Observations on listerias at dysgenesic concentrations of NaCl

Interesting morphological and Gram-stain changes of listerias in relationship to the concentration of NaCl were observed. When incubated at 23 degrees C at a concentration of 6% (w/v) the listerias tended to form chains, and in concentrations of 10-11% NaCl they presented aberrant forms as long filaments, some of them forming circles, and they lose affinity for Gram stain. Similar changes were observed, but at different concentrations of NaCl, when incubation was at 37 degrees C.