Listeria is especially scary because it can reproduce at a pH as low as 4.1 (Jay et al., 2005)
Unfortunately, it also can grow at refrigerator temps and below, as low as 29.3°F, albeit very slowly. (Hudson et al., 1994; Grau and Vanderline, 1990; Khan et.al.,
That's why it's important to be very careful when storing certain foods at refrigerator temperatures for an extended period of time.
Hudson, J.A., Mott, S.J., and Penney, N. 1994. Growth of Listeria monocytogenes, Aeromonas hydrophila, Yersinia enterocolitica on
vacuum and saturated carbon dioxide controlled atmosphere-packaged sliced roast beef. J. Food Protect. 57 (3): 204-208.
Jay, J.M., Loessner, M.J., and Golden, D.A. 2005. Modern Food Microbiology 7th edition. Springer Science + Business Media. New
Grau, F.H., and Vanderline, P.B. 1990. Growth of Listeria monocytogenes on vacuum packaged beef. J. Food Protect. 53(9): 452-459.
Khan, M.A., Palmas, C.V., Seaman, A., and Woodbine, M. 1972. Survival versus growth of a facultative psychrotroph. Acta Microbiol.
Acad. Sci. Hung. 19: 357-362., as cited by Rosenow, E.M. and Marth, E.H. 1987. Listeria, listeriosis and dairy foods: a review.
Cultured Dairy Products J. 22(4):13-17.