Original paper
Organic matter degradation and nutrient regeneration in Australian freshwaters: I. Methods for exoenzyme assays in turbid aquatic environments
Boon, Paul I.
Archiv für Hydrobiologie Volume 115 Number 3 (1989), p. 339 - 359
44 references
published: May 19, 1989
DOI: 10.1127/archiv-hydrobiol/115/1989/339
ArtNo. ESP141011503001, Price: 29.00 €
Abstract
A method was developed using p-nitrophenol and p-nitroaniline derivatives to measure exoenzyme activity in turbid waters. Maximum activity occurred at temperatures of 40°C or above. The response to variations in pH was complex, with some systems showing no clear optimum but others showing an optimum at either pH of 7.5 or pH 9.0—10. Only 25 % of the enzyme system-site combinations generated linear Lineweaver -Burke plots, indicating that many exoenzyme systems were active simultaneously in the degradation of organic detritus. The maximum rate of activity occurred with aminopeptidase (up to 107 µmoll-1 d-1), followed by alkaline phosphatase (up to 42 µmoll-1 d-1). There was little lipase or α-D glucosidase activity in the any water body, except in a highly-eutrophied lagoon. Rates were consistently higher in billabongs than in rivers, and most activity was associated with particles rather than being free in the water column.
Keywords
p-nitrophenol • p-nitroaniline • derivatives • Line-weaver Burke plots • aminopeptidase • lipase • α-D glucosidase activity