Effecfs of allophane on the enzymatic activity of a protease

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Abstract
Volcanic ash solis in Japan are remarkably high in humus content irrespective of climate or drainage. They are sometimes as high as 20 per cent or more in organic carbon content. This fact has led to a presumption that allophane would be retentive of organic matter (3, 8–11, 21). However, there is a few experimental evidence suggesting that allophane provides a great protection for organic matter against microbial activity. Aomine and Kodama (3) presented data that the rate of breakdown of cellulose or albumin by soil microorganisms was noticeably lower in an allophanic clay of Ando soil than an illitic or montmorillonitic clay of alluvial soils. Harada (8) showed a slow decomposition of albumin in an Ando paddy soil and its low effectiveness for rice crop as compared with ammorrium sulfate in the same soil. Jackman (9) suggested two possibilities for the stabilization of organic matter by allophane: an unusualIy strong adsorption of organic matter which is thereby protected from microbial attack, and a limitation of effective microbial activity because of a nutrient deficiency, a mineral toxicity, or a reduced enzyme activity due to adsorption of the enzymes by allophane. Considerable research works have been done in recent years on the effects of clay minerals on the microbial decomposition of organic matter (1, 7, 8, 12, 18, 20) and the enzamatic hydrolysis of pure organic compounds (6, 12-15, 17, 19). The minerals involved in the work are mostly montmorillonite and kaolinite. The present preliminary report shows that allophane strikingly inhibits the activity of a protease. The scope of this study is extending to cover several kinds of enzymes and their substrates and its results will be published in due course.