脱脂大豆からの蛋白質抽出率に対するIrpex lacteus培養濾液の影響

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About half of the protein in defatted soy bean can be usually extracted with hot water, but the remaining is difficult it extract by this procedure. In a previous investigation, a high yield of protein was attained by treating these soy bean materials with cellulase preparations from Trichoderma viride. A similar attempt was made, using other enzyme preparations from a wood-rotting fungus, Irpex lacteus (Polyporus tulipiferae) which is known to produce a good deal of cellulase and hemicellulase.Promising results were obtained as to the extraction of protein by using culture filtrates of the fungus, but no conclusive evidence for the correlation between the yield of protein and the cellulase activity was found. Attention was, therefore, paid to estabilish what sorts of enzyme mainly participate in the extraction of protain.Since cellulase and hemicellulase are commonly assumed to be adaptive enzymes, the fungus was cultured on several substrates, such as malt, bran, cotton, defatted soy bean and soy bean hull, which contain cellulose or hemicellulose or both. Proteiase activities in the culture filtrates were also measured in addition to the activities of cellulase and hemicellulase.Among the culture filtrates, cotton-culture showed an extremely high level of cellulase activity, and the cultures of bran and soy bean hull were considerably rich in himicellulase activity. Each culture filtrate was added to the residue of defatted soy bean, which had been obtained by pretreatment with hot water. After a few day incubataion at 30°, a net increase in total and amino-nitrogens in the incubation mixtures was determined by the Micro-Kjeldahl and van Slyke methods, respectively.It was found that 78.7% of the insoluble part of nitrogen in the residue was extracted by the bran-cluture, 58.6% by the soy bean hull-culture, 24.1% by the defatted soy bean-culture, 27.6% the cotton-culture. The extraction rate appeared to be approximately parallel with the activity of protease in each filtrate. Although the protease activity in the cotton-culture was about one third of that in the soy bean-culture, protein extraction by the former was higher in rate than that by the latter. It does not seem, theregore, that protease alone plays a role in extracting protein from the defatted soy bean. Several kinds of reducing sugar were produced in the incubation filtrate of pre-extracted soy bean after treatment with culture filtrates. Examination by paper chromatography revealed that arabinose and galactose occupied major part of the sugars which consisted of glucose, xylose, arabinose and galactose. These sugars appeared to occur in the incubation mixtures almost at the same rate as nitrogeneous compounds, but no detecable glucose and cellobiose, which are possible products from cellulose by the action of cellulase, were found in the mixtures. On the basis of these facts, it seemed reasonable to assume that hemicellulase and protease may mainly be responsible for the additional extraction of protein from defatted soy bean. However, the possibility cannot be excluded that a cellulase of the C_1-type might also participate in this process. Further studies are also necessary for the elucidation of the role of other enzymes, such as pectinase and protopectinase.
公益社団法人日本生物工学会の論文
1964-07-15

脱脂大豆からの蛋白質抽出率に対するIrpex lacteus培養濾液の影響

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