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.

中文翻译：

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评估生物膜对浸入溪流中的天然和标准化有机基质的细胞外酶活性

摘要：微生物生物膜的细胞外酶促活性（EEA）是河流中有机物转化的关键组成部分，但对它们的测量（尤其是在叶片上）通常与高变异性相关。我们研究了标准化基质（棉条和木质[杨树]棍）减少3种微生物EEA（β-D-葡萄糖苷酶[GLU]，N-乙酰氨基葡萄糖苷酶[NAG]和磷酸酶[PHO]）的测量异质性的潜力。与叶子比较。将基质置于温带森林溪流中8周。各基质之间的整体酶活性在同一数量级内。复制品之间的差异取决于实验的时间阶段：在短期内（≤2 wk），对于PHO，GLU和NAG活性测量，树叶，木材和棉花在复制品中表现出最低的变化，分别是，但在较长的时期（> 2周）中，棉花是最适合精确评估这3种活动的基质。因此，棉花对于在抽水环境中监测细胞外酶活性非常感兴趣。