• Mycobiology
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• v.33 no.4
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• pp.223-229
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• 2005

A novel fungal strain Aspergillus sp. L117 that produced acid-stable and thermostable phytase was isolated on basis of the clearing zone on PSM plate and the ability of Na-phytate hydrolysis. The phytase of isolate showed a 3-fold higher activity than that of A. ficuun NRRL3135. The Aspergillus sp. L117 produced maximal level of phytase at initial pH of 5.0 and $30^{\circ}C$. The optimal pH and temperature for phytase activity were 5.5 and $50^{\circ}C$, respectively. The phytase showed totally stable activity after 20 min of exposure between 30 and $90^{\circ}C$, and even at $100^{\circ}C$. The highest level of residual phytase activity was obtained at pH 5.5, and still retained the stability at the broadest pH ranges (2.0 to 7.0) of all the aforementioned phytases. Storage stability of phytase was preserved over 96% of initial activities for 60 days at 4, -20, and $-70^{\circ}C$ and to retain even 70% of the initial activity at room temperature.

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.1
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• pp.38-45
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• 1998

To extract insoluble proteins and to improve funtional properties of abolished proteins, an phytase producing Aspergillus sp. SM-15 was isolated from soil. The enzyme was purified and its enzymological characteristics were investigated. Phytase production reached to maximum when the wheat bran medium containing 1% mannose, 1% yeast extract, 1% (NH4)2HPO4 and 0.2% calcium chloride was cultured for 4 days. Phytase was purified 17.1 fold and specific activity was 244.32unit/mg by a sequencial process of ammonium sulfate fraction, ion exchange chromatography and gel filtrations Pruified enzyme was confirmed as a single band by the polyacrylamide gel electro-phoresis. The molecular weight of phytase was estimated to be 46,000. The optimum pH and temperature for the phytase activity were 5.5 and 5$0^{\circ}C$. The enzyme is stable in pH 4.5~5.5, 6$0^{\circ}C$. The activity of purified enzyme was inhibited by Hg2+ whereas activited by Pb2+ and Fe2+. The activity of phytase was inhibited by the treatment with iodine. The result indicate the possible involvement of histidine at active site. Km and Vmax of the puridied phytase were 37.037mM/L and 159.87umol/min, respectively.

• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.1
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• pp.57-63
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• 2000

To extract insoluble proteins from abolished soybean meal, the meal was treatesd with phytase and protease produced by Aspergillus sp. SM-15 and Aspergillus sp. MS-18. The extraction of insoluble soybean protein was increased at alkaline range more than pH 5 in case of phytase, pH 7 to 11 in case of protease and pH 5 to 12 in case of the mixed enzyme of phytase and protease. The optimum extraction temperature of insoluble protein was 5$0^{\circ}C$ for phytase and the mixed enzyme of phytase and protease, and 6$0^{\circ}C$ for protease. The optimum treatment time for extraction of protein was 9 hrs for phytase, 11 hrs for protease and the mixed enzyme of phytase and protease and optimum unit of enzyme for extraction of protein was 600 unit, 40 unit and 900 unit＋60 unit in case of phytase, protease, phytase and protease, respectively. The treatment of mixed enzyme showed higher extracton rate of protein than single enzyme treatment. The foaming capacity, foaming stability, emulsion capacity, and emulsion stability of soybean meal protein by the treatment of the enzymes increased at all pH range. Further more oil absorption as well as water absorption capacities by the treatment of the enzymes were also increased. The functional properteis of the soybean meal protein treated by the mixed enzyme were higher than those of soybean meal protein treated by the single enzyme.

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.1
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• pp.46-50
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• 1998

This study was peformed to improve extraction of insoluble proteins and to evaluate funtional properties of abolished proteins by the phytase produced by Asporgillus sp. The optimum pH, temperature, treatment time and unit of the enzyme for extraction of protein were pH 4.0~5.0, $50^{\circ}C$, 8~10 hrs and 120 units. The foaming capacity and foaming stability of sesame meal protein after enzyme treatment were virtually unchanged as compared to control. The emulsion capacity and emulsion stability of sesame meal protein was higher than control. Oil absorption as well as water absorption capacities of sesame meal protein were higher than control.

• Microbiology and Biotechnology Letters
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• v.10 no.2
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• pp.133-144
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• 1982

The distribution of acid phosphatase activity was investigated with 141 microorganisms from the type culture collection of Chong Kun Dang laboratory and the 41 strains isolated from natural sources. The phytase activity was detected mainly with fungal strains. A fungus isolated from soil and identified as Aspergillus niger had shown the highest phytase activity. The environmental conditions for the enzyme formation by the isolate and some properties of the enzyme were also studied. The results obtained were as follows: (1) The highest phytase production was observed when the fungus was cultivated at 28$^{\circ}C$ for 5 days in the corn starch based medium using the cells incubated at 34$^{\circ}C$ for 3 days as a seed. (2) The optimal initial pH of the culture medium was found to around 2 for the formation of phytase. (3) Sucrose was proved to be one of the most effective carbon sources tested for the enzyme production. (4) As an inorganic nitrogen source, potassium nitrate was found to give a good result in the production of phytase. (5) Synthesis of phytase was significantly increased by the supplement with 0.2 % corn steep liquor to the basal medium as an organic nitrogen source. (6) At the concentration of 40-80 mg inorganic phosphate per liter of the culture medium, the enzyme formation revealed the highest level. But as the phosphate was increased above this optimum concentration the phytase activity was drastically decreased although the cell density showed to be still increasing

• Korean Journal of Food Science and Technology
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• v.30 no.4
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• pp.895-901
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• 1998

To extract insoluble proteins and improve functional properties of sesame meal proteins was treated with phytase and protease from Aspergillus sp. It was found that the optimum pH, optimum temperature, optimum treatment time and optimum unit of enzyme for extraction of protein were pH $10{\sim}12$ (alkaline), $60^{\circ}C$, 11 hr. and 900 units of phytase and 60 units of protease, respectively. The foaming capacity, foaming stability, oil absorption and water absorption of sesame meal protein after treatment with phytase and protease were increased as compared to the control.

• Fisheries and Aquatic Sciences
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• v.7 no.2
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• pp.51-57
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• 2004

Total phosphorus contents in rice bran and soybean meal were determined to be 5.81 and $2.77\%$, respectively, and $97.2\%$ of phosphorus in rice bran and $66.4\%$ in soybean meal were presented as phytate phosphorus. Optimum pH condition for hydrolysis of phytate in rice bran and soybean was determined to be in the pH range of 3.7 and 5.3. The highest activity of phytase for hydrolysis of phytate in both samples was determined to be at $55^{\circ}C$ for rice bran and $55-60^{\circ}C$ for soybean. Hydrolysis of phytate in soybean meal at pH 5.0 increased with the co-reaction or consecutive reaction with protease; however, in rice bran hydrolysis decreased with co-reaction with protease. Phytate degradation of soybean meal in the presence of pepsin at pH 2.5 showed higher than that of rice bran. Phytate degradation of rice bran in the presence of trypsin or pancreatin at pH 7.0 increased the activity around 2-times compared with the activity in the absence of trypsin or pancreatin. The results of this study suggest that hydrolysis of phytate in rice bran or soybean meal with phytase and protease may provide an alternative process for the preparation of aquacultural feed with a low level of organic phosphorus.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.05a
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• pp.220-221
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• 2001

Phytic acid (myo-inositol 1,2,3,4,5,6-hexakisdihydrogen phosphate) is one of the major storage form of phosphorous in the seeds of plants, which are the principal components of feed stuffs. Monogastric animals like Pigs and poultry as well as fish lack phytase activities in their digestive system and most undigested phytic acid was excreted in their manure. (omitted)