Release of microbial contamination from fractured solids |
| |
| Authors: | N J Petersen R G Cornell J R Puleo |
| |
| Institution: | (1) Planetary Quarantine Unit, Phoenix Field Station Section, National Communicable Disease Center Public Health Service, Dept of Health Education and Welfare, Phoenix, Ariz., USA;(2) Dept. of Statistics, Florida State University, Tallahassee, Fla., USA;(3) Spacecraft Bioassay Laboratory, National Communicable Disease Center, USPHS, Cape Kennedy, Fla, USA |
| |
| Abstract: | Estimation of the probability of release of microbial contamination from the interior of solids upon fracture due to impact is essential to the formulation of planetary quarantine and spacecraft sterilization requirements. A model system was designed in which known concentrations of bacterial spores were incorporated in methyl methacrylate plastic. Pieces of plastic were fractured in a uniform manner exposing interior surface areas of consistent and measurable size. Known surface areas were incubated in sets of 20 culture tubes containing liquid growth medium. The subsequent occurrence of visible growth expressed as percent of tubes positive was interpreted as an estimate of the probability of release of at least one viable micro-organism.From these experiments probability of release as a function of microbial concentration in plastic was estimated for exposed interior surface areas of 30.6, 61.2, 91.8 or 122.4 mm2. Good agreement of the empirical results with a theoretical mathematical model of the probability of release of contamination from solids was demonstrated. Analysis of the data using the maximum likelihood procedure provided a means of calculating a proportionality constant representing the effective thickness of the exposed area and the characteristics of the recovery procedure. |
| |
| Keywords: | |
| 本文献已被 SpringerLink 等数据库收录！ |
|
