Biochemistry of water-logged soils: Part II. The presence of a deaminase in water-logged soils and its rôle in the production of ammonia

Abstract

(1) The ammonia formed in water-logged soils was present mostly in the soil sediment. The surface water contained only a very small portion of the total amount produced. (2) Added ammonia was in a similar manner retained mostly in the soil itself. It could not be leached out by extraction with water nor volatilised with increase of temperature. There is evidence to show that the ammonia exists in the soil as an exchangeable base. (3) On allowing the soils to dry out the ammonia disappeared rapidly and corresponding amounts of nitrates were formed. Very little ammonia was lost by volatilisation. (4) The production of ammonia took place even in presence of volatile antiseptics. The reaction was shown to be brought about by a deaminase. (5) Studies with a number of proteins and ammo acids showed that only very simple amino compounds (glycine aspartic acid and asparagine) were deaminised. Witte's peptone, which contains amino acids, was also attacked. (6) An active preparation of enzyme was extracted from the soil with an aqueous solution of glycerin saturated with toluene. (7) Significant deaminising action was shown by the enzymes from cultures of the mixed microflora of the soils. (8) By acting on amino bodies that are otherwise resistant to biological action the deaminase probably helps to release readily available plant food. Its action should be of great importance in tropical swamp soils.