• Journal of Microbiology and Biotechnology
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• v.28 no.12
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• pp.2019-2028
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• 2018

Natural astaxanthin mainly derives from a microalgae producer, Haematococcus pluvialis. The induction of nitrogen starvation and high light intensity is particularly significant for boosting astaxanthin production. However, the different responses to light intensity and nitrogen starvation needed to be analyzed for biomass growth and astaxanthin accumulation. The results showed that the highest level of astaxanthin production was achieved in nitrogen starvation, and was 1.64 times higher than the control group at 11 days. With regard to the optimization of light intensity utilization, it was at $200{\mu}mo/m^2/s$ under nitrogen starvation that the highest astaxanthin productivity per light intensity was achieved. In addition, both high light intensity and a nitrogen source had significant effects on multiple indicators. For example, high light intensity had a greater significant effect than a nitrogen source on biomass dry weight, astaxanthin yield and astaxanthin productivity; in contrast, nitrogen starvation was more beneficial for enhancing astaxanthin content per dry weight biomass. The data indicate that high light intensity synergizes with nitrogen starvation to stimulate the biosynthesis of astaxanthin.

• Journal of Microbiology and Biotechnology
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• v.24 no.9
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• pp.1207-1215
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• 2014

Candida albicans, the major human fungal pathogen, undergoes morphological transition from the budding yeast form to filamentous growth in response to nitrogen starvation. In this study, we identified a new function of GST2, whose expression was required for filamentous growth of C. albicans under nitrogen-limiting conditions. The Gst2p showed Gst activity and required response to oxidative stress. The ${\Delta}gst2$ mutant displayed predominantly yeast phase growth in low ammonium media. Such morphological defect of ${\Delta}gst2$ mutants was not rescued by overexpression of Mep2p, Cph1p, or Efg1p, but was rescued by either overexpression of a hyperactive $RAS1^{G13V}$ allele or through exogenous addition of cyclic AMP. In addition, the ${\Delta}gst2$ mutants had lower levels of RAS1 transcripts than wild-type cells under conditions of nitrogen starvation. These results were consistent with the Ras1-cAMP pathway as a possible downstream target of Gst2p. These findings suggest that Gst2p is a significant component of nitrogen starvation-induced filamentation in C. albicans.

• Plant Biotechnology Reports
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• v.5 no.4
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• pp.309-315
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• 2011

Rice grown in anaerobic waterlogged soil accumulates ammonium as a major source of nitrogen (N). We have compared the physiological symptoms of rice seedlings subjected to N-starvation stress with those receiving sufficient N, based on measurements of shoot/root length and weight and an analysis of protein expression patterns. N starvation marginally increased root growth but notably decreased shoot biomass. N uptake was reduced by >50% in the roots and shoots of N-starved seedlings. To better understand the mechanism of N starvation in rice, we performed a comparative proteome analysis of proteins isolated from rice leaves. Twenty-five differentially expressed proteins were analyzed by matrixassisted laser desorption/ionization time-of-flight (TOF) mass spectrometry and electron spray ionization quadrupole TOF. Functional analysis of the N-starvation response proteins suggested their involvement in protein synthesis and fate, metabolism, and defense. These results indicate that these proteins may play important roles in regulating the plant's complex adaptation responses for N use during N starvation. The proteins may be useful for further characterization of protein function in plant N nutrition.

• Journal of Bio-Environment Control
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• v.7 no.3
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• pp.253-258
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• 1998

Lettuce plants(Lactuca sativa var. capitata L.) were subjected to nitrogen starvation for 18, 14, 11, 7, and 0 days before harvest. The nitrate content of lettuce was decreased greatly by nitrogen starvation and also its fresh weight. The nitrate content of the middle part of leaves was lowest at the treatment of 18 days before harvest. In the inner part it was lowest at the treatment of 11 and 14 days before harvest. The longer the period of nitrogen starvation was, the more were decreased the absorption rates of cations at harvest. During the experiment, the pH was decreased except the treatment of 7 days before harvest. The EC was continuously increased regardless of treatments.

• Journal of Microbiology
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• v.43 no.1
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• pp.44-48
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• 2005

In our previous study, the first structural gene (GGTI) encoding ${\gamma}-glutamyl$ transpeptidase was cloned and characterized from the fission yeast Schizosaccharomyces pombe, and its transcription, using the GGTI-lacZ fusion gene, containing the 1,085 bp upstream region from the translational initiation point, was found to be enhanced by sodium nitroprusside and L-buthionine-(S,R)-sulfoximine (BSO). In the present work, regulation of the GGTI gene was further elucidated. Non-fermentable carbon sources, such as acetate and ethanol, markedly enhanced the synthesis of ${beta}-galactosidase$ from the GGTI-lacZ fusion gene. However, its induction by non-fermentable carbon sources appeared to be independent of the presence of the Pap1 protein. Nitrogen starvation also gave rise to induction of GGTI gene expression in a Pap1-independent manner. The three additional fusion plasmids, carrying 754, 421 and 156 bp regions, were constructed. The sequence responsible for the induction by non-fermentable carbon sources and nitrogen starvation was identified to exist within a -421 bp region of the GGTI gene. Taken together, the S. pombe GGTI gene is regulated by non-fermentable carbon sources and nitrogen starvation.

• Journal of Microbiology
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• v.37 no.3
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• pp.141-147
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• 1999

Thirteen transcriptionally-fused carbon starvation mutants, derived from Pseudomonas putida ATCC 12633, were analyzed for their survivability and transcriptional induction profiles upon carbon starvation. One of these mutants, MK114, which exhibited the lowest survivability and the highest induction rate, was selected and further examined under different starvation (nitrogen and phosphate) and stress (osmolarity, H2O2, salts, alcohol, and heat) conditions. Under all tested conditions MK114 induced ${\beta}$-galactosidase activity, implying that the interrupted gene (cst114) is a general starvation and stress response gene. The rate of induction ranged from 2.6-fold for phosphate starvation to 3.7-fold for osmotic shock. The mini-Tn5 flanking DNA was cloned from the chromosome of MK114. The cloned DNA fragment exhibited carbon starvation activity, indicating that this fragment contains a carbon starvation-related promoter region. This region was partially sequenced. Possible physiological roles of Cst114 in a carbon sensing mechanism and in other stress responses are also discussed.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.25 no.5
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• pp.371-382
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• 1992

Biochemical composition, the rates of nitrogen excretion in the form of ammonia, amino acids and total nitrogen, and oxygen consumption of the shrimp Crangon affinis were measured at three temperature regimes $(7,\;15,\;and\;25^{\circ}C)$ and the variations were also determined for starvation periods (1-25 days). The composition of the major biochemical fractions was analysed into carbohydrate: $4.2\%,\;protein:\;68.6\%,\;lipid:\;7.0\%,\;chitin:\;6.3\%,\;and\;ash:\;14.6\%,$ all expressed as percentage of dry weight. Molting frequency was lower at $7^{\circ}C\;than\;25^{\circ}C$ during the period of starvation, and during the same period the higher temperature was, body weight and body compositions the more decreased. Through all starvation periods $O_2$ consumption tended to decrease but total nitrogen tended to increase at any temperature regimes. The dominant form of excreted total nitrogen was ammonia-N at any temperature. From the O:N ratio it appeared that carbohydrate and lipid reserves were quickly exhausted (1-5 days), and that proteins were the substrates oxidized to meet the energetic requirements of C. affinis at any temperature. After 25 days of starvation the O:N ratio remained constant near a value of 8, which indicates that only proteins were being utilized at three temperatures. After 25 days of starvaion C. affinis excreted 23.01ug N/mg body nitrogen per day at $7^{\circ}C,\;32.97\mu g\;N/mg$ body nitrogen per day at $15^{\circ}C,\;and\;44.81\mu g\;N/mg$ body nitrogen per day at $25^{\circ}C$, and lost about 1.75, 2.47 and $3.29^{\circ}C$ of body protein per day at 7, 15, and $25^{\circ}C$ respectively.

• Korean Journal of Microbiology
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• v.54 no.4
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• pp.309-319
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• 2018

Previously, six Schizosaccharomyce pombe mutants that induce pheromone even in the presence of nitrogen source were isolated from a bank of temperature sensitive mutants. In this report, one of these mutants, pws6 was further characterized. The pheromone induction in pws6 mutant cells was specific to nutrient: the M-factor pheromone was induced without nitrogen starvation but not without glucose starvation. This result suggests that the pws6 mutant might have a specific defect in the pathway for nitrogen starvation. The pws6 mutant induces P-factor pheromone as well as M-factor without starvation of nitrogen in temperature sensitive mode, suggesting that the pheromone induction phenotype of pws6 mutation is not cell-type specific. From cloning of the $pws6^+$ gene by complementation of the temperature sensitive growth defect, three plasmids containing 8.1 kb, 3.3 kb, and 4.8 kb yeast DNA were recovered. These plasmids complement the growth defect of the pws6 mutant by 100%, 70%, and 10~20%, respectively. The abilities of these plasmids to complement pheromone induction phenotype of pws6 mutant cells were correlated well with the efficiencies of complementation of the growth defect. With comparison of their open reading frames to the complementation efficiencies, it is concluded that the open reading frame, SPBC19C7.06 is responsible for the complementation of temperature sensitive phenotype of the pws6 mutant. This open reading frame, named prs1, contains one long exon with no intron and encodes a putative prolyl tRNA synthetase. The putative Prs1 protein exhibits significant similarities to the prolyl tRNA synthetases of other species.

• Journal of Marine Bioscience and Biotechnology
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• v.11 no.2
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• pp.81-88
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• 2019

In this study, effects of nitrogen (N) and phosphorus (P) starvation on the cell growth and fatty acid (FA) production of newly isolated freshwater microalgae were investigated. The microalgae were identified as Chlorella sp. and Parachlorella sp. through 18S rRNA sequencing. Optimal culture temperature and light intensity were investigated using a high-throughput photobioreator, and the result was validated in 0.5 L bubble column photobioreactors using BG-11 without NaNO₃ and/or K₂HPO₄. Under nutrient starvation conditions, total FA contents of the microalgae were significantly changed rather than FA composition. Starvation of both N and P was most effective for increasing FA contents in Parachlorella sp (24.4±0.1%) whereas highest FA contents (42.6±1.8%) was achieved when only P was starved in Chlorella sp. among tested conditions. These results suggest an effective strategy for increasing FA production from microalgae using appropriate nutrient starvation.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 2004.06a
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• pp.224-229
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• 2004