DISTRIBUTION OF PHOSPHOMONOESTERASES IN SOILS

Publisher Website
Google Scholar
Abstract
Several phosphatases are present in soils. The distribution of phosphomonoesterases [EC 3.1.3] (acid and alkaline phosphatases) were determined. The activities of these enzymes were associated with surface soils and they decrease with depth. Acid phosphatase [EC 3.1.3.2] was predominent in acid soils, and alkaline phosphatase [EC 3.1.3.1] was predominant in alkaline soils. The activities of these enzymes were significantly correlated with organic C. The log of acid phosphatase activity was significantly but negatively correlated with the pH of 38 samples of 5 soil profiles examined. Regression analysis showed that acid phosphatase activity was significantly but negatively correlated, while alkaline phosphatase activity was significantly and positively correlated, with the pH of 11 surface soil studies. [Phosphodiesterases EC 3.1.4 were also analyzed.] Orthophosphate inhibited phosphomonoesterases in soils. At 10 .mu.mol PO43-/g of soil, inhibition of acid phosphatase activity ranged 21-42%, and the inhibition of alkaline phosphatase activity ranged 17-51%, in 6 surface soils. The inhibition of these enzymes by orthophosphate decreased when the amount of orthophosphate added decreased from 10 .mu.mol to 1 .mu.mol/g of soils. The inhibition by orthophosphate showed competitive kinetics. The results explain the variation of Km values of p-nitrophenyl phosphate for acid and alkaline phosphatases and the observed decrease in phosphatase activity with organic P mineralization in soils. [Phosphomonoesterases in soil are derived from plants, microorganisms and decomposing litter.].

This publication has 3 references indexed in Scilit: