Influence of deletion of HWP1 , BCR1 and ALS3 and on establishment of early firm adhesion. Biofilms formed from the strains indicated at the top of each column were harvested at 40 min and the tubing was drained. The top row are pictures of the underside of the tubing. Visible biofilm remained after draining the tubing for the reference strain (DAY286) and the hwp1/hwp1 mutant, while no visible biofilm remained for the bcr1/bcr1 mutant. There was some residual biofilm left after draining the tubing colonized by the als3/als3 mutant (before the ethanol rinse steps), but the adhesion to the surface was clearly much less than the reference strain. SEM images of the tubing in the second row indicated that multilayer biofilm remained on the surface of the tubing for the reference strain and the hpw1/hpw1 mutant, while very few cells could be found for the bcr1/bcr1 and als3/als3 mutants. The most heavily colonized regions that were found are shown. (The ethanol dehydration removed all visible biofilm from the tubing for bcr1/bcr1 and als3/als3 mutant strains).