Methods to extract the exopolymeric matrix from biofilms: A comparative study

To study the composition of a biofilm a previous extraction method is requi red to separate cells from the matrix. There are several methods reported i n the literature; however they are not efficient or promote leakage of intr acellular material. In this work several extraction methods were assayed in mixed culture and pure culture biofilms and their efficiency was evaluated by the amount of organic carbon, proteins and intracellular material extra cted. The results showed that the extraction with glutaraldehyde 3% (wiv) w as the most suitable method, extracting great amounts of organic carbon wit hout promoting cell lysis or permeabilization. Glutaraldehyde is a bifuncti onal reagent that binds to cell walls avoiding their permeabilization and t he biofilm matrix is solubilized in the solution. (C) 1999 IAWQ Published b y Elsevier Science Ltd. All rights reserved.