• Korean Journal of Soil Science and Fertilizer
• /
• v.49 no.1
• /
• pp.44-52
• /
• 2016

Plants response to phosphate starvation include the changes of activity of some enzymes, such as phosphatases, fructose-1,6-bisphosphatase, sucrose-phosphate synthase and nitrate reductase. In this study, to determine the effects of phosphate starvation on the change of activities of acid and alkaline phosphatase, fructose-1,6-bisphosphatase, sucrose-phosphate synthase, and nitrate reductase were studied in melon seedlings (Cucumis melo L.). The content of the protein and chlorophyll tended to relatively reduced in melon seedlings subjected to phosphate starvation. Acid phosphatase activity in first and second leaves of melon seedlings was relatively higher than that of third and fourth leaves of seedlings in 14 days after phosphate starvation treatment, respectively. Active native-PAGE band patterns of acid phosphatase in melon leaves showed similar to activities of acid phosphatase, whereas alkaline phosphatase activity was different from the change in the activity of acid phosphatase. Inorganic phosphate content in melon seedlings leaves was constant. The changes of Fructose-1,6-bisphosphatase and sucrose phosphate synthase activities showed similar patterns in melon seedlings leaves, and between these enzymes activities and phosphate nutrition negatively related. Fructose-1,6- bisphosphatase and sucrose phosphate synthase activities showed significant difference in second and fourth leaves, but nitrate reductase showed significant difference in first and second leaves in 14days after phosphate starvation treatment. We concluded that phosphate nutrition could affect the distribution of phosphate, carbon and nitrogen in melon seedlings.

• Journal of Korean Society on Water Environment
• /
• v.22 no.1
• /
• pp.23-29
• /
• 2006

Biosorption technology was used to remove hazardous materials from wastewater, herbicide, heavy metals, and radioactive compounds, based on binding capacities of various biological materials. Biosorption process can be explained by two steps; the first step is that target contaminants is in contact with microorganisms and the second is that the adsorbed target contaminants is infiltrated with inner cell through metabolically mediated or physico-chemical pathways of uptake. Until recently, no information is available to explain the definitive mechanism of biosorption. The purpose of this study is to evaluate biosorption capabilities of organic matters using activated sludge and to investigate affecting factors upon biosorption. Over 49% of organic matter could be removed by positive biosorption reaction under anoxic condition within 10 minutes. The biosorption capacities were constant at around 50 mg-COD/mg-MLSS for all batch experiments. As starvation time increased under aerobic or anaerobic conditions, biosorption capacity increased since higher stressed microorganisms by starvation was more brisk. Starvation stress of microorganisms was higher at aerobic condition than anaerobic one. As temperature increased or easily biodegradable carbon sources were used, biosorption capacities increased. Consequently, biosorption can be estimated by biological -adsorbed capability of the bacterial cell-wall and we can achieve the cost-effective and non -residual denitrification with applying biosorption to the bio-reduction of nitrate.

• Proceedings of the Zoological Society Korea Conference
• /
• 1998.10b
• /
• pp.309-309
• /
• 1998

No Abstract, See Full Text

• Journal of Microbiology and Biotechnology
• /
• v.21 no.2
• /
• pp.136-146
• /
• 2011

This study provides first-hand proteomic data on the survival strategy of Anabaena sp. PCC 7120 when subjected to long-term iron-starvation conditions. 2D-gel electrophoresis followed by MALDI-TOF/MS analysis of iron-deficient Anabaena revealed significant and reproducible alterations in ten proteins, of which six are associated with photosynthesis and respiration, three with the antioxidative defense system, and the last, hypothetical protein all1861, conceivably connected with iron homeostasis. Iron-starved Anabaena registered a reduction in growth, photosynthetic pigments, PSI, PSII, whole-chain electron transport, carbon and nitrogen fixation, and ATP and NADPH content. The kinetics of hypothetical protein all1861 expression, with no change in expression until day 3, maximum expression on the $7^{th}$ day, and a decline in expression from the $15^{th}$ day onward, coupled with in silico analysis, suggested its role in iron sequestration and homeostasis. Interestingly, the up-regulated FBP-aldolase, Mn/Fe-SOD, and all1861 all appear to assist the survival of Anabeana subjected to iron-starvation conditions. Furthermore, the $N_2$-fixation capabilities of the iron-starved Anabaena encourage us to recommend its application as a biofertilizer, particularly in iron-limited paddy soils.

• Proceedings of the Korean Society of Applied Pharmacology
• /
• 1992.05a
• /
• pp.54-54
• /
• 1992

약물, hormone, 독성물질등의 대사능과 발암 가능성등이 간장 장해시 및 ketosis시에 달라지는 원인과 기전, 독성물질 대사효소의 변동과 그 작용기전을 규명하고자, 대표적인 간장장해 물질인 carbon tetrachloride를 rat에 투여하여 간장 장해를 일으키고, 당뇨병, starvation, high-fat diet처리하여 ketosls상태를 만든 후에, specific cytochrome P45O polyclonal antibodies와 cDNA probes를 사용하여, enzyme activitieg, Western immunoblot analysis와 mRNA Northern blot analysis 등을 실험하여, 간장 장해와 ketosis시 cytochrome P45O의 변동과 그 작용기전, regulation을 규명하고자 하였다. 실험 결과, $CCl_4$투여후 P450IIE enzyme (aniline hydroxylase) 활성이 시간 의존적으로 급격히 떨어졌고, P450IIE protein양이 똑같은 방식으로 감소되었으나 mRNA level은 변화가 없었다. $CCl_4$에 의해서 P450IIE는 protein의 특이적인 파괴에 의한 post-translational reduction됨을 알 수 있었다. 반면에 당뇨병, starvation, high-fat diet등 ketosis시에는 P450IIE 효소활성이 2-3배 증가되었고, P450IIE protein양도 같은 수준으로 증가되었으며, mRNA도 증가 되었다. Ketosis시에는 P450IIE가 pretranslational activation됨을 알 수 있었다.

• Journal of Microbiology and Biotechnology
• /
• v.17 no.2
• /
• pp.305-312
• /
• 2007

This study focused on the involvement of the unusual nucleotide (p)ppGpp, a stringent factor, during the morphological and physiological differentiation of Streptomyces coelicolor. Two genes, relA and rshA, were disrupted to demonstrate the roles of the stringent factor in the differentiation. The intracellular concentration of (p)ppGpp in the wild-type (M600) and disrupted mutants was measured in relation to the intentional starvation of a specific nutrient, such as carbon, nitrogen, and phosphate or the in situ depletion of nutrients in a batch culture. As a result, it was found that the morphological characteristic of the ${\Delta}relA$ mutant was a bld phenotype forming condensed mycelia, whereas the ${\Delta}rshA$ mutant grew fast-forming spores and straightforward mycelia. In both mutants, the production of actinorhodin (Act) was completely abolished, yet the undecylprodigiosin (Red) production was increased. Intracellular (p)ppGpp was detected in the ${\Delta}relA$ mutant in the case of limited phosphate, yet not with limited carbon or nitrogen sources. In contrast, (p)ppGpp was produced in the ${\Delta}rshA$ mutant under limited carbon and nitrogen conditions. Therefore, (p)ppGpp in S. coelicolor was found to be selectively regulated by either the RelA or RshA protein, which was differentially expressed in response to the specific nutrient limitation. These results were also supported by the in situ ppGpp production during a batch culture. Furthermore, it is suggested that RelA and RshA are bifunctional proteins that possess the ability to both synthesize and hydrolyze (p)ppGpp.

• Journal of Microbiology and Biotechnology
• /
• v.17 no.12
• /
• pp.1949-1954
• /
• 2007

A simple way to prevent protein hyperglycosylation in Hansenula polymorpha was found. When glucose oxidase from Aspergillus niger and carboxymethyl cellulase from Bacillus subtilis were expressed under the control of an inducible methanol oxidase (MOX) promoter using methanol as a carbon source, hyperglycosylated forms occurred. In contrast, MOX-repressing carbon sources (e.g., glucose, sorbitol, and glycerol) greatly reduced the extent of hyperglycosylation. Carbon source starvation of the cells also reduced the level of glycosylation, which was reversed to hyperglycosylation by the resumption of cell growth. It was concluded that the proteins expressed under actively growing conditions are produced as hyperglycosylated forms, whereas those under slow or nongrowing conditions are as short-glycosylated forms. The prevention of hyperglycosylation in the Hansenula polymorpha expression system constitutes an additional advantage over the traditional Saccharomyces cerevisiae system in recombinant production of glycosylated proteins.

• Journal of Microbiology
• /
• v.45 no.4
• /
• pp.311-317
• /
• 2007

In this study, the effects of phosphate concentration and carbon source on the patterns of alkaline phosphatase (APase) and phospholipase (PLase) expression in Vibrio vulnificus ATCC 29307 were assessed under various conditions. The activities of these enzymes were repressed by excess phosphate (4 mM) in the culture medium, but this repression was reversed upon the onset of phosphate starvation in low phosphate defined medium (LPDM) containing 0.2 mM of phosphate at approximately the end of the exponential growth phase. The expressions of the two enzymes were also influenced by different carbon sources, including glucose, fructose, maltose, glycerol, and sodium acetate at different levels. The APase activity was derepressed most profoundly in LPDM containing fructose as a sole carbon source. However, the repression/derepression of the enzyme by phosphate was not observed in media containing glycerol or sodium acetate. In LPDM-glycerol or sodium acetate, the growth rate was quite low. The highest levels of PLase activity were detected in LPDM-sodium acetate, followed by LPDM-fructose. PLase was not fully repressed by high phosphate concentrations when sodium acetate was utilized as the sole carbon source. These results showed that multiple regulatory systems, including the phosphate regulon, may perform a function in the expression of both or either APase and PLC, in the broader context of the survival of V. vulnificus.

• ALGAE
• /
• v.32 no.2
• /
• pp.161-170
• /
• 2017

Fourier Transform Infrared (FTIR) spectroscopy was used to study carbon allocation patterns in response to N-starvation in the nearly ubiquitous diatom Chaetoceros muellerii. The role of gene expression, protein synthesis and transamination on the organic composition of cells was tested by using specific inhibitors. The results show that inhibition of key processes in algal metabolism influence the macromolecular composition of cells and and prior cell nutritional state can influence a cell's response to changing nutrient availability. The allocation of C can thus lead to different organic composition depending on the nutritional context, with obvious repercussions for the trophic web. This also shows that C allocation in algal cells is highly flexible and that C (and the energy associated with its allocation) can be variably and rapidly partitioned in algal cells in response to relatively short term perturbations. Furthermore, the data confirm and extend the utility of infrared spectroscopy as a probe of the metabolic state of autotrophic cells.

• Journal of Microbiology and Biotechnology
• /
• v.28 no.2
• /
• pp.267-274
• /
• 2018

Lipids in microalgae are energy-rich compounds and considered as an attractive feedstock for biodiesel production. To redirect carbon flux from competing pathways to the fatty acid synthesis pathway of Tetraselmis sp., we used three types of chemical inhibitors that can block the starch synthesis pathway or photorespiration, under nitrogen-sufficient and nitrogen-deficient conditions. The starch synthesis pathway in chloroplasts and the cytosol can be inhibited by 3-(3,4-dichlorophenyl)-1,1-dimethylurea and 1,2-cyclohexane diamine tetraacetic acid (CDTA), respectively. Degradation of glycine into ammonia during photorespiration was blocked by aminooxyacetate (AOA) to maintain biomass concentration. Inhibition of starch synthesis pathways in the cytosol by CDTA increased fatty acid productivity by 27% under nitrogen deficiency, whereas the blocking of photorespiration in mitochondria by AOA was increased by 35% under nitrogen-sufficient conditions. The results of this study indicate that blocking starch or photorespiration pathways may redirect the carbon flux to fatty acid synthesis.