AME 83:161-166 (2019)  -  DOI: https://doi.org/10.3354/ame01914

ABSTRACT: Extracellular enzymatic activities (EEAs) of microbial biofilms are a key component of organic matter transformation in streams, but their measurement, in particular on leaves, is often associated with high variability. We investigated the potential of standardized substrata (cotton strips and wooden [poplar] sticks) to reduce measurement heterogeneity of 3 microbial EEAs (β-D-glucosidase [GLU], N-acetyl-glucosaminidase [NAG] and phosphatase [PHO]) in comparison with leaves. Substrata were placed in a temperate forest stream for 8 wk. Global enzymatic activities were within the same order of magnitude among substrata. Variability among replicates was dependent on the time phase of the experiment: in the short term (≤2 wk), leaves, wood and cotton exhibited the lowest variation among replicates for PHO, GLU and NAG activity measurements, respectively, but over a longer period (>2 wk), cotton was the most suitable substrata to precisely evaluate the 3 activities. Cotton is thus of great interest for monitoring extracellular enzymatic activities in lotic environments.

KEY WORDS: Stream · Cotton · Wood · β-glucosidase · N-acetylglucosaminidase · Phosphatase