Tp. Robinson et al., THE EFFECT OF THE GROWTH ENVIRONMENT ON THE LAG PHASE OF LISTERIA-MONOCYTOGENES, International journal of food microbiology, 44(1-2), 1998, pp. 83-92
The duration of lag in Listeria monocytogenes was examined in relation
to the physico-chemical properties of the growth environment. It was
supposed that lag would be determined by two hypothetical quantities,
the amount of work that a cell has to perform to adapt to new conditio
ns and the rate at which it can perform that work. If the rate at whic
h the cell can perform the necessary work is a function of the maximum
specific growth rate in the new environment, the hypothesis predicts
that lag time should be related in some way to growth rate, provided c
ells are initially in approximately the same physiological state. Lite
rature data suggest this is true for many organisms when temperature i
s the sole growth limiting factor. However, lag times of L. monocytoge
nes displayed an unusual response to temperature in which lag times of
cells precultured at 37 degrees C were shorter at 15 degrees C than a
t 20 degrees C or 25 degrees C. Analysis of data from the Food Micromo
del in which growth of L. monocytogenes was controlled by combinations
of pH, NaCl concentration and temperature, showed that there was a li
near relationship between lag time and mean generation time although t
here was much scatter in the data. When the effects of pH, solute type
and concentration were investigated individually in this work the cor
relation between lag time and mean generation time was often poor. It
would thus appear that the relationship between growth environment and
lag time is more complex than the corresponding relationship between
growth environment and maximum specific growth rate. (C) 1998 Elsevier
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