Staling in bacterial cultures.

When a strain of bacteria is streaked on a nutrient agar or gelatin medium containing a large number of its own viable cells, no growth appears even after long incubation. Eijkman (1904) and Powers and Levine (1937) suggested that this phenomenon of "staling" was due to specific, autoinhibitory substances and that it might serve as a basis for selective and differential techniques in determinative bacteriology. Frankel and Wynne (1951) studied the inhibitory effect of staled media as an antagonistic reaction among different species of bacteria and interpreted the staling as an effect of direct or contact antagonism. The data reported here emphasize that this type of staling is a manifestation of the stationary growth phase and seems not to be caused by specific inhibitory substances or proximity of cells but rather probably by the exhaustion of some factor or factors essential to the anabolic processes of the cell. Previous studies on broth cultures (e.g., Barnes, 1931; Jordan and Jacobs, 1944) have drawn similar conclusions as to the nature of the factors limiting the total extent of growth in bacterial cultures.