• Journal of Microbiology and Biotechnology
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• v.11 no.2
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• pp.342-345
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• 2001

A bacterial strain PH-4, which produces an enzyme catalyzing the degradation of crosslinked poly(${\gamma}$-glutamic acid) hydrogels, was isolated and identified as a Flavobacterium sp. The enzyme was obtained by the sonication of the bacterial cells preincubated in a Bouillon medium with shaking, without adding of poly(${\gamma}$-glutamic acid) as an inducer. The products of the hydrogel degraded by the crude enzyme agreed closely with the depolymerized materials in SDS-polyacrylamide gel electrophoresis using methylene blue staining, and with a glutamic acid monomer on thin-layer chromatography, thereby suggesting that strain PH-4 produced a kind of exohydrolase.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.12
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• pp.645-651
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• 2015

This paper presents an experimental study on the freeze drying process for poly ${\gamma}$ glutamic acid. The physical properties of poly ${\gamma}$ glutamic acid are measured during the freeze-drying process. The moisture contents of poly ${\gamma}$ glutamic acid according to the glass transient temperature are obtained by DSC (Differential Scanning Calorimetry) analysis. The end point of primary drying for the poly ${\gamma}$ glutamic acid with a thickness of 3 mm is obtained by measuring the thickness of the dried layer, the amount of moisture evaporation, the moisture content, and the pressure in the drying vacuum chamber during the freeze-drying process. By considering the variation in the glass transient temperature with respect to the moisture content of the material, a control schedule for the heating plate temperature is suggested during the secondary drying process.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.3
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• pp.357-362
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• 2005

Poly-${\gamma}$-glutamic acid (${\gamma}-PGA$), which is extracted from fermented soybeans, is a high molecular weight, adhesive, and negatively charged(anionic) polymer. Recently, ${\gamma}-PGA$ has gained attention due to its potential as polymer. The objectives of this study were to examine the applicability of ${\gamma}-PGA$ as a coagulant and/or a coagulant aid, to evaluate the efficiency of ${\gamma}-PGA$ for the removal of Organic and Ammonium substance in wastewater treatment. The effect of coagulation was evaluated for the removal of SS and organic matter using poly aluminum chloride(PACI) as well as newly developed ${\gamma}-PGA$. The maximum COD removal rate of 63% and the SS of 78% were occurred at the dosage of 50mg/L ${\gamma}-PGA$ only. The most effective removal for particulate and organic matter was occured when both PACI and ${\gamma}-PGA$ were applied at the rate of 20:1(10mg/L PACI and 0.5mg/L ${\gamma}-PGA$). When mixed with PACI, only small portion of ${\gamma}-PGA$ was enough to improve removal efficiencies of organic and particulate matter in wastewater. This result showed the positive potential of ${\gamma}-PGA$ as a new coagulant materials for wastewater treatment.

• Journal of Radiation Industry
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• v.6 no.2
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• pp.165-169
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• 2012

This study was conducted to determine the prevention effect of poly-gamma-glutamic acid (${\gamma}-PGA$) on tissue damage induced by gamma irradiation for development of xenograft. Porcine tendons were treated at various doses of ${\gamma}-PGA$ (0.1, 0.5, 1 and 5%) and then gamma-irradiated (30 kGy). Prevention effects on tissue damage were measured as the result of tensile strength, hydroxyproline contents and viscosity of ${\gamma}-PGA$. Tensile strength was remarkably decrease in gamma-irradiated porcine ligament, but increased by ${\gamma}-PGA$ treated one. Among the ${\gamma}-PGA$ treatment doses, 1% treated group showed the highest values of tensile strength compared to non-treated group. Hydroxyproline contents was significantly increased by gamma irradiation, but decreased by the ${\gamma}-PGA$ treatment. Particularly, 1 and 5% ${\gamma}-PGA$ treated group were exhibited lower values of hydroxyproline contents than other group. In the result of viscosity, gamma-irradiated ${\gamma}-PGA$ (1%) was remarkably increased. Base on the results, it demonstrated that gamma irradiation induces severe alteration of mechanical property and collagen contents on porcine ligament, but ${\gamma}-PGA$ can effectively prevent these tissue damage.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.45-46
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• 2000

After cell removal from fermentation broth the supernatant containing poly (${\gamma}-glutamic acid$) (${\gamma}-PGA$) was concentrated by ultrafiltration in order to reduce the amount of organic solvents such as methanol, ethanol, propanol required for the recover of ${\gamma}-PGA$ with precipitation. The concentration and volume reduction of cell-free solution by ultrafiltration could reduce 3 times the amount of ethanol for the recover of ${\gamma}-PGA$ from cell-free fermentation broth.

• The Korean Journal of Food And Nutrition
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• v.25 no.3
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• pp.677-684
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• 2012

A bacterium strain GS-2 isolated from the Korean traditional seasoning food, Chungkookjang and was determined to produce large amounts of ${\gamma}$-PGA with high productivity when provided with simple nutrients (L-glutamic acid 2.0%, glucose 1.0%, $NH_4Cl$ 0.5%, $KH_2PO_4$ 0.05%, $MgSO_4{\cdot}7H_2O$ 0.01%, pH 7.0). In this study, the culture medium for this strain was optimized for the production of ${\gamma}$-PGA. The Bacillus subtilis GS-2 required supplementation with L-glutamic acid and other nutrients for maximal production of ${\gamma}$-PGA. The optimal culture conditions for ${\gamma}$-PGA production were a 48 hr culture time, a temperature of $33^{\circ}C$ and initial pH of 6.5 by rotary shaking (220 rpm). A maximum ${\gamma}$-PGA production of 31.0 $g/{\ell}$ was obtained with L-glutamic acid (30 $g/{\ell}$), sucrose (the main carbon source, 30 $g/{\ell}$), $NH_4Cl$ (the main nitrogen source, 2.5 $g/{\ell}$), $KH_2PO_4$ (1.5 $g/{\ell}$) and $MgSO_4{\cdot}7H_2O$ (0.15 $g/{\ell}$) in the culture medium.

• Applied Biological Chemistry
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• v.40 no.3
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• pp.173-177
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• 1997

Bacillus licheniformis 9945a releases a natural ${\gamma}-poly(glutamic\;acid)({\gamma}-PGA)$ into fermentation broth and shows a mucoid phenotype on the solid agar medium. Transformation of mucoid cells of Bacillus species has not been simple and straightforward. The transpositional activity of Tn10 in B. licheniformis also has not been own either. Thus, a spontaneous non-mucoid derivative of the B. licheniformis was obtained first. Shuttle vector pHV1248 containing mini-Tn10 was introduced into the non-mucoid derivative by the method of protoplast transformation. The resulting transformant was reverted to the wild mucoid phenotype, and then mutated randomly with the mini-transposon by heat induction. Auxotrophs requiring arginine, lysine, or tryptophan were isolated by replica plating method. Southern blotting and DNA-DNA hybridzation analysis showed that these auxotrophs were generated by mini-Tn10 insertion into the chromosomal DNA. This method of transformation and mutation using pHV1248 would be useful for the generation of diverse mutants of B. licheniformis 9945a.(Received January 24,1997; accepted March 10, 1997)

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.3
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• pp.255-261
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• 2006

This study was Conducted to investigate the effect of ${\gamma}-PGA\;({\gamma}-poly\;glutamic\;acid)$ on Ca absorption and bone metabolism in rats. Weaned 4-week old male rats were fed Ca-deficient diets for 3 weeks after the adjustment period. Rats were divided into 6 groups and were fed experimental diets for four weeks. Experimental groups were basal (Ca deficient), control (Ca diet: Ca 0.45%), CP1(Ca 0.45%+casein phosphopeptide 1%), PG1(Ca 0.45%+gamma poly glutamic acid 1%), CPG (Ca 0.45%+casein phosphopeptide 1%+gamma poly glutamic acid 1%) and PG3(Ca 0.45%+gamma poly glutamic acid 3%). Though daily Ca intake and food intake of experimental groups showed no significant difference that of control group. The values of fecal Ca excretion and urinary Ca excretion in groups fed ${\gamma}-PGA$ were significantly lower than that in tile control group. The values of Ca absorption in groups fed ${\gamma}-PGA$ were significantly higher than that in the control group. The levels of femur Ca in ${\gamma}-PGA$ supplemented group were significantly increased compared to the control group. Also, breaking force of femur in ${\gamma}-PGA$ supplemented group showed about 40% increase compared to the control group. These results show that ${\gamma}-PGA$ supplement could be helpful to increase Ca absorption as well as to intensify the femur strength and to increase the Ca content of femur in rats.

• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.3
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• pp.251-257
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• 2006

The components of the media used to elicit the biosynthesis of $poly-{\gamma}-glutamic$ acid $({\gamma}-PGA)$ by Bacillus subtilis ZJU-7 were investigated, particularly the carbon and nitrogen sources Of the 7 carbon sources investigated, sucrose induced the highest rate of ${\gamma}-PGA$ productivity; among the nitrogen sources, tryptone had the best effect for ${\gamma}-PGA$ production. A $2^{6-2}$ fractional factorial design was used to screen factors that influence ${\gamma}-PGA$ production significantly, and a central composite design was finally adopted to formulate the optimal medium. ${\gamma}-PGA$ productivity improved approximately 2-fold when the optimal medium was used compared with the original nonoptimized medium, and volumetric productivity reached a maximum of 58.2 g/L after a 24-h cultivation period.

• Preventive Nutrition and Food Science
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• v.13 no.4
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• pp.354-361
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• 2008

A novel bacterium isolated from Cheonggukjang was identified as a glutamate-dependent Bacillus subtilis HA with 98.3% similarity to Bacillus subtilis Z99104. Optimization of poly-$\gamma$-glutamic acid ($\gamma$-PGA) production by modulating fermentation factors including carbon sources, nitrogen sources, inorganic salts and fermentation time was investigated. Optimum culture broth for $\gamma$-PGA production consisted of 3% glutamate, 3% glucose and various salts, resulting in the PGA production of 22.5 g/L by shaking culture for 72 hr at $37^{\circ}C$. Average molecular weight of $\gamma$-PGA was determined to be 1,220 kDa through MALLS analysis. The $\gamma$-PGA solution showed a typical pseudoplastic flow behavior, and a great decrease in consistency below pH 6.0 regardless of the same molecular weight of $\gamma$-PGA. The molecular weights of isolated $\gamma$-PGA were drastically decreased by heat treatment in various acidic conditions, resulting in different hydrolysis of $\gamma$-PGA. The consistency of $\gamma$-PGA solution was greatly decreased with increase heating time in acidic conditions.