Construction and evaluation of nagR-nagAa::lux fusion strains in biosensing for salicylic acid derivatives.

Mitchell, Robert J,Gu, Man Bock Humana Press ; Humana Press ; OCLC 2005 Applied biochemistry and biotechnology Vol.120 No.3

<P>The NagR protein is a response regulatory protein found in the bacterium Ralstonia sp. U2 that is involved in sensing for salicylic acid and the subsequent induction of the operon just upstream of its gene. The genes encoded for in this operon are involved in the degradation of salicylic acid. Escherichia coli strain RFM443 carrying a fusion of the Photorhabdus luminescens luxCDABE operon with the nagR gene and upstream region of the nagAa gene was constructed and characterized with respect to its optimum temperature, its response time and kinetics, and its ability to detect numerous benzoic acid derivatives. Although capable of detecting 0.5 mM salicylic acid at any temperature between 28 and 40 degrees C, this E. coli strain, labeled DNT5, showed its greatest relative activity at 30 degrees C, i.e., the temperature at which the largest induction was seen. Furthermore, experiments done with numerous benzoic acid derivatives found the NagR protein to be responsive to only a few of the compounds tested, including salicylic acid and 3-methyl salicylic acid, and acetyl salicylic acid was the strongest inducer. The lower limits of detection for these compounds with E. coli strain DNT5 were also established, with the native inducer, salicylic acid, giving the most sensitive response and detectable down to a concentration of about 2 microM. A second lux fusion plasmid was also constructed and transformed into an NahR background, Pseudomonas putida KCTC1768. Within this strain, NAGK-1768, the supplemental activity of the NahR protein on the nagAa promoter, was shown to extend both the range of chemicals detected and the sensitivity.</P>

Synthesis of poly(sorbitan methacrylate) hydrogel by free-radical polymerization.

Jeong, Gwi-Taek,Lee, Kyoung-Min,Yang, Hee-Seung,Park, Seok-Hwan,Park, Jae-Hee,Sunwoo, Changshin,Ryu, Hwa-Won,Kim, Doman,Lee, Woo-Tae,Kim, Hae-Sung,Cha, Wol-Seog,Park, Don-Hee Humana Press ; Humana Press ; OCLC 2007 Applied biochemistry and biotechnology Vol.137 No.1

<P>Hydrogels are materials with the ability to swell in water through the retention of significant fractions of water within their structures. Owing to their relatively high degree of biocompatibility, hydrogels have been utilized in a host of biomedical applications. In an attempt to determine the optimum conditions for hydrogel synthesis by the free-radical polymerization of sorbitan methacrylate (SMA), the hydrogel used in this study was well polymerized under the following conditions: 50% (w/v) SMA as monomer, 1% (w/w) alpha, alpha'-azo-bis(isobutyro-nitrile) as thermal initiator, and 1% (w/w) ethylene glycol dimethacrylate as cross-liking agent. Under these conditions, the moisture content of the polymerized SMA hydrogel was higher than in the other conditions. Moreover, the moisture content of the poly(SMA) hydrogel was also found to be higher than that of the poly(methyl methacrylate [MMA]) hydrogel. When the Fourier transform-infrared spectrum of poly(SMA) hydrogel was compared with that of poly(MMA) hydrogel, we noted a band at 1735-1730/cm, which did not appear in the Fourier transform-infrared spectrum of poly(MMA). The surface of the poly(SMA) hydrogel was visualized through scanning electron microscopy, and was uniform and clear in appearance.</P>

Lipase-catalyzed transesterification of rapeseed oil for biodiesel production with tert-butanol.

Jeong, Gwi-Taek,Park, Don-Hee Humana Press ; Humana Press ; OCLC 2008 Applied biochemistry and biotechnology Vol.148 No.1

<P>Biodiesel is a fatty acid alkyl ester that can be derived from any vegetable oil or animal fat via the process of transesterification. It is a renewable, biodegradable, and nontoxic fuel. In this paper, we have evaluated the efficacy of a transesterification process for rapeseed oil with methanol in the presence of an enzyme and tert-butanol, which is added to ameliorate the negative effects associated with excess methanol. The application of Novozym 435 was determined to catalyze the transesterification process, and a conversion of 76.1% was achieved under selected conditions (reaction temperature 40 degrees C, methanol/oil molar ratio 3:1, 5% (w/w) Novozym 435 based on the oil weight, water content 1% (w/w), and reaction time of 24h). It has also been determined that rapeseed oil can be converted to fatty acid methyl ester using this system, and the results of this study contribute to the body of basic data relevant to the development of continuous enzymatic processes.</P>

Biodiesel production from various oils under supercritical fluid conditions by Candida antartica lipase B using a stepwise reaction method.

Lee, Jong Ho,Kwon, Cheong Hoon,Kang, Jeong Won,Park, Chulhwan,Tae, Bumseok,Kim, Seung Wook Humana Press ; Humana Press ; OCLC 2009 Applied biochemistry and biotechnology Vol.156 No.1

<P>In this study, we evaluate the effects of various reaction factors, including pressure, temperature, agitation speed, enzyme concentration, and water content to increase biodiesel production. In addition, biodiesel was produced from various oils to establish the optimal enzymatic process of biodiesel production. Optimal conditions were determined to be as follows: pressure 130 bar, temperature 45 degrees C, agitation speed 200 rpm, enzyme concentration 20%, and water contents 10%. Among the various oils used for production, olive oil showed the highest yield (65.18%) upon transesterification. However, when biodiesel was produced using a batch system, biodiesel conversion yield was not increased over 65%; therefore, a stepwise reaction was conducted to increase biodiesel production. When a reaction medium with an initial concentration of methanol of 60 mmol was used and adjusted to maintain this concentration of methanol every 1.5 h during biodiesel production, the conversion yield of biodiesel was 98.92% at 6 h. Finally, reusability was evaluated using immobilized lipase to determine if this method was applicable for industrial biodiesel production. When biodiesel was produced repeatedly, the conversion rate was maintained at over 85% after eight reuses.</P>

Mobilization and biodegradation of 2-methylnaphthalene by amphiphilic polyurethane nano-particle.

Kim, Young-Bum,Kim, Ju-Young,Kim, Eun-ki Humana Press ; Humana Press ; OCLC 2009 Applied biochemistry and biotechnology Vol.159 No.1

<P>Amphiphilic polyurethane (APU) nano-particle enhanced the mobilization of 2-methylnaphthalene (2-MNPT) in soil. Significant increase in the solubility of 2-MNPT was achieved. The molar solubilization ratio was 0.4 (mole 2-MNPT/mole APU). Simple precipitation of APU particle by 2 N CaCl(2) recovered 95% of APU particle and 92% of 2-MNPT simultaneously. Also, 2-MNPT, which was entrapped inside the APU particle, was directly degraded by Acinetobacter sp. as same efficiency as without APU particle. These results showed the potentials of APU particle in the mobilization and biodegradation of hydrophobic compounds from soil.</P>

Tagatose production with pH control in a stirred tank reactor containing immobilized L-arabinose rom Thermotoga neapolitana.

Lim, Byung-Chul,Kim, Hye-Jung,Oh, Deok-Kun Humana Press ; Humana Press ; OCLC 2008 Applied biochemistry and biotechnology Vol.149 No.3

<P>Chitopearl beads were used as immobilization supports for D-tagatose production from D-galactose by L-arabinose isomerase from Thermotoga neapolitana because chitopearl beads were more stable than alginate beads at temperatures above 60 degrees C. The pH and temperature for the maximum isomerization of galactose were 7.5 and 90 degrees C, respectively. In thermostability experiments, the half-lives of the immobilized enzyme at 70, 75, 80, 85, and 90 degrees C were 388, 106, 54, 36, and 22 h, respectively. The reaction temperature was determined to be 70 degrees C because the enzyme is highly stable up to 70 degrees C during the reaction. When the reaction time, galactose concentration, and temperature were increased, the pH of a mixture containing enzyme and galactose decreased by the Maillard reaction, resulting in decreased tagatose production. With pH control at 7.5, tagatose production (138 g/L) at 70 degrees C in a stirred tank reactor containing immobilized enzyme and 300 g/L galactose increased two times higher, comparing that without pH control.</P>

Optimization of biodiesel production from castor oil using response surface methodology.

Jeong, Gwi-Taek,Park, Don-Hee Humana Press ; Humana Press ; OCLC 2009 Applied biochemistry and biotechnology Vol.156 No.1

<P>The short supply of edible vegetable oils is the limiting factor in the progression of biodiesel technology; thus, in this study, we applied response surface methodology in order to optimize the reaction factors for biodiesel synthesis from inedible castor oil. Specifically, we evaluated the effects of multiple parameters and their reciprocal interactions using a five-level three-factor design. In a total of 20 individual experiments, we optimized the reaction temperature, oil-to-methanol molar ratio, and quantity of catalyst. Our model equation predicted that the following conditions would generate the maximum quantity of castor biodiesel (92 wt.%): a 40-min reaction at 35.5 degrees C, with an oil-to-methanol molar ratio of 1:8.24, and a catalyst concentration of 1.45% of KOH by weight of castor oil. Subsequent empirical analyses of the biodiesel generated under the predicted conditions showed that the model equation accurately predicted castor biodiesel yields within the tested ranges. The biodiesel produced from castor oil satisfied the relevant quality standards without regard to viscosity and cold filter plugging point.</P>

Optimization of oligosaccharide synthesis from cellobiose by dextransucrase.

Kim, Misook,Day, Donal F Humana Press ; Humana Press ; OCLC 2008 Applied biochemistry and biotechnology Vol.148 No.1

<P>There is a growing market for oligosaccharides as sweeteners, prebiotics, anticariogenic compounds, and immunostimulating agents in both food and pharmaceutical industries. Interest in novel carbohydrate-based products has grown because of their reduced toxicity and low immune response. Cellobiose is potentially valuable as a nondigestible sugar. The reaction of cellobiose, as an acceptor with a sucrose as a donor, catalyzed by a dextransucrase from Leuconostoc mesenteroides B-512FMCM, produced a series of cellobio-oligosaccharides. This production system was optimized using a Box-Behnken experimental design for 289 mM of sucrose and 250 mM of cellobiose and 54 U of the enzyme at pH 5.2 and 30 degrees C, to produce maximum yields of oligosaccharide.</P>

Hydrolysis of ammonia-pretreated sugar cane bagasse with cellulase, beta-glucosidase, and hemicellulase preparations.

Prior, Bernard A,Day, Donal F Humana Press ; Humana Press ; OCLC 2008 Applied biochemistry and biotechnology Vol.146 No.1

<P>Sugar cane bagasse consists of hemicellulose (24%) and cellulose (38%), and bioconversion of both fractions to ethanol should be considered for a viable process. We have evaluated the hydrolysis of pretreated bagasse with combinations of cellulase, beta-glucosidase, and hemicellulase. Ground bagasse was pretreated either by the AFEX process (2NH(3): 1 biomass, 100 degrees C, 30 min) or with NH(4)OH (0.5 g NH(4)OH of a 28% [v/v] per gram dry biomass; 160 degrees C, 60 min), and composition analysis showed that the glucan and xylan fractions remained largely intact. The enzyme activities of four commercial xylanase preparations and supernatants of four laboratory-grown fungi were determined and evaluated for their ability to boost xylan hydrolysis when added to cellulase and beta-glucosidase (10 filter paper units [FPU]: 20 cellobiase units [CBU]/g glucan). At 1% glucan loading, the commercial enzyme preparations (added at 10% or 50% levels of total protein in the enzyme preparations) boosted xylan and glucan hydrolysis in both pretreated bagasse samples. Xylanase addition at 10% protein level also improved hydrolysis of xylan and glucan fractions up to 10% glucan loading (28% solids loading). Significant xylanase activity in enzyme cocktails appears to be required for improving hydrolysis of both glucan and xylan fractions of ammonia pretreated sugar cane bagasse.</P>

Sequential and simultaneous statistical optimization by dynamic design of experiment for peptide overexpression in recombinant Escherichia coli.

Lee, Kwang-Min,Rhee, Chang-Hoon,Kang, Choong-Kyung,Kim, Jung-Hoe Humana Press ; Humana Press ; OCLC 2006 Applied biochemistry and biotechnology Vol.135 No.1

<P>The production of recombinant anti-HIV peptide, T-20, in Escherichia coli was optimized by statistical experimental designs (successive designs with multifactors) such as 2(4-1) fractional factorial, 2(3) full factorial, and 2(2) rotational central composite design in order. The effects of media compositions (glucose, NPK sources, MgSO4, and trace elements), induction level, induction timing (optical density at induction process), and induction duration (culture time after induction) on T-20 production were studied by using a statistical response surface method. A series of iterative experimental designs was employed to determine optimal fermentation conditions (media and process factors). Optimal ranges characterized by %T-20 (proportion of peptide to the total cell protein) were observed, narrowed down, and further investigated to determine the optimal combination of culture conditions, which was as follows: 9, 6, 10, and 1 mL of glucose, NPK sources, MgSO4, and trace elements, respectively, in a total of 100 mL of medium inducted at an OD of 0.55-0.75 with 0.7 mM isopropyl-beta-D-thiogalactopyranoside in an induction duration of 4 h. Under these conditions, up to 14% of T-20 was obtained. This statistical optimization allowed the production of T-20 to be increased more than twofold (from 6 to 14%) within a shorter induction duration (from 6 to 4 h) at the shake-flask scale.</P>