Microbial survival curves - The reality of flat shoulders and absolute thermal death times

摘要: Abstract Occasionally, experimental survival curves of micro-organisms exposed to a lethal agent have flat region and traditionally it has been interpreted as evidence the existence “shoulder”. However, if curve is considered cumulative distribution events, which reflects spectrum resistances, or sensitivities, then when distribution's mean, mode, large relative its spread, resembling “shoulder” will be observed irrespective whether symmetric skewed. Computer simulated generated with Fermi Weibull distributions models demonstrate that shape alone is, therefore, insufficient confirm any specific inactivation mechanisms at cellular molecular level, although can refute some. Microbial mortality also assumed process following an exponential decay hence certain degree inevitable. It not inconceivable, however, there absolute thermal death time survivors are being progressively weakened by prolonged exposure agent. This testable possibility demonstrated two mathematical models.