Regulation of b- and a-Glycolytic Activities in the Sediments of a Eutrophic Lake.

ABSTRACT

Temporal changes in a- and b-glucosidase activities, dissolved organic matter content, and bacterial biomass were studied in the superficial sediment layer of a eutrophic lake during the period of anoxia. The mean a- and b-glucosidase activities were 30.7 +/- 11.0 and 15.1 +/- 6.2 nmol h-1 g-1 of dry sediment, respectively. The specifc b-glucosidase activity seemed to be stimulated by carbohydrates (r = 0.80, P <0.05), whereas the specifc a-glucosidase activity was negatively correlated with the dissolved protein concentration (r = -0.72, P <0.10). To test the effect of organic matter on hydrolytic activities under controlled conditions, changes in specific activities were studied in relation to the concentrations of different types of organic matter phytoplankton, polymers (proteins, cellobiose, and starch) and monomers (glucose and amino acids). The specifc a- and b-glucosidase activities were strongly induced by their natural substrates (starch and cellobiose, respectively) (P <0.05) and were not inhibited by glucose. Proteins inhibited these activities (P <0.05), whereas supplementation with amino acids had no effect on specifc glycolytic activities.