• KSBB Journal
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• v.16 no.1
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• pp.87-94
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• 2001

The biosynthesis of Lovastatin, a cholesterol lowering agent formed by the filamentous fungus, cerulenin-resistant Aspergillus terreus mutant was studied in shake flasks and bioreactors. The lovastatin production could be improved by fed-batch under the limited condition of carbon source. The relationship between the fungal morphology and the lovastatin production was also examined during the fed-batch cultures. The fed-batch studies in shake flasks were carried out to find the optimum glucose feeding method, and the pulsed feeding of glucose from 3 days onward at 24 hours intervals was found to be optimal to increase the lovastatin production and reduce the average pellet size. When the pH was controlled at around 5.8 during the whole fermentation period, the lovastatin concentration reached 384 mg/L, which is much higher than the values obtained pH-uncontrolled and pH 7.4. The optimal glucose feeding strategies was found that 30 g/L of glucose was added initially in batch mode, and then fed-batch was conducted by continuous addition of glucose solution(180 g/L) from 72 to 240 hr at a rate of 1.2 mL/hr at $28^{\circ}C$, pH 5.8, 400 rpm, and 1.0 vvm. The lovastatin concentration of 547 mg/L was obtained in 168 hr. It was about 1.5 times higher than the value of the batch fermentation.

• Applied Biological Chemistry
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• v.40 no.6
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• pp.593-596
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• 1997

In the course of search antagonistic fungi from soil in green house, four kind of fungi (AF1, AF2, AF3, AF4) were isolated, which have activities against Phytophthora capsici, Botrytis cinera, Rhizoctonia solani, Pythium ultimum and Fusarium oxysporum. The AF2 was identified according to the morphological description of Aspergillus terreus. This antagonistic fungus inhibiting various plant pathogens was effective to reduce disease incidence of cucumber seedlings caused by mixed inoculum of Rhizoctonia solani, Pythium ultimum and Fusarium oxysporum. Antifungal compound I was isolated and purified by fresh chromatography from A. terreus. The $^1H$ and $^{13}C$ assignment of compound I was achieved from two-dimensional $^1H-^1H\;COSY$, HMQC, HMBC with the add of homonuclear and heteronuclear double resonance experiment. The compound I was identified butyrolactone I (${\alpha}$-oxo-${\beta}$-(p-hydroxyphenyl)-${\gamma}$-(p-hydroxy-m-3,3-dimethyl-allylbenzyl)-${\gamma}$-methoxycarbonyl-${\gamma}$-butyrolactone, $C_{24}H_{24}O_7$, M.W.=424).

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.228-231
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• 2002

Itaconic acid has been produced during the cutivation of Aspergillus terreus DSMZ 5770 by using several starchs as carbon sources. The starchs were pretreated by partial hydrolysis with some acids at various pH conditions. The highest yield for the production of itaconic acid has been found when rice starch was pretreated by sulfonic acid at pH 2.5 and utilized for the cultivation. Using the results from shaker fermentation A. terreus has been cultivated in 2.5 L bioreactor for the production of itaconic acid and its on-line monitoring.

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.263-267
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• 2003

Solid-state fermentation of lovastatin by Aspergillus terreus was investigated using commercially available 1.2 L polypropylene bottle designed for mushroom cultivation. Moist solid raw materials such as com, rice, and soy bean were tested and com was found to be most suitable for an economical production of lovastatin. 50% or higher water addition prior to the sterilization of com was effective for the maximal lovastatin production. About 0.5% (w/w) lovastatin content in dried cells and corn mass was obtained after 20 days of solid-state fermentation at 30$^{\circ}C$. For safety concerns, aflatoxin Bl and citrinin levels after fermentation were assayed but they were not detected. Lovastatin containing cells and corn residue after fermentation were autoclaved, dried, crushed, and fed to chicken for a period of 3 weeks. Approximately 20% reduction of blood cholesterol level of chicken was observed.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 2000.10a
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• pp.178-180
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• 2000

• Journal of Microbiology and Biotechnology
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• v.27 no.1
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• pp.101-111
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• 2017

The task of improving a fungal strain is highly time-consuming due to the requirement of a large number of flasks in order to obtain a library with enough diversity. In addition, fermentations (particularly those for fungal cells) are typically performed in high-volume (100-250 ml) shake-flasks. In this study, for large and rapid screening of itaconic acid (IA) high-yielding mutants of Aspergillus terreus, a miniaturized culture method was developed using 12-well and 24-well microtiter plates (MTPs, working volume = 1-2 ml). These miniaturized MTP fermentations were successful, only when highly filamentous forms were induced in the growth cultures. Under these conditions, loose-pelleted morphologies of optimum sizes (less than 0.5 mm in diameter) were casually induced in the MTP production cultures, which turned out to be the prerequisite for the active IA biosynthesis by the mutated strains in the miniaturized fermentations. Another crucial factor for successful MTP fermentation was to supply an optimal amount of dissolved oxygen into the fermentation broth through increasing the agitation speed (240 rpm) and reducing the working volume (1 ml) of each 24-well microtiter plate. Notably, almost identical fermentation physiologies resulted in the 250 ml shake-flasks, as well as in the 12-well and 24-well MTP cultures conducted under the respective optimum conditions, as expressed in terms of the distribution of IA productivity of each mutant. These results reveal that MTP cultures could be considered as viable alternatives for the labor-intensive shake-flask fermentations even for filamentous fungal cells, leading to the rapid development of IA high-yield mutant strains.

• Journal of Microbiology and Biotechnology
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• v.23 no.10
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• pp.1445-1453
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• 2013

The scale-up criterion of constant oxygen mass transfer coefficient ($k_La$) was applied for the production of itaconic acid (IA) in a 50 L pilot-scale fermentor by the fungal cells of Aspergillus terreus. Various operating conditions were examined to collect as many $k_La$ data as possible by adjusting the stirring speed and aeration rate in both 5 L and 50 L fermentor systems. In the fermentations performed with the 5 L fermentor, the highest IA production was obtained under the operating conditions of 200 rpm and 1.5 vvm. Accordingly, we intended to find out parallel agitation and aeration rates in the 50 L fermentor system, under which the $k_La$ value measured was almost identical to that ($0.02sec^{-1}$) of the 5 L system. The conditions of 180 rpm and 0.5 vvm in the 50 L system turned out to be optimal for providing almost the same volumetric amount of dissolved oxygen (DO) into the fermentor, without causing shear damage to the producing cells due to excessive agitation. Practically identical fermentation physiologies were observed in both fermentations performed under those respective operating conditions, as demonstrated by nearly the same values of volumetric ($Q_p$) and specific ($q_p$) IA production rates, IA production yield ($Y_{p/s}$), and specific growth rate (${\mu}$). Specifically, the negligible difference of the specific growth rate (${\mu}$) between the two cultures (i.e., $0.029h^{-1}$ vs. $0.031h^{-1}$) was notable, considering the fact that ${\mu}$ normally has a significant influence on $q_p$ in the biosynthesis of secondary metabolites such as itaconic acid.

• Journal of Microbiology and Biotechnology
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• v.21 no.9
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• pp.947-953
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• 2011

A fungal strain, Aspergillus terreus strain GA2, isolated from an agricultural field cultivating sweet sorghum, produced feruloyl esterase using maize bran. In order to obtain maximum yields of feruloyl esterase, the solid state fermentation (SSF) conditions for enzyme production were standardized. Effective feruloyl esterase production was observed with maize bran as substrate followed by wheat bran, coconut husk, and rice husk among the tested agro-waste crop residues. Optimum particle size of 0.71-0.3 mm and moisture content of 80% favored enzyme production. Moreover, optimum feruloyl esterase production was observed at pH 6.0 and a temperature of $30^{\circ}C$. Supplementation of potato starch (0.6%) as the carbon source and casein (1%) as the nitrogen source favored enzyme production. Furthermore, the culture produced the enzyme after 7 days of incubation when the C:N ratio was 5. Optimization of the SSF conditions revealed that maximum enzyme activity (1,162 U/gds) was observed after 7 days in a production medium of 80% moisture content and pH 6.0 containing 16 g maize bran [25% (w/v)] of particle size of 0.71-0.3 mm, 0.6% potato starch, 3.0% casein, and 64 ml of formulated basal salt solution. Overall, the enzyme production was enhanced by 3.2-fold as compared with un-optimized conditions.

• Journal of Microbiology and Biotechnology
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• v.27 no.2
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• pp.306-315
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• 2017

Metabolic engineering with a high-yielding mutant, A. terreus AN37, was performed to enhance the production of itaconic acid (IA). Reportedly, the gene cluster for IA biosynthesis is composed of four genes: reg (regulator), mtt (mitochondrial transporter), cad (cis-aconitate decarboxylase), and mfs (membrane transporter). By overexpressing each gene of the IA gene cluster in A. terreus AN37 transformed by the restriction enzyme-mediated integration method, several transformants showing high productivity of IA were successfully obtained. One of the AN37/cad transformants could produce a very high amount of IA (75 g/l) in shake-flask cultivations, showing an average of 5% higher IA titer compared with the high-yielding control strain. Notably, in the case of the mfs transformants, a maximal increase of 18.3% in IA production was observed relative to the control strain under the identical fermentation conditions. Meanwhile, the overexpression of reg and mtt genes showed no significant improvements in IA production. In summary, the overexpressed cis-aconitate decarboxylase (CAD) and putative membrane transporter (MFS) appeared to have positive influences on the enhanced IA productivity of the respective transformant. The maximal increases of 13.6~18.3% in IA productivity of the transformed strains should be noted, since the parallel mother strain used in this study is indeed a very high-performance mutant that has been obtained through intensive rational screening programs in our laboratory.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.5
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• pp.666-670
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• 2008

Lovastatin (Mevinolin, Monacolin K) is a well-known drug for the therapy of hypercholesterolemia. It is an important fungal secondary metabolite as it inhibits 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMG-CoA reductase, EC 1.1.1.34) which catalyzes a major rate-limiting step in the biosynthesis of cholesterol. Both soybeans and black soybeans with Aspergillus terreus ATCC 20542 mutant were used as the seed culture for the mass production of lovastatin. The production of lovastatin in soybean seed culture of Asp. terreus was twofold compared to that of black soybean seed culture. The effect of two different vessels (petri dish and Erlenmeyer flask) on lovastatin production was also studied. The production of lovastatin on petri dish was tenfold to that of Erlenmeyer flask. Furthermore, the most lovastatin production on rice bran was achieved when the soybean seed culture was treated by heat shock at $30^{\circ}C$ for 1 hour, representing 82% of HMG-CoA reductase inhibition in the koji extract. We estimated that the heat treated soybean seed culture could be a new method for the mass production of lovastatin.