Dry-heat destruction of lipopolysaccharide: dry-heat destruction kinetics

Abstract

Dry-heat destruction kinetics of lipopolysaccharides from Escherichia coli, Serratia marcescens, and Salmonella typhosa at 170 to 250 degrees C are described. The destruction rate seems to follow the second order and can be linearized by the equation, log y = a + b . -10cx. Because c is the slope, 1/c = D3. Both a and b are constant at a given temperature and are linear functions of temperature. The D(3)170, D(3)190, D(3)210, D(3)230, and D(3)250 values for E. coli lipopolysaccharide are 251, 99.4, 33.3, 12.3, and 4.99 min, respectively, with a z value of 46.4 min. The D values for lipopolysaccharides from S. marcescens and S. typhosa are not significantly different from those from E. coli lipopolysaccharide.

Endotoxin inactivation via steam‐heat treatment in dilute simethicone emulsions used in biopharmaceutical processes

“…The standard deviations of the slope and intercept were 0.002 C 21 and 0.203, respectively. The resulting Z value was calculated to be 20.9 6 0.7 C, which is consistent with other values reported in the literature 16,18,19 (Table 3). In the slow regime, the calculated rate constants departed from the expected Arrheniusbased temperature dependence observed in the fast regime in the temperature range examined.…”

“…These comparisons enabled accurate detection and quantification of a test sample's endotoxin content. Previous investigators have demonstrated that results obtained from the LAL assay results were consistent with pyrogen testing, 19,22 suggesting that this is a suitable method to quantify endotoxin inactivation from steam-heat treatment.…”

“…20 Later work by Ludwig and Avis 16,17 interpreted LPS inactivation to be biphasic, wherein endotoxin reduction was assessed using two temperature-dependent linear fits. Between 170 C and 250 C, calculated D values have been reported from 0.15 min to 3.4 h 16,[18][19][20] (Figure 2). Z values vary depending on testing conditions with reported values of 15 C, 19 30.9 C, 18 46.8 C, 16,19 and 53.7 C 19 being observed.…”

“…Between 170 C and 250 C, calculated D values have been reported from 0.15 min to 3.4 h 16,[18][19][20] (Figure 2). Z values vary depending on testing conditions with reported values of 15 C, 19 30.9 C, 18 46.8 C, 16,19 and 53.7 C 19 being observed. In addition, the time required to achieve 3-log reduction in endotoxin has ranged from 0.5 minutes to 2.5 h 16,18,19 between 150 C and 250 C. Tsuji and Harrison 19 noted that the kinetics describing the dry-heat destruction of LPS was similar for the different bacterial populations examined.…”

“…Conversely, dwell times spent predominantly in the slow regime resulted in a lower observed LRV. Factors including endotoxin concentration, 15,21-24 temperature, 15,24 the presence of nonionic surfactants 22,23 and/or divalent cations, 21 steam saturation ratio, 24 and/or other inherent structural polymorphisms between endotoxins 19 Li et al, 15 and Miyamoto et al 24 ) is plotted as a function of temperature (x-axis). D values calculated for the fast and slow regime are labeled for dry-heat treatment and hydrothermal processing.…”