Y. Wu et al., A comparison of the Bioscreen method and microscopy for the determination of lag times of individual cells of Listeria monocytogenes, LETT APPL M, 30(6), 2000, pp. 468-472
Lag phase durations (t(Lag)) Of individual Listeria monocytogenes cells wer
e analysed using the NightOwl Molecular Imaging System, and results were co
mpared with mean individual cell lag times (t(L)) Obtained from the detecti
on time (t(d)) method using Bioscreen. With Bioscreen, an average t(L) of 6
. 39 +/- 0 . 89 h was obtained from five separate experiments. With the Ni
ghtOwl method, an average t(Lag) of 2 . 73 +/- 0 . 06 h was obtained from t
hree experiments consisting of eight total replicates. Lag values from the
NightOwl and Bioscreen are related by the equation: t(Lag) = t(L) + DT wher
e DT is the doubling time. The equivalent t(Lag) mean value for the Bioscre
en method was 7 . 11 +/- 0 . 84 h. Individual lag times measured by both me
thods were normally distributed (r(2) for Bioscreen and NightOwl ranged fro
m 0 . 951 to 0 . 999 and from 0 . 884 to 0 . 982, respectively). The result
s suggest that the NightOwl method can provide accurate estimates of indivi
dual cell lag times, which will facilitate the development of combined disc
rete continuous models for bacterial growth.