CELL-SURFACE CHARGE AND INITIAL ATTACHMENT CHARACTERISTICS OF ROUGH STRAINS OF LISTERIA-MONOCYTOGENES

The relative negative surface charge and hydrophobicity of four bacter ial strains were evaluated by gravity flow and spin column methods. Th ere was no significant difference between the two methods, indicating that spin column chromatography is an acceptable alternative method of determining cell surface charge or hydrophobicity. Six strains of Lis teria monocytogenes which exhibited rough colony appearance were evalu ated for surface charge and hydrophobicity and their ability to contam inate beef muscle tissue. With one exception, all of the rough strains exhibited greater net negative surface charge and reduced ability to contaminate beef during the initial stages of attachment. Since greate r net negative cell surface charge has been positively correlated to a ttachment to beef tissue surfaces, the reduction in attachment exhibit ed by the rough strains was interpreted as an indication that attachme nt to beef tissue cannot be solely explained by cell surface charge.