SEDIMENT PHOSPHATASES OF THE BREITENBACH, A FIRST-ORDER CENTRAL-EUROPEAN STREAM

Sediment phosphatases of a small first-order stream were investigated using 4-methylumbelliferyl phosphate. The degradation of organically b ound phosphorus was inferred to involve an unidentified number of isoz ymes. Two pH-dependent isozyme groups could be identified, with activi ty optima occurring under acid (pH 5.0-6.0) and alkaline (pH 8.0-9.0) conditions. The multiphasic kinetic responses of the phosphatases vari ed markedly from sample to sample and were not correlated with the mea sured sediment substrate pools (organic matter, total phosphorus, solu ble reactive phosphorus). The presence of multiple phosphatases implie s that regulation of enzyme synthesis occurs in response to the compet ition for specific substrates.