• Korean Journal of Environmental Agriculture
• /
• v.29 no.2
• /
• pp.176-183
• /
• 2010

Endosulfan degrading ability of Klebsiella oxytoca KE-8 immobilized by entrapment with activated carbon was examined. Endosulfan degradation by the immobilized bacterial strains on several different activated carbon based support materials was investigated. Based on results, activated carbon ($8\times30$ mesh) was chosen as a support material. The immobilized Klebsiella oxytoca KE-8 with the cell density of 4 mg $g^{-1}$ (dry weight) degraded 22.18 ug $ml^{-1}$ endosulfan within 5 days at pH 7.0, $30^{\circ}C$ in batch shake flask cultures. Also, we an experimented recycle packed bed column mode and continuous packed bed column mode for endosulfan degradation. Under optimum operation condition, the immobilized cells in a laboratory scale pack bed column with support beads were able to degrade endosulfan completely in defined minimal salt medium at a maximum rate of 129.6 ug $ml^{-1}$ per day. Moreover, the endosulfan degradation activity could be demonstrated at $4^{\circ}C$ for one month without significant decrease in activity. Results of this study suggest that immobilized cells of Klebsiella oxytoca KE-8 might be applicable to endosulfan contaminated site.

• Korean Journal of Food Science and Technology
• /
• v.20 no.5
• /
• pp.724-731
• /
• 1988

For a study on the production of ${\gamma}-linolenic$ acid(GLA) by microorganisms, fifteen strains of Mucorales obtained from culture stocks and ten isolate strains were compared in their cell growth, lipid content, fatty acid composition and pellet size formed in shake flask culture. Among the fungi examined, the isolated fungus, designated as FB-354, was found to be the most suitable one for the production of GLA mainly due to its high contents of lipid, 29.9% of dry cell weight and GLA, 16.8% of the total fatty acids. The strain FB-354 was tentatively identified as Mucor sp. on the basis of morphological characteristics. Fungal oil produced by Mucor sp. FB-354 was fractionated into 81.1% of neutral lipid, 7.2% of glycolipid, and 11.8% of phospholipid. Although the GLA content in the phospholipid fraction was as high as 21.4%, most of the GLA was found in the neutral lipid fraction.

• Journal of Microbiology and Biotechnology
• /
• v.26 no.4
• /
• pp.700-709
• /
• 2016

The mitogen-activated protein kinase HOG1 (high-osmolarity glycerol response pathway) plays a crucial role in the response of yeast to hyperosmotic shock. Trichosporonoides oedocephalis produces large amounts of polyols (e.g., erythritol and glycerol) in a culture medium. However, the effects of HOG1 gene knockout and environmental stress on the production of these polyols have not yet been studied. In this study, a To-HOG1 null mutation was constructed in T. oedocephalis using the loxP-Kan-loxP/Cre system as replacement of the targeted genes, and the resultant mutants showed much smaller colonies than the wild-type controls. Interestingly, compared with the wild-type strains, the results of shake-flask culture showed that To-HOG1 null mutation increased erythritol production by 1.44-fold while decreasing glycerol production by 71.23%. In addition, this study investigated the effects of citric acid stress on the T. oedocephalis HOG1 null mutants and the wild-type strain. When the supplementation of citric acid in the fermentation medium was controlled at 0.3% (w/v), the concentration of erythritol produced from the wild-type and To-HOG1 knockout mutant strains improved by 18.21% and 21.65%, respectively.

• Journal of Microbiology and Biotechnology
• /
• v.23 no.9
• /
• pp.1260-1268
• /
• 2013

A series of experiments were carried out with three native strains of microalgae to measure growth rates, biomass, and lipid productivities. Scenedesmus sp. IMMTCC-6 had better biomass growth rate and higher lipid production. The growth, lipid accumulation, and carbon dioxide ($CO_2$) consumption rate of Scenedesmus sp. IMMTCC-6 were tested under different NaOH concentrations in modified BBM. The algal strain showed the maximum specific growth rate (0.474/day), biomass productivity (110.9 mg $l^{-1}d^{-1}$), and $CO_2$ consumption rate (208.4 mg $l^{-1}d^{-1}$) with an NaOH concentration of 0.005 M on the $8^{th}$ day of cultivation. These values were 2.03-, 6.89-, and 6.88-fold more than the algal cultures grown in control conditions (having no NaOH and $CO_2$). The $CO_2$ fixing efficiency of the microalga with other alternative carbon sources like $Na_2CO_3$ and $NaHCO_3$ was also investigated and compared. The optimized experimental parameters at shake-flask scale were implemented for scaling up the process in a self-engineered photobioreactor. A significant increase in lipid accumulation (14.23% to 31.74%) by the algal strain from the logarithmic to stationary phases was obtained. The algal lipids were mainly composed of $C_{16}/C_{18}$ fatty acids, and are desirable for biodiesel production. The study suggests that microalga Scenedesmus sp. IMMTCC-6 is an efficient strain for biodiesel production and $CO_2$ biofixation using stripping solution of NaOH in a cyclic process.

• Journal of Microbiology and Biotechnology
• /
• v.12 no.1
• /
• pp.1-7
• /
• 2002

The effects of DO and pH on the mass production of pullulan with high molecular weight and the morphology of A. pullulans ATCC 42023 were evaluated. A. pullulans showed a maximum production of pullulan (11.98 g/l) when the initial pH of the culture broth was 6.5 in a shake-flask culture. In a batch culture, the mixture of a yeast-like and mycelial cell forms was found at a pH of 4.5, and the maximum production of pullulan (13.31 g/l) was obtained. However, a high proportion of high molecular weight pullulan (M.W.>2,000,000) was produced at a pH of 6.5, with a yeast-like morphology. The maximum pullulan production yield ($51\%$) was obtained at a pH noncontrol (initial pH 6.5) and DO control (above $50\%$) condition. Pullulan degrading enzyme was activated when the pH of the broth was lower than 5.0 and the portion of low molecular weight pullulan was increased. The formation of a black pigment was observed at an initial stationary phase, at 40 h of fermentation. Therefore, the fermentation should be carried out in a pH noncontrol (initial pH of 6.5) and DO control (above $50\%$) condition, and should be harvested before reaching the stationary phase (around 40 h) for the production of high molecular weight pullulan.

• Environmental Engineering Research
• /
• v.25 no.1
• /
• pp.62-70
• /
• 2020

Here in this work, a 4-chlorophenol (4-CP)-degrading bacterial strain Bacillus subtilis (B. subtilis) MF447840.1 was isolated from the drain outside the Hyundai car service center, Agartala, Tripura, India. 16S rDNA technique used carried out for genomic recognition of the bacterial species. Isolated bacterial strain was phylogenetically related with B. subtilis. This strain was capable of breaking down both phenol and 4-CP at the concentration of 1,000 mg/L. Also, the isolated strain can able to metabolize five diverse aromatic molecules such as 2-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol, 4-nitrophenol, and pentachlorophenol for their growth. An extensive investigation was performed to portray the kinetics of cell growth along with 4-CP degradation in the batch study utilizing 4-CP as substrate. Various unstructured models were applied to evaluate the intrinsic kinetic factors. Levenspiel's model demonstrates a comparatively enhanced R² value (0.997) amongst every analyzed model. The data of specific growth rate (μ), saturation constant (K_S), and Y_X/S were 0.11 h^-1, 39.88 mg/L, along with 0.53 g/g, correspondingly. The isolated strain degrades 1,000 mg/L of 4-CP within 40 h. Therefore, B. subtilis MF447840.1 was considered a potential candidate for 4-CP degradation.

• Applied Chemistry for Engineering
• /
• v.8 no.4
• /
• pp.660-666
• /
• 1997

The production of doxorubicin by a mutant of Streptomyces peucetius subsp. caesius was studied. The optimal culture conditions, such as inoculum size and medium composition were established to improve the productivity of doxorubicin. The optimal medium composition was found to be 4% maltose, 0.5% HEPES, 0.02% $K_2HPO_4$, 0.01% $MgSO_4$. As an antiform agent, 0.001% KG(10% Adekanol+10% Silicone) was suitable one among various agents. Culture was carried out in 2.5 L jar-fermenter with different aeration rates of 1.5, 1.0, and 1.5 v/v min. The maximum production of doxorubicin(29 mg/l) was obtained at 1.5 v/v min of aeration rate, and even at 1.0 v/v min, the production of doxorubicin was increased up to 15% compared with that of shake-flask culture.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.21 no.3
• /
• pp.263-269
• /
• 1992

Radish green juice was used as a dual source for the production of plant protein precipitate and Candida utilis biomass. Precipitates ranging from 10.0 to 16.5g were obtained from a liter of radish green juice by heating at 80-10$0^{\circ}C$C for 1 to 10 min or by modification of the pH of radish green juice. Crude protein content of the precipitate was between 25 and 38%. The residue remaining after protein precipitation was used in turn for the cultivation of the yeast, C. utilis, in order to produce yeast biomass. C. utilis grew well in radish green residual juice and completed growth within 24 hr at 3$0^{\circ}C$ and 200rpm in shake flask experiments. Maximum dry cell weight obtainable from a liter of radish green residual juice was 19.5g, when the yeast was grown on the juice residue diluted 3 times or more with water to make sugar content be equal to or less than about 1.0%. Supplementation of 3-fold diluted radish green residual juice with yeast extract and (NH$_4$)SO$_4$ enhanced yeast biomass production and cell protein content significantly. Total high protein material obtainable from a liter of radish green juice was 33.0g.

• 한국생물공학회:학술대회논문집
• /
• 2005.10a
• /
• pp.644-648
• /
• 2005

Dextranase (${\alpha}$-1,6-D-glucan-6-glucanogydrolase:E.C. 3.2.1.11) catalyzes the hydrolysis of ${\alpha}$-(1.6) linkages of dextran. A lsd1 gene encoding an extracellular dextranase was isolated from the genomic DNA of L. starkeyi. The lsd11 gene is a synthetic dextranase (lsd1) after codon optimization for gene expression with Pichia pastoris system. A open reading frame of lsd11 gene was 1827 bp and it was inserted into the pPIC3.5K expression vector. The plasmid linearized by Sac I was integrated into the 5'AOX region of the chromosomal DNA of P. pastoris. The lsd11 gene fragment encoding a mature protein of 608 amino acids with a predicted molecular weight of 70 kDa, was expressed in the methylotrophic yeast P. pastoris by controling the alcohol oxidase-1 (AOX1) promoter. The recombinant lds11 was optimized by using the shake-flask expression and upscaled using fermentation technology. More than 9.8 mg/L of active dextranase was obtained after induction by methanol. The optimum pH of LSD11 was found to be 5.5 and the optimum temperature $28^{\circ}C$.

• Bulletin of the Korean Chemical Society
• /
• v.25 no.5
• /
• pp.639-646
• /
• 2004

Metal treated activated carbons are prepared using various metals. Adsorption behaviors, morphologies, as well as antibacterial effects of metal treated samples are compared before and after solvent washing. Adsorption isotherms are used to characterize the porous structure of metal treated activated carbons before and after the solvent washing with acetone or ethyl alcohol. From these data, it is noticed that the changes in physicochemical properties of metal treated activated carbons depend on the solvents employed. Similar results are observed from BET data obtained from nitrogen adsorption isotherms. From scanning electron microscopy (SEM) studies, the changes in shape and size of metal particles are observed after the samples are washed with solvents. These changes result in different blocking effects, which, in turn, affect the adsorption behavior of metal treated activated carbons. X-ray diffraction (XRD) patterns of the samples treated with different metals are different each other. High intense sharp peaks attributed to metals are observed from silver treated samples, while the peaks are not observed from copper treated samples. To compare thermodynamic behavior of metal treated activated carbons washed with different type of solvents, differential scanning calorimetric (DSC) analysis is carried out. The analysis shows similar endothermic curves for all of the samples. Finally, antibacterial effects of metal treated activated carbon against Escherichia coli are discussed. Comparing the effects among the metals employed, highest effects are obtained from Cd, while lowest effects are obtained from Cu. Antibacterial activity becomes higher with the increase of the amount of metals treated, Optimum concentrations of metals to treat activated carbons, obtained from a shake flask test, are known to be 0.4, 0.1, and 0.6 moles for Ag, Cd, and Cu, respectively.