Extracellular Enzymes in Aquatic Biofilms: Microbial Interactions Vs Water Quality Effects in the Use of Organic Matter
Anna M. Romaní, Joan Artigas and Irene Ylla
from: Microbial Biofilms: Current Research and Applications (Edited by: Gavin Lear and Gillian D. Lewis). Caister Academic Press, U.K. (2012)
Biofilms in aquatic ecosystems colonize various compartments (sand, rocks, leaves) and play a key role in the uptake of inorganic and organic nutrients. Due to their extracellular enzyme capabilities, biofilm microorganisms are able to use organic matter from the surrounding water and increasing activities are related to the availability of biodegradable organic carbon. The most common extracellular enzymes analysed are those involved in the decomposition of polysaccharides, peptides and organic phosphorus compounds, and changes in enzyme expression have been related to the use of different sources of organic matter available in the ecosystem (i.e., during drought-storm and/or pollution episodes). Enzymes important for microbial acquisition of nitrogen and phosphorus also respond to nutrient content and/or imbalances in the flowing water. Additionally, biofilm extracellular enzyme activities are modified by the internal recycling of organic matter and microbial interactions (competition/synergism) within the biofilm, such as algal-bacterial and fungal-bacterial interactions. Although an extensive knowledge of the biofilm structure is required for the interpretation of extracellular enzyme activities in aquatic biofilms, they give a very useful, integrative measure of the biofilm community function in relation to organic matter use and cycling read more ...