BIOFILMS ASSOCIATED WITH POULTRY-PROCESSING EQUIPMENT

Aerobic and Gram-negative bacteria were enumerated on non-metallic sur faces and stainless steel test pieces attached to equipment surfaces b y swabbing and a mechanical dislodging procedure, respectively, in a S outh African grade B poultry processing plant. Changes in bacterial nu mbers were also monitored over time on metal test pieces. The highest bacterial counts were obtained from non-metallic surfaces such as rubb er fingered pluckers and plastic defeathering curtains which exceeded the highest counts found on the metal surfaces by at least 1 log CFU c m(-2). Gram-negative bacterial counts on all non-metallic surface type s were at least 2 log CFU cm(-2) lower than corresponding aerobic plat e counts. On metal surfaces, the highest microbial numbers were obtain ed after 14 days exposure, with aerobic plate counts ranging from 3.57 log CFU cm(-2) to 5.13 log CFU cm(-2), and Gram-negative counts from 0.70 log CFU cm(-2) to 3.31 log CFU cm(-2). Scanning electron microsco py confirmed the presence of bacterial cells on non-metallic and metal lic surfaces associated with poultry processing. Rubber 'fingers', pla stic curtains, conveyor belt material and stainless steel test surface s placed on the scald tank overflow and several chutes revealed extens ive and often confluent bacterial biofilms. Extracellular polymeric su bstances, but few bacterial cells were visible on test pieces placed o n evisceration equipment, spinchiller blades and the spinchiller outle t.