• KSBB Journal
• /
• v.27 no.2
• /
• pp.127-130
• /
• 2012

In this study, the effects of pH, temperature, IPTG concentration and substrate (MSG) concentration on gamma-aminobutyric acid (GABA) production in engineered Escherichia coli were investigated. Glutamate decarboxylase and glutamate/GABA antiporter were overexpressed in GABA aminotransferase knock-out strain for GABA production. The result of optimization study showed the GABA bioconversion was optimized at pH 3.5, $30^{\circ}C$, 0.5 mM IPTG, 10 g/L MSG. At this condition, 5.23 g/L of final GABA concentration of was achieved from 10 g/L of MSG, which corresponded to a GABA yield of 85.77%.

• Journal of Microbiology and Biotechnology
• /
• v.26 no.8
• /
• pp.1348-1357
• /
• 2016

An enzymatic reaction system was developed and optimized for bioconversion of resveratrol from glucose. Liquid enzyme extracts were prepared from Alternaria sp. MG1, an endophytic fungus from grape, and used directly or after immobilization with sodium alginate. When the enzyme solution was used, efficient production of resveratrol was found within 120 min in a manner that was pH-, reaction time-, enzyme amount-, substrate type-, and substrate concentration-dependent. After the optimization experiments using the response surface methodology, the highest value of resveratrol production (224.40 μg/l) was found under the conditions of pH 6.84, 0.35 g/l glucose, 0.02 mg/l coenzyme A, and 0.02 mg/l ATP. Immobilized enzyme extracts could keep high production of resveratrol during recycling use for two to five times. The developed system indicated a potential approach to resveratrol biosynthesis independent of plants and fungal cell growth, and provided a possible way to produce resveratrol within 2 h, the shortest period needed for biosynthesis of resveratrol so far.

• Microbiology and Biotechnology Letters
• /
• v.17 no.3
• /
• pp.219-223
• /
• 1989

Effect of antifoam agents, silicone oil and neolin 302, was investigated on the production of prodnisolone by microbial $\Delta$$^1$-Dehydrogenation of hydrocortisone. The microbial process was conduct-ed by using a pseudo-crystallofermentation. By the hydrophobic-hydrophobic interaction, the steroid crystals aggregated with the antifoam agents. The aggregation resulted in a decrease of total mass transter area of substrate particles which is proportional to the dissolution rate of the solid substrate, and it consequently led to a significant decrease of the bioconversion rate. The bioconversion with neolin proceeded more slowly than with silicone oil. Increase of the concentration of the antifoam agents also yielded a significant decrease of the bioconversion rate.

• Journal of Microbiology and Biotechnology
• /
• v.28 no.3
• /
• pp.439-447
• /
• 2018

The aromatic compound p-hydroxybenzoate (PHBA) is an important material with multiple applications, including as a building block of liquid crystal polymers in chemical industries. The cytochrome P450 (CYP) enzymes are beneficial monooxygenases for the synthesis of chemicals, and CYP53A15 from fungus Cochliobolus lunatus is capable of executing the hydroxylation from benzoate to PHBA. Here, we constructed a system for the bioconversion of benzoate to PHBA in Escherichia coli cells coexpressing CYP53A15 and human NADPH-P450 oxidoreductase (CPR) genes as a redox partner. For suitable coexpression of CYP53A15 and CPR, we originally constructed five plasmids in which we replaced the N-terminal transmembrane region of CYP53A15 with a portion of the N-terminus of various mammalian P450s. PHBA productivity was the greatest when CYP53A15 expression was induced at $20^{\circ}C$ in $2{\times}YT$ medium in host E. coli strain ${\Delta}gcvR$ transformed with an N-terminal transmembrane region of rabbit CYP2C3. By optimizing each reaction condition (reaction temperature, substrate concentration, reaction time, and E. coli cell concentration), we achieved 90% whole-cell conversion of benzoate. Our data demonstrate that the described novel E. coli bioconversion system is a more efficient tool for PHBA production from benzoate than the previously described yeast system.

• Korean Journal of Food Science and Technology
• /
• v.49 no.1
• /
• pp.28-34
• /
• 2017

Biocatalytic modification of natural resources can be used to generate novel compounds with specific properties, such as higher viscosity and reactivity. The production of hydroxy fatty acids (HFAs), originally found in low quantities in plants, is a good example of the biocatalytic modification of natural vegetable oils. HFAs show high potential for application in a wide range of industrial products, including resins, waxes, nylons, plastics, lubricants, cosmetics, and additives in coatings and paintings. In a recent study, Pseudomonas aeruginosa strain PR3 was used to produce 7,10-dihydroxy-8(E)-octadecenoic acid (DOD) from oleic acid. This present study focused primarily on the utilization of three natural nut oils obtained from the Philippines -pili nut oil (PNO), palm oil (PO), and virgin coconut oil (VCO)- to produce DOD by P. aeruginosa strain PR3. Strain PR3 produced DOD from PNO and PO only, with PNO being the more efficient substrate. An optimization study to achieve the maximum DOD yield from PNO revealed the optimal incubation time and medium pH to be 48 h and 8.0, respectively. Among the carbon sources tested, fructose was the most efficiently used, with a maximum DOD production of 130 mg/50 mL culture. Urea was the optimal nitrogen source, with a maximum product yield of 165 mg/50 mL culture. The results from this study demonstrated that PNO could be used as an efficient substrate for DOD production by microbial bioconversion.

• Journal of Microbiology and Biotechnology
• /
• v.27 no.1
• /
• pp.77-83
• /
• 2017

Lignocellulosic biomass represents a potentially large resource to supply the world's fuel and chemical feedstocks. Enzymatic bioconversion of this substrate offers a reliable strategy for accessing this material under mild reaction conditions. Owing to the complex nature of lignocellulose, many different enzymatic activities are required to function in concert to perform efficient transformation. In nature, large multienzyme complexes are known to effectively hydrolyze lignocellulose into constituent monomeric sugars. We created artificial complexes of enzymes, called rosettazymes, in order to hydrolyze glucuronoxylan, a common lignocellulose component, into its cognate sugar ${\small{D}}$-xylose and then further convert the ${\small{D}}$-xylose into ${\small{D}}$-xylonic acid, a Department of Energy top-30 platform chemical. Four different types of enzymes (endoxylanase, ${\alpha}$-glucuronidase, ${\beta}$-xylosidase, and xylose dehydrogenase) were incorporated into the artificial complexes. We demonstrated that tethering our enzymes in a complex resulted in significantly more activity (up to 71%) than the same amount of enzymes free in solution. We also determined that varying the enzyme composition affected the level of complex-related activity enhancement as well as overall yield.

• Journal of Microbiology and Biotechnology
• /
• v.33 no.1
• /
• pp.1-14
• /
• 2023

Polyethylene terephthalate (PET) is a plastic material commonly applied to beverage packaging used in everyday life. Owing to PET's versatility and ease of use, its consumption has continuously increased, resulting in considerable waste generation. Several physical and chemical recycling processes have been developed to address this problem. Recently, biological upcycling is being actively studied and has come to be regarded as a powerful technology for overcoming the economic issues associated with conventional recycling methods. For upcycling, PET should be degraded into small molecules, such as terephthalic acid and ethylene glycol, which are utilized as substrates for bioconversion, through various degradation processes, including gasification, pyrolysis, and chemical/biological depolymerization. Furthermore, biological upcycling methods have been applied to biosynthesize value-added chemicals, such as adipic acid, muconic acid, catechol, vanillin, and glycolic acid. In this review, we introduce and discuss various degradation methods that yield substrates for bioconversion and biological upcycling processes to produce value-added biochemicals. These technologies encourage a circular economy, which reduces the amount of waste released into the environment.

• Journal of Microbiology and Biotechnology
• /
• v.12 no.3
• /
• pp.518-521
• /
• 2002

Poly(3-hydroxyalkanoate) copolyesters containing both carbon-carbon double and carbon-carbon triple bonds were produced by Pseudomonas oleovorans grown in mixtures of 10-undecynoic acid (10-UND($\equiv$)) and 10-undecenoic acid (10-UND(=)). The PHA content in the dry cells was usually 40 wt%. The bioconversion yield of ($10-UND({\equiv})$) to PHA by P. oleovorans was remarkably enhanced from 1% to over 24% as the fraction of 10-UND(=) in the carbon substrate mixtures increased from 0 to 50%. These values were higher than those obtained when P. oleovorans was grown in the same molar mixtures of ($10-UND({\equiv})$) and nonanoic acid (NA), indicating that 10-UND(=) was more efficient than NA as a cosubstrate in inducing cometabolic PHA production.

• Microbiology and Biotechnology Letters
• /
• v.16 no.3
• /
• pp.187-192
• /
• 1988

Production of 4-androstene-3,17-dione(AD) from cholesterol by microbial conversion was investigated. To facilitate the solubilization of cholesterol in the fermentation broth, ethanol was used as an organic solvent. Inhibition on cell growth by ethanol was observed to be negligible upto 2% (V/V) concentration. Microbial conversion was successfully carried out with high yield when the cholesterol was added at early logarithmic growth phase with pH control at 7.0. In order to improve the process productivity, bioconversion was conducted at various mode of cholesterol addition ; 0.1% (V/W) of cholesterol was found to be most appropriate for solubilization in ethanol and was added intermittently. When added three time(total 3 g/$\ell$), overall bioconversion yield reached upto 65% while single addition of same amount of cholesterol (3 g/$\ell$) yielded about 40% conversion.

• 한국생물공학회:학술대회논문집
• /
• 2001.11a
• /
• pp.529-532
• /
• 2001

Korean food waste, one of the abundantly available but environmentally problematic organic wastes in Korea, was utilized as solid-substrate by fungal strain Aspergillus niger ATcC 6275 for the production of enzymemixture containing amylase, cellulase and xylanase. The enzyme mixture can be used as high value-added animal feed. Solid-state fermentation method yielded a 84-fold enhancement in xylanase activity compared with submerged fermentation method. The effect of incubation period, incubation temperature, pH of medium, moisture content, inoculum size and enrichment of the medium with nitrogen and carbon sources were observed for optimal production of these enzymes The optimal amylase activity of 33.10 U/g, cellulase activity of 24.41 U/g, xylanase activity of 328.84 U/g were obtained at 8 days incubation with 50%(w/w) soy bean flake, with incubation temperature of $25^{\circ}C$, pH of 6.38, optimal moisture content of 55% and with inoculum size of $3.8{\times}10^6$spore/g. Enzyme activities were enhanced when ImM $CaSO_4$, 2% Malt extract and 2% galactose were added as mineral, nitrogen and carbon enrichment respectively.