Aminopeptidase and phosphatase activities in basins of Lake Hiidenvesi dominated by cyanobacteria and in laboratory grown Anabaena

Abstract

1. Extracellular enzyme activities were examined in freshwater basins representing a transition from hypertrophy to mesotrophy and in axenic cyanobacterial cultures to evaluate the ecological role of extracellular enzyme activities of cyanobacteria. 2. Aminopeptidase activity was related to the trophic status of the lake basins. The activity was highest in the most eutrophic basin and decreased in the less nutrient‐rich basins. Cyanobacteria were the most important autotrophic organisms and aminopeptidase activity was positively associated with cyanobacterial biomass. 3. In an axenic Anabaena batch culture, nitrogenase activity was several orders of magnitude higher than leucine aminopeptidase activity. Nitrate did not have an effect on aminopeptidase activity or growth, but significantly reduced the rate of nitrogen fixation. A high phosphorus concentration at the beginning of the Anabaena batch‐culture experiment resulted in reduced phosphatase activity. 4. In Lake Hiidenvesi, aminopeptidase activity probably originated mostly from attached bacteria and less so from cyanobacteria.

Limitations of using extracellular alkaline phosphatase activities as a general indicator for describing P deficiency of phytoplankton in Chinese shallow lakes

“…7 Algal composition in terms of abundance in all studied lakes (lakes abbreviation: L Liangzi, N Niushan, H Houguan, B Baoan, Lu Luhu, Y Yuehu) (Vaitomaa et al 2002). Shortly, APA contributed by bacteria complex the relationship between APA and ambient phosphorus, thereby weakening the validity of its use as an indicator of phytoplankton P limitation.…”

Extracellular enzyme activities in benthic cyanobacterial mats: comparison between nutrient- enriched and control sites in marshes ofnorthern Belize

“…While techniques were developed to measure extracellular enzyme activities (Hoppe 1983), the problem of determining which organisms are producing the activity remains (Vaitomaa et al 2002). Few studies have tried to determine the ecological role of cyanobacterial enzymes (Vaitomaa et al 2002(Vaitomaa et al , 2troj-sová et al 2003.…”

“…Few studies have tried to determine the ecological role of cyanobacterial enzymes (Vaitomaa et al 2002(Vaitomaa et al , 2troj-sová et al 2003. One of the reasons for this may be that cyanobacterial surfaces are often colonized by bacteria (Paerl 1982) and it is difficult to distinguish between the 2 enzyme sources.…”

“…Extracellular enzymes are produced by a variety of organisms, but the majority of their activity seems to be derived from microbial processes (2trojsová et al 2003). These processes are crucial in the remineralization of nutrients and primary production; therefore, studying extracellular enzyme activities and distribution may provide important information about the cycling of nutrients in ecosystems.While techniques were developed to measure extracellular enzyme activities (Hoppe 1983), the problem of determining which organisms are producing the activity remains (Vaitomaa et al 2002). Few studies have tried to determine the ecological role of cyanobacterial enzymes (Vaitomaa et al 2002(Vaitomaa et al , 2troj-sová et al 2003.…”

The alteration of Microcystis aeruginosa biomass and dissolved microcystin‐LR concentration following exposure to plant‐producing phenols

“…The production and excretion of alkaline phosphatase plays a key role especially in a water reservoir with a low contamination of inorganic phosphate. In lakes, APA is associated with the blooms of several species (Vaitomaa et al, 2002;Strojsova et al, 2003;Glibert et al, 2004). The growth of M. aeruginosa is often P-limited (Ou et al, 2005) and the inhibition of APA makes the organic phosphorus unavailable for them.…”