AN INEXPENSIVE CHEMOSTAT APPARATUS FOR THE STUDY OF MICROBIAL BIOFILMS

Continuous culture is a powerful technique for studying microbial biof ilms because it allows for the control of growth rate through nutrient limitation. These conditions offer a realistic view of how microorgan isms interact in natural ecosystems. The vast majority of biofilm rese arch is performed with batch cultures, due to the high cost of commerc ially produced chemostats. We describe a chemostat that could be assem bled on a limited budget and could be used in a variety of continuous culture experiments, including biofilm assays. Our design consists of an Erlenmeyer flask with custom-blown ports for aeration and waste rem oval/direct sampling, and a third port that allows microorganisms in t he reaction flask to be circulated through a modified Robbins device a nd returned via the mouth of the flask. This device enables the format ion of highly reproducible biofilm populations, of for example, Aeromo nas hydrophila, at various growth rates. As such, it is well-suited fo r the study of the physiology and genetics of biofilm bacteria. (C) 19 97 Elsevier Science B.V.