• Biotechnology and Bioprocess Engineering:BBE
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• 제11권6호
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• pp.522-525
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• 2006

Biodiesel conversion from soybean oil reached a maximum of 70% at 18 h using immobilized 1,3-specific Rhizopus oryzae lipase alone. Biodiesel conversion failed to reach 20% after 30 h when immobilized nonspecific Candida rugosa lipase alone was used. To increase the biodiesel production yield, a mixture of immobilized 1,3-specific R. oryzae lipase and nonspecific C. rugosa lipase was used. Using this mixture a conversion of greater than 99% at 21 h was attained. When the stability of the immobilized lipases mixture was tested, biodiesel conversion was maintained at over 80% of its original conversion after 10 cycles.

• Journal of Microbiology and Biotechnology
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• 제18권12호
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• pp.1927-1931
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• 2008

In this study, the enzymatic process for biodiesel production was optimized using a mixture of immobilized Rhizopus oryzae and Candida rugosa lipases. The optimal temperature and agitation speed for biodiesel production were $45^{\circ}C$ and 300 rpm, respectively. The optimal ratio of R. oryzae and C. rugosa lipases in the mixture was 3:1 (w:w). When 3 mmol of methanol was the initial reaction medium and 3 mmol of methanol was added every 1.5 h during biodiesel production, biodiesel conversion was over 98% at 4 h. In addition, when the immobilized lipase mixture was reused, biodiesel conversion exceeded 80% after 5 reuses.

• Journal of Microbiology and Biotechnology
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• 제27권2호
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• pp.277-288
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• 2017

Rhizomucor miehei NRRL 5282 and Rhizopus oryzae NRRL 1526 can produce lipases with high synthetic activities in wheat bran-based solid-state culture. In this study, the purification and biochemical characterization of the lipolytic activities of these lipases are presented. SDS-PAGE indicated a molecular mass of about 55 and 35 kDa for the purified R. miehei and Rh. oryzae enzymes, respectively. p-Nitrophenyl palmitate (pNPP) hydrolysis was maximal at $40^{\circ}C$ and pH 7.0 for the R. miehei lipase, and at $30^{\circ}C$ and pH 5.2 for the Rh. oryzae enzyme. The enzymes showed almost equal affinity to pNPP, but the $V_{max}$ of the Rh. oryzae lipase was about 1.13 times higher than that determined for R. miehei using the same substrate. For both enzymes, a dramatic loss of activity was observed in the presence of 5 mM $Hg^{2+}$, $Zn^{2+}$, or $Mn^{2+}$, 10 mM N-bromosuccinimide or sodium dodecyl sulfate, and 5-10% (v/v) of hexanol or butanol. At the same time, they proved to be extraordinarily stable in the presence of n-hexane, cyclohexane, n-heptane, and isooctane. Moreover, isopentanol up to 10% (v/v) and propionic acid in 1 mM concentrations increased the pNPP hydrolyzing activity of R. miehei lipase. Both enzymes had 1,3-regioselectivity, and efficiently hydrolyzed p-nitrophenyl (pNP) esters with C8-C16 acids, exhibiting maximum activity towards pNP-caprylate (R. miehei) and pNP-dodecanoate (Rh. oryzae). The purified lipases are promising candidates for various biotechnological applications.

• Journal of Microbiology and Biotechnology
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• 제17권4호
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• pp.650-654
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• 2007

In our previous work, a method of pretreating lipase was developed to prevent loss of its activity during covalent immobilization. In this study, Rhizopus oryzae lipase was pretreated before immobilization and then immobilized on a silica gel surface. The effects of the various materials and conditions used in the pretreatment stage on the activity of immobilized lipase were investigated. Immobilized lipase pretreated with 0.1% of soybean oil had better activity than those pretreated with other materials. The optimal temperature, agitation speed, and pretreating time for lipase pretreatment were determined to be $40^{\circ}C$, 200rpm, and 45min, respectively. The activity of immobilized soybean oil pretreated lipase was 630U/g matrix, which is 20 times higher than that of immobilized non-pretreated lipase. In addition, immobilized lipase activity was maintained at levels exceeding 90% of its original activity after 10 reuses.

• 한국식품과학회지
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• 제31권1호
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• pp.176-182
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• 1999

콩알메주 발효의 pilot system에 M. circinlloides, M. hiemalis, R. oryzae, R. stolonifer를 각각 접종하여 45시간 발효시킨 후 메주의 효소활성, 영양성분, 향기 성분 등을 분석하고 발효된 메주로 한식간장을 제조하여 제품의 관능을 평가하였다. 메주의 pH는 $7.16{\sim}8.38$, 환원당은 $0.54{\sim}2.64%$, 아미노태질소는 $93{\sim}312\;mg%$, 유리지방산은 $0.06{\sim}2.00%$의 수준이었으며 아미노산, 유리당, 지방산, 유기산의 분석 결과, 각 균주에 따라 특징적인 구성비를 보여주었다. Amylase 활성과 당류의 분해도는 R. oryzae가, protease 활성은 R. stolonifer가 가장 높았으며 lipase 활성과 지질의 분해도는 각 균주별로 큰 차이를 보이지 않았다. 메주의 향기 성분 분석 결과 Mucor속 균주들은 Aspergillus와 비슷한 향기성분을 생산하는 것으로 조사되었고 Rhizopus속 균주들은 Bacillus의 특징적인 향기성분으로 알려진 benzaldehyde, pyrazine류 화합물과 함께 Aspergillus에서만 특징적으로 검출된 dl-limonene, 2,3-butanediol 등도 검출되어 Aspergillus와 Bacillus의 특성을 공유하는 것으로 조사되었다. 각 메주로 간장을 제조한 결과, M. hiemalis와 R. stolonifer 실험구가 좋은 관능평가를 보여 이 두 균주를 이용한 콩알메주로 한식간장을 제조할 수 있는 가능성을 제시하였다.

• Journal of Microbiology and Biotechnology
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• 제28권5호
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• pp.739-747
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• 2018

The low solubility and high-cost recovery of Propionibacterium acnes polyunsaturated fatty acid isomerase (PAI) are key problems in the bioproduction of high value-added conjugated linoleic acid (CLA). To improve the solubility of recombinant PAI, six chaperone proteins were coexpressed with PAI. Introduction of GroELS proteins dramatically improved the PAI solubility from 29% to 97%, with increased activity by 57.8%. Combined expression of DnaKJ-GrpE and GroELS proteins increased the activity by 11.9%. In contrast, coexpression of DnaKJ-GrpE proteins significantly reduced the activity by 57.4%. Plasmids pTf16 harboring the tig gene and pG-Tf2 containing the tig and groEL-groES genes had no visible impact on PAI expression. The lytic protein E was then introduced into the recombinant Escherichia coli to develop a cell autolysis system. A 35% activity of total intracellular PAI was released from the cytoplasm by suspending the lysed cells in distilled water. The PAI recovery was further improved to 81% by optimizing the release conditions. The lipase from Rhizopus oryzae was also expressed in E. coli, with an extracellular activity of 110.9 U/ml. By using the free PAI and lipase as catalysts, a joint system was established for producing CLA from sunflower oil. Under the optimized conditions, the maximum titer of t-10,c-12-CLA reached 9.4 g/l. This work provides an effective and low-cost strategy to improve the solubility and recovery of the recombinant intracellular PAI for further large-scale production of CLA.