• Korean Journal of Microbiology
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• v.31 no.3
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• pp.218-223
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• 1993

Conditions for the release and regeneration of protoplasts form Rhizopus oryzae and intergeneric protoplast fusion between Rhizopus oryzae and Aspergillus oryzae were studied. High yields of protoplast fusion between Rhizopus oryzae and Aspergillus oxyzae were studied. High yield of protoplasts from young germilings of R. oryzae were obtained by using lytic enzymes containing chitosanase (3 mg/ml), chitinase (3 mg/ml) and Novozym 234 (5 mg/ml). 0.5M glucose was used as the osmotic stabilizer and optimum pH of buffer was determined to be pH 7.5-8.0. Under these conditions, protoplasts were formed after about 3-4 hrs incubation. Approximately, 1.0%-4.9% of these protoplasts were formed after about 3-4 hrs incubation. Approximately, 1.0%-4.9% of these protoplasts regenerated on solid medium with a soft agar overlay. We have also carried out protoplasts fusion between R. oryzae and A. oryzae and have succeeded in obtaining three types of intergeneric fusants. In these experiments, 35% PEG-4000 and 10 mM CaCl$_{2}$ were used as fsogenic agents, and auxotrophic properties were used as a genetic marker to select fusants. Complementation frequency be protoplasts fusion of A. oxyzae and R. oryzae was 4.4% * 10$^{-5}$ . The fusant strains of the first type were prototrophs showing an Aspergillus type morphology with dark-yellow sporulation, those of the second type were also Apergillus type morphology but showed no sporulation. And the strains of the third type stopped growing when fusion products grown on regeneration minimal medium were transferred to fresh minimal medium. The formation of fusion products was observed by fluorescent vital stains for complementary labelling of protoplats from R. oryzae and A. oryzae. Rhodamine 6G and fluorescein diacetate wer useful complementary vital stains of Rhizopus and Aspergillus protoplasts for visualization of requency and type (dicell, multicell) of fusion.

• Food Science and Preservation
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• v.21 no.4
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• pp.573-580
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• 2014

The enzymatic activity of Nuruk and the quality properties of Yakju were investigated according to different fungi. The fungi that were used in this study were Aspergillus kawachii KCCM 32819, Aspergillus niger KCCM 32005, Rhizopus japonicus KCCM 11604, Rhizopus oryzae KCCM 11272, Rhizopus oryzae KCCM 11273, Rhizopus oryzae KCCM 11276, and Mucor rouxii KCCM 60148. The study results are as follows. The saccharogenic power of Rhizopus oryzae KCCM 11272 Nuruk was the highest (3,647.72 SP/g) among all the samples. The ${\alpha}$-amylase production and protease activities were highest (3.76 DU and 4.7 tyrosine mg/min, respectively) in the Rhizopus japonicus KCCM 11604 Nuruk. The pH levels of the Yakju made with commercial Nuruk and Rhizopus japonicus KCCM 11604 Nuruk were 4.14 and 4.07, respectively. The total titratable acid content of the Yakju made with Rhizopus oryzae KCCM 11273 Nuruk was the highest (0.56%) among all the samples. Rhizopus japonicus KCCM 11604 and Rhizopus oryzae KCCM 11272 had the highest ethanol yields (15.18% and 15.10%, respectively). In the sensory evaluation carried out in this study, the panel preferred the Yakju made with Rhizopus japonicus KCCM 11604 Nuruk. Overall, however, the panel did not like the Yakju made with Aspergillus niger KCCM 32005 Nuruk.

• Mycobiology
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• v.39 no.2
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• pp.140-142
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• 2011

Soft rot in apple caused by Rhizopus oryzae was found for the first time in Korea. A detailed description of the specimen is given along with its internal transcribed spacer rDNA sequence. The fungus was identified as Rhizopus oryzae based on the mycological characteristics, molecular data, and pathogenicity testing.

• Mycobiology
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• v.40 no.3
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• pp.214-216
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• 2012

Soft rot on banana fruit caused by Rhizopus oryzae was identified for the first time in Korea. Colonies were white to light brown and formed numerous sporangiospores. Optimum temperature for mycelial growth was $30^{\circ}C$. Sporangia were globose and $30{\sim}200{\mu}m$. Sporangiophores were usually straight, $8{\sim}20{\mu}m$, and rhizoids usually in groups of 3~5. Columella were globose to sub-globose and $90{\sim}110{\mu}m$. Sporangiospores were sub-globose or oval and $4{\sim}10{\mu}m$. Based on its mycological characteristics, molecular analysis, and pathogenicity to host plants, this fungus was identified as Rhizopus oryzae Went & Prisen Geerligs. This is the first report of soft rot on banana caused by Rhizopus oryzae in Korea.

• Mycobiology
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• v.38 no.4
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• pp.336-338
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• 2010

Rhizopus oryzae is reported for the first time on Cucumis melo L. var. makuwa Makino. A detailed description of this Korean specimen is given, along with its rDNA internal transcribed spacer sequence. On the basis of mycological characteristics and molecular data, the fungus was identified as R. oryzae Went & Prinsen Geerligs.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.2
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• pp.211-215
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• 2002

Pretense production and its characteristics were investigated for Rhizopus stolonifer, Rhizopus oryzae and Absidia corymbifera which were isolated from Korean traditional meju. The optimum culture conditions of the strains for the production of protease in basic medium [wheat bran : 1% glucose solution=1 : 1 (w/v)] were 3$0^{\circ}C$ and 4 days. The optimum pH and temperature for the enzyme activity of crude enzymes produced by Rhizopus sto-lonifer, Rhizopus oryzae and Absidia corymbifera were pH 6.0 and 5$0^{\circ}C$, respectively. The enzymes were relatively stable at pH 4.0~7.0, at temperature below 4$0^{\circ}C$, and at NaCl concentration lower than 16%. The $K_{m}$ value for Hammastein casein was 3.3$\times$10$^{-4}$ , 0.75$\times$10$^{-4}$ and 1.3$\times$10$^{-4}$ M, and $V_{max}$ value was 17.2$\mu\textrm{g}$/min, 9.4$\mu\textrm{g}$/min and 7.8$\mu\textrm{g}$/min, respectively.y.

• The Korean Journal of Food And Nutrition
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• v.8 no.1
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• pp.6-12
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• 1995

The purpose of this study was to examine the aptitude of wheat flour-Nuluks, for Takju brewing, which were made with Aspergillus oryzae, Rhizopus japonicus or Aspergillus usamii mut. Shirousamii, and to know the way of effective use the Aspergillus oryzae-Nuluk showed high saccharogenic activity, and Rhizopus japonicus-Nuluk high proteolytic activity. When these two Nuluks were combined, the activities of saccharogenic amylase and protease were more balanced. The Takju mash of Aspergillus oryzae-Nuluk was high in acidity and in amino acidity, and that of Rhizopus japonicus-Nuluk high in the content of free sugar, but, that of Aspergillus usamii mut. Shirousamii-Nuluk was low in amino acidity, free sugar and ethanol content. The Takju of Rhizopus japonicus-Nuluk was high in the content of suspended solid and slow in its sedimenting rate, but that of Aspergillus usamii mut. Shirousamii-Nuluk was not. The Takju which was made with combined use of Aspergillus oryzae-Nuluk and Rhizopus japonicus-Nuluk was more balanced in the composition of flavoring ingredients, and was slow in sedimenting rate of suspended solid. Moreover, it gained good result in sunsory evaluation test.

• Microbiology and Biotechnology Letters
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• v.44 no.3
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• pp.376-382
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• 2016

The amylolytic enzyme activities of nuruks collected or produced in this study were examined. A maximum α-amylase activity of 24,747.1 ± 777.7 units/mg protein was obtained for a nuruk incubated at a relative humidity of 40% at 30℃. A nuruk matured at a relative humidity of 50% at 25℃ showed the highest glucoamylase acitivity. Among the 98 fungal strains isolated from the nuruk exhibiting the highest amylolytic enzyme activities, 26 strains of Aspergillus oryzae and 18 strains of Rhizopus oryzae were identified. Rhizopus oryzae MBF345 showed an α-amylase activity of 36,724.9 ± 10.2 units/mg protein and a glucoamylase activity of 4,911.8 ± 48.1 SP. These values were 1.7-fold and 1.4-fold greater, respectively, than those of the control strain. Strain MBF345 was deposited as KCTC46312 in the Korean Culture Type Collection.

• Korean Journal of Microbiology
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• v.6 no.3
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• pp.100-105
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• 1968

As a taxonomical study of Rhizopus spp., 30 strains of Rhizopus spp. were isolated from 55 specimens of "Meju" which were collected through all over South-Korea. Results of the experiments with the 30 strains of Rhizopus spp. are as follows; 1. One strain of them was classified in to Rhizopus nigricans group. 2. Eleven strains of them were classified in to Rhizopus chinencis group. 3. Three strains of them were classified in to Rhizopus oryzae sub-group. 4. Fifteen strains of them were classified in to Rhizopus oryzae Japanicus sub-group. All these strains of Rhizopus spp. have not been reported yet, so far in South-Korea.uth-Korea.

• KSBB Journal
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• v.6 no.4
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• pp.403-406
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• 1991

Lactic acid production yield was examined for commercial use by immobilizing Rhizopus oryzae with radiation induced polymer. The supporting material was synthesized by the low temperature radiation polymerization method, in which the microorganism was entrapped physically by contacting together in culture broth shaking for 24 hours. Support polymers with 5∼10vol-% monomers were able to increase their catalytic activities, consuming 65g/1 of glucose, producing 56g/1 of lactic acid, thus yielding 88% of product in general. But in free culture, the microorganism consumed almost all carbon sources and produced lactic acid only 60% even after 96 hours. The yield of the experiment under discussion was significantly high compared with conventional immobilization procedure.