The attachment efficiency of cell-walled and L-forms of Listeria monocytogenes to stainless steel

There is limited knowledge regarding the attachment of cell wall-deficient forms of Listeria monocytogenes to abiotic and food contact surfaces. A typical L-form phenotype of Listeria monocytogenes was induced, propagated and recovered in both broth and plate culture by exposure to sub-lethal concentrations of ampicillin. Attachment of both cell-walled and L-forms to stainless steel were compared using viable counts. L-forms possessed no cell wall material and were present as spherical cells or small rods. L-form cells had the capacity to attach sufficiently well to stainless steel (0.3% of cells attached) with a higher efficiency than parental cells (0.002%) after 8 h exposure to culture. After longer exposure times of 18 h, the parental cells attached with slightly higher efficiency (0.8%) than L-forms cells (0.625%). The ability of Listeria monocytogenes L-forms to attach to stainless steel may suggest that a classical rigid cell wall structure is not a prerequisite for cell adhesion in vitro.