• KSBB Journal
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• v.13 no.2
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• pp.187-194
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• 1998

For mass production of polyhydroxyalkanoates (PHA), high cell density cultures of Alcaligenes eutrophus by fed-batch culture under phosphate-limitation condition has been investigated. PHA accumulation by the regulation by the regulation of initial phosphate concentration could be automatically induced, and high density cell culture above 200 g/L also could be successfully produced. The production of Poly-$\beta$-hydroxybutyrate (PHB) and dry cell weight increased with increasing the initial phosphate concentration. When the initial concentrations of phosphate were in the ranges of 1.5~4.5 g-PO$_4$/L, PHB and dry cell weight obtained were 83~266 g/L and 61~216 g/L, respectively, and PHB productivity was in the ranges of 1.35~3.10 g/L.h. When a mixture of glucose and propionic acid is used as carbon sources, poly(3-hydroxybutyrate-co-poly-3-hydroxyvalerate), P(3HB-co-3HV), could be also successfully produced under phosphate limitation condition. When the mole ratio of propionic acid to glucose in the feeding solution is 0.22, a final dry cell weight of 150 g/L and a P(3-HB-co-3HV) of 90 g/L were produced. Morphological changes and size distribution of PHB granules synthesized in A. eutrophus under phosphate-limitation condition are determined by TEM during the course of fed-batch. Mean granule diameters of PHB produced are in the range of 0.36~0.39 $\mu$m, and mean cell size was elongated from 0.54~0.59 $\mu$m$\times$ 1.3~1.5 $\mu$m to 0.83~0.89 $\mu$m $\times$2.0~2.3 $\mu$m. Phosphate concentration in media did not affect size distribution of PHB granule and cell.

• Journal of Microbiology and Biotechnology
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• v.9 no.6
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• pp.751-756
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• 1999

For mass production of poly(3-hydroxybutyrate) (PHB), high cell density cultures of Ralstonia eutropha were carried out in 2.5-1 and 60-1 fermentors by two fed-batch culture techniques of nitrogen and phosphate limitation. When the nitrogen limitation technique was employed using both an on-line glucose monitoring and control system, a high concentration level of PHB (121g/l) was obtained in the small-scale fermentor of 2.5 1. However, the PHB concentration obtained in a large-scale fermentor of 60 1 only turned out to be 60g/l. In contrast, when another fed-batch culture technique of the phosphate-limitation employing dissolved oxygen (DO) stat glucose feeding was used, a large amount of PHB was successfully produced in both 60-1 and 2.5-1 fermentors. In a 2.5-1 fermentor, concentrations of PHB and cells obtained in 58 h were 175 and 210 g/l, respectively, which corresponded to the PHB productivity level of 3.02 g/l/h. In a 60-1 fermentor, a final cell concentration of 221 g/l and a PHB concentration of 180 g/l with PHB productivity level of 3.75 g/l/h were obtained in 48h. PHB content and yield from glucose were 81% and 0.38g PHB/g glucose, respectively. These data suggest that the phosphate limitation technique is more effective compared to nitrogen limitation in the mass production of PHB by R. eutropha of a large scale.

• BMB Reports
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• v.40 no.5
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• pp.708-714
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• 2007

The two-component signal transduction, which typically consists of a histidine kinase and a response regulator, is used by bacterial cells to sense changes in their environment. Previously, the SphS-SphR histidine kinase and response regulator pair of phosphate sensing signal transduction has been identified in Synechocystis sp. PCC 6803. In addition, some response regulators in bacteria have been shown to be cross regulated by low molecular weight phosphorylated compounds in the absence of the cognate histidine kinase. The ability of an endogenous acetyl phosphate to phosphorylate the response regulator, SphR in the absence of the cognate histidine kinase, SphS was therefore tested in Synechocystis sp. PCC 6803. The mutant lacking functional SphS and acetate kinase showed no detectable alkaline phosphatase activity under phosphate-limiting growth conditions. The results suggested that the endogenous acetyl phosphate accumulated inside the mutants could not activate the SphR via phosphorylation. On the other hand, exogenous acetyl phosphate could allow the mutant lacking functional acetate kinase and phosphotransacetylase to grow under phosphate-limiting conditions suggesting the role of acetyl phosphate as an energy source. Reverse transcription PCR demonstrated that the transcripts of acetate kinase and phospho-transacetylase genes in Synechocystis sp. PCC 6803 is up-regulated in response to phosphate limitation suggesting the importance of these two enzymes for energy metabolism in Synechocystis cells

• Korean Journal of Microbiology
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• v.38 no.4
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• pp.318-321
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• 2002

To induce recombinant protein under phosphate restricted conditions such as soil, we have constructed the expression vector (pEAAP) with phoA gene promoter of Enterobacter aerogenes. To construct the pEAAP, deletion of the T7 promoter and lac operator from pET-22b(+) by BglII-XhoI digestion and addition of the phoA gene promoter (containing the pho box) were performed. To test pEAAP as an expression vector controled by phosphate limitation, pEAPHY1 was constructed with the phytate gene (Bsa-phy1) of Bacillus subtillis var. amyloliquefaciens (KCTC 8913P). Under the phosphate-limitation condition, CK-PHY1 ( Escherichia coli JM109 was transformed with pEAPHY1) expressed the 41 kD Bsa-Phy1 . Also CK-PHY1 formed the clear zone in solid medium containing phytate as a sole phosphate source.

• KSBB Journal
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• v.5 no.1
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• pp.9-17
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• 1990

The growth and fermentation profiles of Clostridium acetobutylicum KCTC 1037 were examined in batch and continuous modes with pH variation and phosphate limitation. Clostridium acetobutylicum KCTC 10 37 grew better at pH 4.5 than at pH 5.5 or 6.5. Acetate and butyrate were produced at pH 5.5, whereas culture at pH 4.5 produced acetone and butanol. Solvent production was increased by the phosphate limitation in a batch culture, but in a phosphate-limited continuous culture for 400 hours steady-state solventogenesis was not observed. The induction and maintenance of solventogenesis presumably require not only acidic condition or phosphate limitation but also favourable bioenergetic condition.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.346-349
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• 2000

In order to investigate the characteristics for RNA accumulation, continuous cultures of S. cerevisiae MTY62 under the carbon-limitation or carbon-phosphate-limitation were performed. In the carbon-limited chemostat, the highest RNA content of 144 mg-RNA/g-dry cell was observed at the dilution rate of $0.30\;hr^{-1}$. In the carbon and phosphate-limited chemostat, the culture condition with the dilution rate of $0.25\;hr^{-1}$ gave the maximal RNA content of 209 mg-RNA/g-dry cell. The accumulation rate of RNA $(mg-RNA/L\;{\cdot}\;hr)$ was decreased at higher dilution rate in the carbon and phosphate-limited chemostat.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.2
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• pp.181-189
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• 2008

Phosphate is the limiting factor leading to the eutrophication in nature and has been usually removed by the luxury uptake of PAOs(Phosphate accumulating organisms). The purpose of this study was the control of wastewater treatment removing phosphorus. The control of wastewater treatment process was performed by optimal and adaptive control. They were performed as followings. Firstly the inflow phosphate concentration was measured and the optimal aeration time was calculated by simplified ASM No. 2 for the phosphate to be 1.0 mg/L in effluent. It was optimal control. But when the phosphate concentration in effluent was not 1.0 mg/L, adaptive control was necessary to coincide the objective of control with real value. Then it was performed as the objective phosphate concentration in effluent was changed according to calculation of errors and it was adaptive control. The wastewater treatment process had been controlled by them for about one month. The range of phosphate concentration in effluent 0.2$\sim$3.2 mg/L and the average of it was 1.0 mg/L. The limitation of luxury uptake occurred two times while wastewater treatment process was running. After the analysis of laboratory tests, we knew the reasons were the shortage of ammonia nitrogen and the excessive aeration.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 1986.12a
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• pp.509.2-509
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• 1986

Owing to the growing interest in the production of fuels and chemicals from biomass the well-know butanol-acetone fermentation as carried out by Clostridium acetobutylicum has been intensely studied again in recent years. Several solvent-yielding fermentation processes were established which are operated by using batch cultures or continuous cultures. 1 could be shown that under conditions of phosphate limitation an asporogenous mutant of C. acetobutylicum establishes itself in a chemostat which produces the solvents continuously. Attempts have been made to change the butanol/acetone ratio in favor of butanol production. A corresponding shift of the product spectrum can be achieved by carbon monoxide addition to the head space of the fermentation (B.H. Kim et al., App. Envioron. Microbiol. 48, 764-770 1984) or by iron limitation. Progress has been made in understanding the mechanism underlying the shift from acid to solvent prodcction. Experimental results are in agreement with the view that intracellular accumulation of acetic and butyric acid results in a shortage of phosphate and coenzyme A. This shortage may serve then as signal for the synthesis of the enzymes involved in the formation of acetone and butanol.

• Microbiology and Biotechnology Letters
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• v.35 no.4
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• pp.272-277
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• 2007

The physiological responses of microorganisms to specific nutrient limitation can be regulated at the transcriptional levels. In this study, in order to develop the Pichia pastoris-derived promoter inducible by nutrient-limited condition, we constructed cDNA libraries using RT-PCR of total RNA from P. pastoris in steady-states of phosphate-limited chemostat with different dilution rates. Various genes were detected from cDNA library. Among these genes, the gene encoding putative sodium/phosphate ($Na^+$/Pi) symporter (NPS), high affinity transporter of phosphate, was detected. It was observed that expression of NPS increased in a manner specific to phosphate-limited condition through Northern blot. Therefore, it is thought that the promoter from NPS gene may have the potential as auto-inducible promoter by phosphate-limited culture condition without inducer.

• Ocean and Polar Research
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• v.32 no.2
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• pp.97-111
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• 2010

Phytoplankton production is affected by various physico-chemical factors of environment. However, one of the most critical factors generally accepted as controlling primary production of phytoplankton is nutrients. It has recently been found that the succession of phytoplankton groups and species are closely related to the chemical properties of ambient water including nutrient limitation and their ratios. In Jangmok Bay, silicate and nitrate are primarily supplied by rainfall, while phosphate and ammonia are supplied by wind stress. Typhoons are associated with rainfall and strong wind stress, and when typhoons pass through the South Sea, such events may induce phytoplankton blooms. When nutrients were supplied by heavy rainfalls during the rainy season and by summer typhoons in Jangmok Bay, the dominant taxa among the phytoplankton groups were found to change successively with time. The dominant taxon was changed from diatoms to flagellates immediately after the episodic seasonal events, but returned to diatoms within 3~10 days. Pseudo-nitzschia spp. were dominant mainly in the presence of low phosphate levels during the first of the survey which included the rainy season, while Skeletonema costatum was dominant when phosphate concentrations were high due to the strong wind stress during the latter half of the survey as a result of the typhoon. The competition between S. costatum and Chaetoceros spp. appeared to be regulated by the silicate concentration. S. costatum preferred high silicate and phosphate concentrations; however, Chaetoceros spp. were able to endure low silicate concentrations. These results implied that, in coastal ecosystems, the input patterns of each nutrient supplied by rainfall and/or wind stress appeared to contribute to the summer succession of phytoplankton groups and species.