Microbial production and biotechnological applications of α-galactosidase

Characterization of a novel GH36 α-galactosidase from Bacillus megaterium and its application in degradation of raffinose family oligosaccharides.

A novel α-galactosidase of glycoside hydrolase family 36 was cloned from Bacillus coagulans, overexpressed in Escherichia coli, and characterized. The purified enzyme Aga-BC7050 was 85 kDa according to SDS-PAGE and 168 kDa according to gel filtration, indicating that its native structure is a dimer. With p-nitrophenyl-α-d- galactopyranoside (pNPGal) as the substrate, optimal temperature and pH were 55 °C and 6.0, respectively. At 60 °C for 30 min, it retained > 50% of its activity. It was stable at pH 5.0-10.0, and showed remarkable resistance to proteinase K, subtilisin A, α-chymotrypsin, and trypsin. Its activity was not inhibited by glucose, sucrose, xylose, or fructose, but was slightly inhibited at galactose concentrations up to 100 mM. Aga-BC7050 was highly active toward pNPGal, melibiose, raffinose, and stachyose. It completely hydrolyzed melibiose, raffinose, and stachyose in < 30 min. These characteristics suggest that Aga-BC7050 could be used in feed and food industries and sugar processing.

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A novel α-galactosidase from the thermophilic probiotic Bacillus coagulans with remarkable protease-resistance and high hydrolytic activity.

Biochemical characterization of a novel β-galactosidase from Paenibacillus barengoltzii suitable for lactose hydrolysis and galactooligosaccharides synthesis

Characterization of a high performance α-galactosidase from Irpex lacteus and its usage in removal of raffinose family oligosaccharides from soymilk.

A protease-resistant α-galactosidase from Pleurotus djamor with broad pH stability and good hydrolytic activity toward raffinose family oligosaccharides

A protease-resistant α-galactosidase from Pleurotus citrinopileatus with broad substrate specificity and good hydrolytic activity on raffinose family oligosaccharides

The invention discloses an application of boletus edulis in reducing the nitrite content in fermented food or pickled food. Experiments testify that if boletus edulis is fermented together with common pickle ingredients, the nitrite content in the pickle ingredients can be reduced remarkably, wherein the boletus edulis and the common pickle ingredients are fermented for 4 days with the mass ratio of 1.4 to 1, and compared with the common pickle ingredients which are fermented individually, the nitrite content can be reduced by 97 percent. According to the invention, fermenting food or pickling food with the boletus edulis is low in cost, simple in process, and the quality and safety of fermented products are excellent. If putting the boletus edulis into the pickle processing and other food processing industries is carried out, the boletus edulis can play a positive role both in the continuous development of the industry and the improvement of market competitiveness of the product.

Application of boletus edulis in reducing nitrite content in fermented food or pickled food

The invention discloses a matsutake polypeptide and a matsutake extract, and application thereof. The polypeptide disclosed by the invention is derived from matsutake and named matsutake polypeptide, which is disclosed as Sequence 1 in the sequence table. The matsutake extract containing the matsutake polypeptide also belongs to the protection range of the invention. The preparation method of the matsutake extract comprises the following steps: (1) adding matsutake sporophores into water, homogenizing, and extracting; and (2) after finishing the step (1), centrifuging and collecting the supernatant. The polypeptide disclosed by the invention is derived from food, thereby enriching the hypotensive drug screening library and providing theoretical references for further development of matsutake. The matsutake polypeptide and matsutake extract have significant application value for treating hypertension.

Hu Yujing

Papers

A protease-resistant α-galactosidase from Pleurotus djamor with broad pH stability and good hydrolytic activity toward raffinose family oligosaccharides

A protease-resistant α-galactosidase from Pleurotus citrinopileatus with broad substrate specificity and good hydrolytic activity on raffinose family oligosaccharides

Application of boletus edulis in reducing nitrite content in fermented food or pickled food

Matsutake polypeptide and matsutake extract, and application thereof