AME prepress abstract  -  DOI:

Assessing extracellular enzymatic activities of biofilms on natural and standardized organic substrata immersed in a stream

Muriel Joly*, Clarisse Mallet, Joan Artigas


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, poplar sticks) to reduce measurement heterogeneity of three microbial EEAs (β-D-glucosidase (GLU), N-acetyl-glucosaminidase (NAG) and phosphatase (PHO)) in comparison with leaves. Substrata were placed in a temperate forested stream for 8 weeks. Global enzymatic activities were within the same order of magnitude among substrata. Variability among replicates were dependent on the time phase of the experiment: at short term (≤ 2 weeks), leaves, wood and cotton exhibited the lowest variation among replicates for PHO, GLU and NAG activity measurements respectively but at longer term (> 2 weeks), cotton was the most suitable substrata to evaluate precisely the three activities. Cotton is then of great interest to monitor extracellular enzymatic activities in lotic environments.