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Determination of Microbial Extracellular Enzyme Activity in Waters, Soils, and Sediments using High Throughput Microplate Assays
Published on: October 1, 2013
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A between-river comparison of extracellular-enzyme activity
1Department of Applied Biology, University of Hull, HU6 7RX, Hull, England.
Microbial Ecology
|November 5, 2013
Summary
River enzyme activity, including leucine aminopeptidase and phosphatase, showed similar patterns in the Ouse and Derwent rivers, likely driven by microbial communities rather than water chemistry. Free enzyme activity was also notable.
Area of Science:
- Environmental Microbiology
- Aquatic Chemistry
- Enzymology
Background:
- River ecosystems exhibit complex biochemical processes influenced by microbial communities and environmental factors.
- Extracellular enzyme activity is a key indicator of nutrient cycling and microbial function in aquatic environments.
- Understanding enzyme dynamics in rivers is crucial for assessing water quality and ecosystem health.
Purpose of the Study:
- To compare extracellular enzyme activity in two lowland rivers (Ouse and Derwent) in northeast England.
- To investigate the relationship between enzyme activity, planktonic microbiota, and physico-chemical conditions.
- To determine the proportion and significance of free enzyme activity in river water.
Main Methods:
- Assayed five extracellular enzymes: leucine aminopeptidase, phosphatase, β-D-glucosidase, β-D-galactosi-idase, and β-D-xylosidase over 15 months.
- Analyzed enzyme activity, planktonic microbiota, and physico-chemical parameters in river water samples.
- Quantified the proportion of free enzyme activity (<0.2 μm) for key enzymes.
Main Results:
- Mean enzyme activities followed a consistent order in both rivers: leucine aminopeptidase > phosphatase > β-D-glucosidase > β-D-galactosi-idase and β-D-xylosidase.
- No significant differences in enzyme activity were found between the rivers, but significant correlations existed for certain enzymes.
- Planktonic microbiota similarity, rather than physico-chemical conditions, was likely responsible for common enzyme regimes.
- A substantial and variable proportion of free enzyme activity was observed, suggesting a loose coupling with microbial variables.
- Potential for glucose uptake correlated with β-D-glucosidase activity, but leucine uptake was less than leucine-aminopeptidase activity.
Conclusions:
- River enzyme regimes are strongly influenced by microbial community composition.
- Free extracellular enzymes play a significant role in riverine biochemical processes.
- The studied enzyme activities provide insights into nutrient cycling and microbial dynamics in lowland rivers.
