Enzymatic Hydrolysis of Organic Phosphorus

Several abiotic processes can regulate the bioavailability of organic phosphorus in soils and sediments. These processes include  

Microbial biomass regulates storage and transformation of phosphorus, and flow of phosphorus through the soil microbial pool can be substantial. In phosphorus-limited wetlands containing significant quantities of organic phosphorus, bioavailability of phosphorus may be regulated by 

FIGURE 9.48 A schematic showing enzyme-mediated chemical reactions involved in breakdown of organic phosphorus. S = substrate E = enzyme. (Newman, S., South Florida Water Management District, West Palm Beach, Florida.) 

Enzymes play a key role in regulating phosphorus release from organic phosphorus, especially in P-limited wetland systems. Some of the enzymes involved are  

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Quiquampoix, H., and Mousain, D. (2005) Enzymatic Hydrolysis of Organic Phosphorus, CAB International, Wallingford. 

Shan et al. (1994) used alkaline phosphatase from Escherichia coli in immobilized enzyme reactors in a flow injection analysis system to perform rapid on-line enzymatic hydrolysis of organic phosphorus and detection of the released phosphate as molybdate-reactive phosphorus. This approach has several advantages compared with the conventional batch reaction approach ... 

Mortland, M.M. and Gieseking, J.E. (1952) The influence of clay minerals on the enzymatic hydrolysis of organic phosphorus compounds. Soil Science Society of America Proceedings 15, 10-13. 

Enzymatic hydrolysis of organic phosphorus is an essential step in the biogeo-chemical phosphorus cycle, including the phosphorus nutrition of plants and microorganisms (see Oberson and Joner, Chapter 7 Richardson et al., Chapter 8 Heath, Chapter 9, this volume) and the transfer of organic phosphorus from soils to water bodies (see Turner, Chapter 12, this volume). It also plays a role in gene fluxes in the environment by its effect on the residual extracellular DNA in soil, and in the degradation of... 

A further limitation of the CENTURY phosphorus model is the lack of an explicit representation of the impact of soil enzymes on the mineralization of organic phosphorus compounds. The results presented in this book indicate that there is limited data with which to quantify the relative importance of enzymatic hydrolysis of organic phosphorus [biochemical mineralization) vs. organic phosphorus mineralization associated with the decomposition of organic compounds [biological mineralization). It is very difficult to develop models that include enzymatic mineralization of organic phosphorus without data to quantify the relative importance of this process. 

Mortland and Gieseking (1952) found that all the clays that they studied exerted an inhibiting effect upon the enzymatic hydrolysis of organic phosphorus c ompounds. The effect of the clays was as follows montmorillonite > Cisne > illite > kaolinite. The inhibition of phosphatase activity corresponded closely to the base exchange capacity of the clays, and was due primarily to their effect on the enzyme and riot to adsorption of the organic phosphorus compounds by the clays. 

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