روزنامه با شماره پیاپی سال 2002

6

17

22

The power–time curves of growth of three strains of petroleum bacteria at different NaCl concentrations at 40.0 and 50.0 °C have been determined by using a 2277 Thermometric Thermal Activity Analyser. An equation of a power–time curve, ln[αPK/P(t)−1]=ln[(αK−N0)/N0]−αkt, was established based on the generalized logistic equation, where P(t) is the thermal power at time t, K the carrying capacity, PK=P0K, P0 the thermal power of one cell, N0 the bacterial population at time zero, α=(k−D)/k. The method of four observed points with the same time interval was used to calculate the value of PK. The growth rate constant k and the death rate constant D were calculated. The NaCl concentration of optimum growth rate of petroleum bacteria at 40.0 and 50.0 °C, respectively, have been obtained according to the curves k−D versus NaCl concentration, which are 0.26, 0.54 and 0.57 mol l−1 for B-1, B-2 and B-3, respectively, at 50.0 °C, 0.26, 0.55 and 0.56 mol l−1 for B-1, B-2 and B-3, respectively, at 40.0 °C. The results indicated that the effect of temperature on NaCl concentration of optimum growth rate was small.

Food Microbiology

2002

Food Microbiology