Growth kinetics of a native toxigenic isolate of Yersinia enterocolitica CFR 2301 under the influence of incubation temperature, pH, sodium chloride and sodium nitrite

Growth attributes such as lag phase duration (LPD)
and growth rate (GR) estimates of a native toxigenic isolate of
Yersinia enterocolitica CFR 2301 were studied in a broth medium
under the influence of incubation temperature, pH, sodium
chloride and sodium nitrite. The experimental growth
curves derived from the central composite design based on 5
levels of factors namely incubation temperature (12–40 °C), pH
level (5.5–8.5), sodium chloride (0.5–5.5 %) and sodium nitrite
(0–200 ppm) were fitted using Baranyi and Gompertz functions,
individually. With both these functions, the observed
LPD values were similar ranging from 2.0 to 20.0 h and with
GR values ranging from 0.1 to 0.5/h. The predicted values of
LPD and GR estimates related well with observed values. The
experimental culture broths with GR estimates of 0.4 and 0.5/h
revealed positive phospholipase activity that is associated with
the toxigenic trait of phospholipase A in the culture of
Y. enterocolitica CFR 2301. The generated response surface
plots for LPDs and GR estimates show a definite behavioral
pattern under the influence of a combination of selected factors
and variables. Higher LPDs and lower GR estimates as the
indices of microbial safety could be of significance in developing
effective food safety protocols in the food chain.