Biofilm formation by Vibrio harveyi on surfaces

The role of biofilm in the survival and persistence of the bacterial shrimp pathogen Vibrio harveyi and its possible role in perpetuating infection in shrimp hatcheries was studied. Vibrio harveyi formed biofilms on all three substrates tested: cement slab, high density polyethylene (HDPE) plastic and steel coupons. Cell density was highest on the plastic surface followed by the cement slab and the steel surface. Biofilm on the three surfaces also exhibited differential sensitivity to the sanitiser chlorine, maximum resistance being found on the concrete slab followed by plastic and steel coupons. Planktonic cells were sensitive to short exposure to low levels of chlorine. Biofilm formation occurred even in the presence of the antibiotics chloramphenicol and tetracycline, both added to the medium at 50 ppm.