J D Parry1, A K Holmes, M E Unwin, J Laybourn-Parry. 1. Department of Biological Sciences, The Lancaster Environment Centre, Faculty of Science and Technology, Lancaster University, Lancaster LA1 4YQ, UK. j.parry@lancaster.ac.uk
Abstract
AIMS: This study evaluated the effect of protozoan movement and grazing on the topography of a dual-bacterial biofilm using both conventional light microscopy and a new ultrasonic technique. METHODS AND RESULTS: Coupons of dialysis membrane were incubated in Chalkley's medium for 3 days at 23 degrees C in the presence of bacteria (Pseudomonas aeruginosa and Klebsiella aerogenes) alone, or in co-culture with the flagellate Bodo designis, the ciliate Tetrahymena pyriformis or the amoeba Acanthamoeba castellanii. Amoebic presence resulted in a confluent biofilm similar to the bacteria-only biofilm while the flagellate and ciliate created more diverse biofilm topographies comprising bacterial microcolonies and cavities. CONCLUSIONS: The four distinct biofilm topographies were successfully discerned with ultrasonic imaging and the method yielded information similar to that obtained with conventional light microscopy. SIGNIFICANCE AND IMPACT OF THE STUDY: Ultrasonic imaging provides a potential way forward in the development of a portable, nondestructive technique for profiling the topography of biofilms in situ, which might aid in the future management of biofouling.
AIMS: This study evaluated the effect of protozoan movement and grazing on the topography of a dual-bacterial biofilm using both conventional light microscopy and a new ultrasonic technique. METHODS AND RESULTS: Coupons of dialysis membrane were incubated in Chalkley's medium for 3 days at 23 degrees C in the presence of bacteria (Pseudomonas aeruginosa and Klebsiella aerogenes) alone, or in co-culture with the flagellate Bodo designis, the ciliate Tetrahymena pyriformis or the amoeba Acanthamoeba castellanii. Amoebic presence resulted in a confluent biofilm similar to the bacteria-only biofilm while the flagellate and ciliate created more diverse biofilm topographies comprising bacterial microcolonies and cavities. CONCLUSIONS: The four distinct biofilm topographies were successfully discerned with ultrasonic imaging and the method yielded information similar to that obtained with conventional light microscopy. SIGNIFICANCE AND IMPACT OF THE STUDY: Ultrasonic imaging provides a potential way forward in the development of a portable, nondestructive technique for profiling the topography of biofilms in situ, which might aid in the future management of biofouling.