Abstract
The fluorogenic substrate Enzyme-Labeled Fluorescence 97 (ELF-P) is hydrolyzed by the P-cleaving enzyme phosphatase, producing ELF 97 alcohol (ELFA), a fluorescent-insoluble product. This reaction is used for monitoring phosphatase activity at the single-cell level. Most frequently, ELF-P has been used to determine the P-limitation status of microphytoplankton, but rarely of heterotrophic bacteria. We incubated ELF-P on filters to monitor marine bacterial cultures and oligotrophic Mediterranean Sea samples. Results were compared to classical measurements of bulk alkaline phosphatase activity using the fluorogenic substrate 4-methylumbelliferyl phosphate (MUF-P). A high percentage of the cultured cells were labeled with ELFA (the ratio of ELFA spots to total DAPI counts in P-limited cultures ranged from 26 to 100%, depending on the strain). In contrast, this ratio never exceeded 0.01 % in Mediterranean samples, even when P was demonstrated to be a significant limiting factor. This protocol is useful for application on cruises and with cultures, but was not sufficiently sensitive to detect P-stressed bacterial cells in oligotrophic marine environments.
Original language | English (US) |
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Pages (from-to) | 245-251 |
Number of pages | 7 |
Journal | Aquatic Microbial Ecology |
Volume | 52 |
Issue number | 3 |
DOIs | |
State | Published - Sep 2008 |
Externally published | Yes |
Keywords
- Alkaline phosphatase
- Cell specific activity
- ELF97 phosphatase substrate
- Ectoenzyme
- Marine bacteria
- Phosphorus limitation
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Aquatic Science