• Microbiology and Biotechnology Letters
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• v.28 no.6
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• pp.355-360
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• 2000

A UVmutant of Candida rugosa IF00750 was made and used to convert butYlic acid to D-$\beta$-hydroxybutyric acid(D-$\beta$-HBA). Major regulating factors for D-$\beta$-HBA fennentation were investigated via chemostat analyses. The maximum specific productivity was achieved at a specific growth rate of $0.06h^{-1}$ where the glucose and butyric acid concentrations in the fermentor were 10 g/L and 8.7 g/L. respectively. A fed-batch fennentation was performed with maintenance of the optimum glucose and butyric acid concentrations. The D-$\beta$-HBA concentration after 120 h of cultivation reached 12.4 g/L, which was 4.7 times greater illan the concentration obtained by batch fermentation.

• Microbiology and Biotechnology Letters
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• v.21 no.3
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• pp.221-228
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• 1993

In order to achieve poly-beta-hydroxybutyric acid (PHB) production using recombinant DNA in various host bacterial cells, the isolation of genes for PHB biosynthesis was attempted. As a result, a 5.2kb DNA fragment containing phbCAB operon of Alcaligenes eutrophus was isolated by colony hybridization using synthetic oligodeoxyribonucleotides as probes. The constructed recmbinant plasmid pSK(+)-phbCAB operon was transferred to Escherichia coli, and the obtained transformant accumulated considerable amount of PHB.

• Korean Chemical Engineering Research
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• v.54 no.5
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• pp.719-721
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• 2016

Formate has been considered as an environmentally sustainable feedstock that can be used to accelerate the production of valuable chemicals. This study presents brief results of the formatotrophic production of Poly-${\beta}$-hydroxybutyric acid (PHB) by Methylobacterium sp. To evaluate the production of PHB, five species of Methylobacteria were tested using formate as the sole carbon and energy source. Methylobacterium chloromethanicum CM4 exhibited the highest productivity of PHB, which showed 1.72 g/L PHB production, 32.4% PHB content, and 0.027 g-PHB/g-formate PHB yield. These results could be used for the formatotrophic production of PHB with the concurrent reduction of $CO_2$ to formate.

• Applied Biological Chemistry
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• v.34 no.3
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• pp.273-278
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• 1991

Methanol assimilating bacterium, Pseudomonas sp. ILS-003 was used to investigate the optimum conditions for the production of $poly-{\beta}-hydroxybutyric$ acid from methanol. For PHB production, the optimum initial pH was 6.4 and the optimum temperature was $30^{\circ}C$. Also the optimum methanol concentration was found to be 1.0%(v/v). In the PHB production, $(NH_4)_2SO_4$ was the most effective nitrogen source and the optimum concentration was 0.8 g/l, which was eqivalent to 17.4 in C/N ratio. Also, deficiency of the 2 valence metal ions in the medium had stimulating effect on PHB accumulation. Under the optimum substrate concentration, successive feeding of 0.25%(v/v) methanol was the most effective on PHB production. Under the optimum conditions, 1.94 g/l of PHB and 2.78 g/l of dry biomass were produced in 96 hours, and the yield was 69.8%(w/w).

• Microbiology and Biotechnology Letters
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• v.20 no.4
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• pp.363-370
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• 1992

Microorganisms capable of accumulating poly-p-hydroxybutyric acid(PHB) were isolated from soil by enrichment culture technique. Among them, the strain designated as FL-027 had high PHB productivity and was identified as Alcaligenes. The optimal medium composition for cell growth was 8.0 $g/\ell$ of fructose and 3.0 $g/\ell$ of $(NH_4)_2S0_4$, equivalent to C/N ratio 5.04 at pH 7.0 and $30^{\circ}C$. To investigate the optimal conditions for the PHB accumulation, we divided the process into two stages; the first stage for the growth of the cell in nutrient-rich medium and the second stage for the PHB accumulation in nutrient-deficiency medium. The optimal conditions for PHB accumulation were 8.0 $g/\ell$ of fructose and 0.25 $g/\ell$ of $(NH_4)_2S0_4$, equivalent to C/N ratio 60 at pH 6.5 and $30^{\circ}C$. PHB accumulation was stimulated by deficiency of nutrients such as $NH_4^+$, $Ca^{2+}$, $SO_4^{2+}$ in medium. Among them. $NH_4^+$ deficiency was chosen because of its effectiveness. We found the inhibition of cell growth by fructose in batch culture. In order to keep the fructose concentration at an optimal level, intermittent feeding fed-batch culture was employed, and the cell concentration as high as 10.83 $g/\ell$ whose PHB content was responsible for 43% of the dry cell weight. The purified PHB was identified as homopolymer of 3-hydroxybutyric acid by using IR and $^1H-NMR$.

• KSBB Journal
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• v.6 no.1
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• pp.79-83
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• 1991

Using PHB biopolymer as polymer matrix, the release mechanism of a model drug, silver sulfadiazine was studied. The release behavior actually conformed to the Higuchi's diffusion controlled model. The release rate was delayed with an increasing proportion of PHB, whereas decreased as glycerine concentration incresed. The release rate was increased as the polymer matrix thickness increased.

• KSBB Journal
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• v.11 no.2
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• pp.246-253
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• 1996

An obligatory methanotroph Methylosinus trichosporium OB3b was cultivated for the production of poly-${\beta}$-hydroxybutyric acid(PHB) in shake-flask using liquefied natural gas(LNG) as the sole source of carbon and energy. The maximal specific growth rate decreased by 40% using LNG compared with that obtained with pure methane. This is attributed to the inhibition by ethane and propane presents in the LNG as impurities. For the production of PHB, two-stage culture separating the production stage from the growth stage was carried out. PHB accumulation was observed after switching nutrient-sufficient to nutrient-limited condition of non-carboneous component (NO3-, PO43-, K+, Na+, Fe2+, or Mg2+). The limitation of K+ or Mg2+ resulted in relatively high PHB content, but the highest content was obtained by nitrate limitation. The optimal pH and temperature for PHB accumulation was 7.0 and $30^{\circ}C$. Under the optimal condition the maximal PHB content was about 45% after 4-day cultivation.

• Microbiology and Biotechnology Letters
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• v.18 no.3
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• pp.273-279
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• 1990

For poly- $\beta$ -hydroxybutyrate (PHB) production, a pink-pigmented facultative methylotrophic bacterium (PPFM) P-10 was newly isolated from soils through methanol-enrichment culture. The optimal medium composition for cell growth was 1.0% (vlv) of methanol as carbon source and l.Og/l of ,TEX>$NH_4Cl$, equivalent to C/N ratio of 13.2 at pH 7.0 and $30^{\circ}C$. To investigate the optimal condition for YHB accumulation, two-stage culture technique was adopted; first stage for cell growth and second stage for accumulation of PHB providing unbalanced growth conditions. The optimal PHB accumulation was 1.0% (vIv) of methanol and 0.26gll of $NH_4Cl$, C/N of 50.8 at pH 6.0. To overcome methanol inhibition on cell growth, intermittent feeding fed-batch culture technique was employed, and the cell concentration as high as 14gll with 40% of PHB was achieved. The purified PHB was identified using IR and $1^H NMR$ as homopolymer of 8hydroxybutyric acid. The absorption spectrum of extracted pink colored microbial pigment was alsa investigated.

• Journal of Microbiology and Biotechnology
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• v.7 no.5
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• pp.360-362
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• 1997

A transposon Tn5 mutant of Rhodobacter sphaeroides 2.4.1 was isolated for its impaired ability of growth on minimal medium containing ${\beta}$-hydroxybutyric acid as a sole carbon source. The mutant, R. sphaeroides S7 showed approximately 6-fold decrease in ${\beta}$-hydroxybutyrate dehydrogenase activity compared with that of wild type. In R. sphaeroides S7 the Tn5 was located in DNA region corresponding to a 4.2-kb EcoRI DNA fragment of R. sphaeroides 2.4.1 chromosome.

• Analytical Science and Technology
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• v.36 no.4
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• pp.170-179
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• 2023

Starvation, diabetes, alcoholism and hypothermia cause ketoacidosis in the human body; therefore, the cause of death can be determined by analyzing ketone bodies in the blood of the deceased. In the case of decomposition of the cadaver, however, since collecting intact blood is impossible, ketone body analysis is performed using the spleen. However, the index for diagnosing ketoacidosis is based on blood concentration, and its correlation with ketone bodies present in the spleen remains unknown. In particular, since decomposition proceeds rapidly during summer, when temperature and humidity are high, understanding the correlation between ketone bodies in the blood and spleen is important to estimate the state at the time of death from a decaying body. Therefore, in the present study, the correlation between ketone bodies in the blood and spleen of the deceased was explored. Ketone bodies (beta-hydroxybutyric acid [BHB] and acetone) in the blood and spleen were analyzed and compared from autopsies (>100 mg·L^-1 BHB, blood basis) conducted at the Daejeon Forensic Research Institute from June to December 2021. Moreover, the concentration of ketone bodies in the spleen juice and tissues was compared assuming the scenario of extreme decomposition. Ketone retention concentration in the blood and spleen was positively correlated, and the ratio of BHB concentration in the spleen to BHB concentration in the blood ranged from 0.52 to 1.08 (mean = 0.85 ± 0.12), although the ratio may vary depending on the degree of decomposition of the corpse.