}C$ had a large amount of chlorophyll decrease without carbohydrate accumulation, stimulation of cell division and nitrogen-deficiency. Chlorella variegata had optimum pH 6.5-7 and was a little weak in all phenomenon under pH 8 rather than under pH 6.5-7. Under pH 5 they had deep chlorophyll decrease without phephytin.

• Applied Biological Chemistry
• /
• v.5
• /
• pp.49-51
• /
• 1964

Results obtained from Leaves and soils may be summarized as follow; It was found that the rice plant which grown under the deficiency of silica, manganese and magnesium become very susceptible to Helminthosporium leaf spot, as compared with that grown under normal condition. While no close correlation was found in nitrogen, phosporus and potassium between the health and disease. On the other hand, reducible manganese content of normal paddy soils is also 13.2 times as high as that of diseased paddy soils (Akioch soil) Considering from the results, it seems to have certain relationship between resistance to Helminthosporium and unbalance of inorganic elements in rice blade.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.16 no.5
• /
• pp.431-443
• /
• 2014

In this paper case studies of artificial ground freezing, which have not been applied in Korea, have been investigated for the water cut-off in a subsea tunnel under high water pressure and the most commonly used cooling mediums of brine and liquid nitrogen are examined. Since sea water with pressure has the lower freezing point than pure water, the lower temperature cooling medium is required in the application of subsea tunnel. Also, the cooling medium must have refrigeration safety and is able to reduce executing time. Brine freezing system can reuse cooling medium and is safer than liquid nitrogen freezing. But it takes more time to freeze ground and needs complex circulation plants. On the other hand, liquid nitrogen freezing system can't recycle cooling medium and may cause breathing problems or asphyxiation through oxygen deficiency. But, freezing with liquid nitrogen is fast and requires simple refrigeration equipment. Principal elements of design for ground freezing in subsea tunnel have been extracted and these elements are needed further research.

• Korean Journal of Soil Science and Fertilizer
• /
• v.19 no.1
• /
• pp.56-62
• /
• 1986

Fertilization response on production and quality of flue-cured tobacco as to different level of nitrogen, phosphorus, and potassium were studied in a field experiment. The results were summarized as follows: 1. Growth and yield of flue-cured tobacco were significantly better in higher nitrogen fertilization levels, regardless of soil fertility, but the negative correlation was recognized between the quality of leaves and the amounts of nitrogen application. While, both fertilizers of phosphorous and potassium did not have should little effect on the tobacco yield and quality. 2. The optimum ratio of N, P, and K fertilizer applications were decided by the appearance of the proper yield and the best quality of tobacco leaves. The proportion of N:P:K was 2:1:4. 3. The single effect (Complete plot minus Non-fertilized plot) of N, P, and K on yield and quality of cured leaf was greatly affected by nitrogen, but the combined effect (Nutrient deficiency plot minus Non-fertilzier plot) of that were only slightly affected by P and K.

• Korean Journal of Soil Science and Fertilizer
• /
• v.31 no.4
• /
• pp.324-329
• /
• 1998

To investigate the changes of $NH_4-N$ in soil, nitrogen uptake by rice plant, nitrogen use efficiency and rice yield by the application of Latex Coated Urea(LCU) on direct seeding rice, rice was planted on paddy field, Jeonbuk series at the Honam area, from 1996 to 1997. Nitrogen in LCU applied as basal dressing in whole layer was dissolved almost untill non-productive stage. Thus, nitrogen deficiency symptom appeared and N in shoot was 1.75% showing 28.1 of SPAD value at heading stage. However percentage recovery of fertilizer N was higher in LCU than with urea application. Top dressing of urea at panicle initiation stage in addition to basal dressing of LCU, increased rice yield by 9%. Conventional split application of urea on the surface decreased the percentage recovery of fertilizer N to 56.9% of whole layer application plot.

• Korean Journal of Soil Science and Fertilizer
• /
• v.45 no.6
• /
• pp.910-919
• /
• 2012

The role of inorganic nitrogen assimilation in the production of amino acids, organic acids and soluble sugars is one of the most important biochemical processes in plants, and, in order to achieve normally, nitrate uptake and assimilation is essential. For this reason, the characterization of nitrate assimilation and metabolite composition from leaves, roots and xylem sap of tomato (Solanum lycopersicum) was investigated under different nitrate levels in media. Tomato plants were grown hydroponically in liquid culture under five different nitrate regimes: deficient (0.25 and 0.75 mM $NO_3{^-}$), normal (2.5 mM $NO_3{^-}$) and excessive (5.0 and 10.0 mM $NO_3{^-}$). All samples, leaves, roots and xylem sap, were collected after 7 and 14 days after treatment. The levels of amino acids, soluble sugars and organic acids were significantly decreased by N-deficiency whereas, interestingly, they remained higher in xylem sap as compared with N-normal and -surplus. The N-excessive condition did not exert any significant changes in metabolites composition, and thus their levels were similar with N-normal. The gene expression and enzyme activity of nitrate reductase (NR), nitrite reductase (NIR) and glutamine synthetase (GS) were greatly influenced by nitrate. The data presented here suggest that metabolites, as a signal messenger, existed in xylem sap seem to play a crucial role to acquire nitrate, and, in addition, an increase in ${\alpha}$-ketoglutarate pathway-derived amino acids under N-deficiency may help to better understand plant C/N metabolism.

• KSBB Journal
• /
• v.9 no.5
• /
• pp.475-482
• /
• 1994

To find out the optimum conditions for the cell growth and the synthesis of PHB in A. eutrophus, the effects of culture conditions and extracellular by-products were investigated. Glucose and$>(NH_4)_2HP0_4$were optimum carbon and nitrogen sources, respectively for cell growth of A. eutrophus. PHB accumulation was stimulated by deficiency of nutrients such as $>NH_4^{3-}, P0_4^{3-}, and Mg^{2+}$ in the medium. $>NH_4^+$, deficiency was the most suitable for PHB accumulation and PHB accumulation ratio was reached 42% of dry cell weight. The specific growth rate was increased 1.5 times by addition yeast extract in the medium, and proteins and vitamins are supposed a main factor of that effect. The extracellular products such as ethanol and butanediol were excreted under anaerobic conditions. And ethanol was found to decrease the specific growth rate.