• Microbiology and Biotechnology Letters
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• v.27 no.2
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• pp.159-165
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• 1999

Pseudomonas aeruginosa JRT-4 strain was used as a biosurfactant-producing microorganism in this study. It was one of the microorganisms isolated from the sewage sludge, the main and branch streams of Han river. The surface tension of the culture broth of P. aeruginosa JRT-4 decreased to 30mN/m. The crude biosurfactant was obtained from the culture broth by acid precipitation, solvent extraction, evaporation, and freeze drying. The CMC value of the crude biosurfactant was 0.006%(w/v). From analysis of the chemical structure of biosurfactant, it was determined as rhamnolipid 1 and 3 structures by FAB mass spectrometer. In the washing test for artificially contaminated textiles, the biosurfactant showed better bleachness than the two chemically synthesized surfactant, LAS and SLES. Finally, the biodegradation and ecotoxidolorical tests showed that the biosurfactant was readily biodegradable in the environment and a mild material for microorganisms and green algae.

• Microbiology and Biotechnology Letters
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• v.22 no.1
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• pp.92-98
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• 1994

The bacteria which secrete surface-active agent and decrease the surface tension of culture broth were isolated from soil samples. Among them, biosurfactant producing strain KK-7 was selected and emulsification was also detected. The KK-7 produced biosurfactant not only lipid but also glucose by using carbon source. Taxonomical characterization tests have demostrated the strain KK-7 to be Pseudomonas aeruginosa. The media composition of the P. aeruginosa KK-7 for the biosurfactant production was 1% glucose, 0.5% tryptone, 0.2% yeast extract, 0.15% potas sium phosphate mono-dibasic, 0.05% MgSO$_{4}$, initial pH 8.5, at 30$\circ $C for 2 days. In this condition, the concentration of biosurfactant was reached CMC 5 in the culture broth. Surface active material was produced maximum at stationary8 phase, but emulsification power was higher at log phase than stationary phase. It was considered that P. aeruginosa KK-7 produced biosurfactant more than one type having defferent properties and each maximum production time was different. The minimun surface tension of biosurfactant in 50 mM Tris buffer (pH8.0) was 28 dyn/cm, and CMC was 1 g/L.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.3
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• pp.389-393
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• 2002

Among the bacterial strains isolated from chungkook-jang, Bacillus subtilis CH-1, Bacills circulans K-1 and Bacillus subtitis (natto) N-1, Bacillus subtitis CH-1 showed the highest productivity of biosufactant. A-medium was selected for the basal medium in the large scale production of biosurfactant, and modified to synthetic medium which containing 2% glucose, 0.3% soy peptone, and mineral salts. The surface tension was reduced to maximal value after 96 hr after fermentation, about the 43% of initial tension. Temperature and initial pH of medium was not critical factor for the biosurfactant production. The yield of crude biosurfactant was 6 g/L under the optimum condition.

• Journal of Life Science
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• v.14 no.2
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• pp.320-324
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• 2004

The objective of this study was investigate the characteristic of biosurfactant produced from the isolated strain. The strain was isolated from soil samples and identified as Bacillus sp. TBM 911-5 by physiological characteristics and the partial nucleotide sequence analysis of 16S rDNA. We measured the surface tension every 6 hours for 80 hours. The surface tension of the culture filtrate of Bacillus sp. TBM 911-5 was decreased to 29 mN/m. Biosurfactant concentration was determined by diluting the culture filtrate until the critical micelle concentration (CMC). The biosurfactant emulsified hydrocarbons, vegetable oil and crude oil. Using soybean oil as substrate, the maximum emulsification activity and stability was obtained from the biosurfactant. The biosurfactant produced from Bacillus sp. TBM 911-5 had strong properties as an emulsifying agent and an emulsion-stabilizing agent.

• Journal of Life Science
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• v.15 no.5 s.72
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• pp.679-684
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• 2005

The objective of this study was investigate the characteristic of biosurfactant produced from the iso-lated strain. The strain was isolated from soli samples of Duck-Yu Mountain and it was identified as Bacillus atrophaeus DYL-130 by 16S rDNA and gyrA gene nucleotide sequence analysis. The surface ten-sion of culture filtrate of Bacillus atrophaeus DYL-130 decreased to 28 mN/m and its biosurfactant con-centration was determined by diluting the culture filtrate until the critical micelle concentration (CMC). The emulsifying activity and stability of crude biosurfactant was measured by using water-immiscible hydrocarbons and oils as substrate. The biosurfactant was purified by affinity chromatography and the surface activity of purified biosurfactant was measured by drop-collapsing method and it could be effectively emulsify toluene.

• KSBB Journal
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• v.17 no.3
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• pp.302-306
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• 2002

The chemical analysis and surface chemical properties of biosurfactant formed by Rhodococcus sp. strain IGTS8, which is widely used in biodesulfurization process, in hexadecane/water mixture have been studied. For the chemical analysis, TLC technique was employed. The surface tension, CMC, and emulsion stability of biosurfactant solution were also investigated. The major components of biosurfactant formed by Rhodococcus sp. strain IGTS8 were glucose mycolate and trehalose monomycolate. The CMC of aqueous biosurfactant solution was 0.1 ~0.15 g/100 mL of Water at pH 6.0-6.5 and pH 10~10.5. But the demulsification was faster at pH 10 than at pH 6.3.

• Journal of Microbiology and Biotechnology
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• v.33 no.9
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• pp.1238-1249
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• 2023

In this study, we sought to investigate the production and optimization of biosurfactants by soil fungi isolated from petroleum oil-contaminated soil in Saudi Arabia. Forty-four fungal isolates were isolated from ten petroleum oil-contaminated soil samples. All isolates were identified using the internal transcribed spacer (ITS) region, and biosurfactant screening showed that thirty-nine of the isolates were positive. Aspergillus niger SA1 was the highest biosurfactant producer, demonstrating surface tension, drop collapsing, oil displacement, and an emulsification index (E₂₄) of 35.8 mN/m, 0.55 cm, 6.7 cm, and 70%, respectively. This isolate was therefore selected for biosurfactant optimization using the Fit Group model. The biosurfactant yield was increased 1.22 times higher than in the nonoptimized medium (8.02 g/l) under conditions of pH 6, temperature 35℃, waste frying oil (5.5 g), agitation rate of 200 rpm, and an incubation period of 7 days. Model significance and fitness analysis had an RMSE score of 0.852 and a p-value of 0.0016. The biosurfactant activities were surface tension (35.8 mN/m), drop collapsing (0.7 cm), oil displacement (4.5 cm), and E₂₄ (65.0%). The time course of biosurfactant production was a growth-associated phase. The main outputs of the mathematical model for biomass yield were Yx/s (1.18), and µ_max (0.0306) for biosurfactant yield was Y_p/s (1.87) and Y_p/x (2.51); for waste frying oil consumption the So was 55 g/l, and Ke was 2.56. To verify the model's accuracy, percentage errors between biomass and biosurfactant yields were determined by experimental work and calculated using model equations. The average error of biomass yield was 2.68%, and the average error percentage of biosurfactant yield was 3.39%.

• KSBB Journal
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• v.13 no.5
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• pp.511-517
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• 1998

Temperature and pH conditions were studied for an effective biosurfactant production by Pseudomonas aeruginosa YPJ-80. Efficient methods of biosurfactant separation were also investigated. pH-uncontrolled experiments at 35$^{\circ}C$ and an initial pH of 8 resulted in the best cell growth (3.6 g/L) and biosurfactant production (0.073 g biosurfactant/g cell). Biosurfactant separation was most efficient using solvent extraction with chloroform/methanol (2:1 vol%) followed by acidification using 1N HCl.

• Microbiology and Biotechnology Letters
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• v.23 no.2
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• pp.229-235
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• 1995

The surface tension-decreasing biosurfactant was purified from Rhodotorula muciloginosa G-1. The purification procedure was the solvent extraction of culture broth. To ensure complete extraction, the sample was extracted twice with equal volume of ethylacetate. The crude solution was washed with n-hexane to remove unconsumed soybean oil. The crude sample of biosurfactant was applied to Silica gel column chromatography equilibrated with chloroform, and eluted with chloroform : methanol gradient. Serveral solvent system was used to developed the thin layer chromatography (TLC). The purified biosurfactant sample gave one spot (Rf 0.78). It was estimated that biosurfactant was glycolipid about having M.W.1,500 with standard of polyethyleneglycol by Sephadex LH-20 column chromatography.

• Microbiology and Biotechnology Letters
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• v.22 no.6
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• pp.593-598
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• 1994

A bacterium KL-57 which exhibited biosurfactant activity was isolated. This bacterium was identified as Bacillus subtilis. The biosurfactant-producing gene of B. subtilis KL-57 was cloned into R subtilis MI113 by using plasmid pTB523. The plasmid DNA from the clone was found to carry a 18 kb PstI insert. The biosurfactant-producing gene was cleaved into 4 fragments by SmaI, 3 fragments by PvulI or EcoRl, 4 fragments by PvulI and EcoRI double digestion, 5 fragments by AccI, and 2 fragments by KpnI, HindIII or BamHI. By subcloning the 18 kb Pstl insert, a 2.3 kb EcoRl fragment conferred the biosurfactant producing activity on B. subtilis cells. The 2.3 kb had one HindIII cleave site. But Two fragments, which corresponds HindIII/EcoRl termini, exhibited no biosurfactant activity.