P. Hammer et Hg. Walte, PATHOGENICITY TESTING OF HEAT-RESISTANT M ESOPHILIC SPOREFORMERS FROMUHT-MILK, Kieler Milchwirtschaftliche Forschungsberichte, 48(2), 1996, pp. 151-161
Highly heat resistant mesophilic sporeformers (HRS) were first detecte
d in UHT-milk in 1985 when new regulations (EC-Directive 85/397) conce
rning the bacterial cell count came into effect. By genetical and bioc
hemical characterization a new Bacillus species was established. To pr
event a possible health hazard for the consumer the HRS has to be test
ed for pathogenicity. For this reason 15 HRS strains were tested in a
cell-culture modell and in embryonized chicken eggs. The cell culture
was evaluated for cytotoxicity by morphological examination of the cel
l and an enzyme-release test with no cytotoxic effects observed. The c
hicken embryos were examined for pathological signs, teratogenic effec
ts, growth retardation and the relative embryo weight. These parameter
s were statistically evaluated by analysing variances by a linear cont
rast method and additional Tukey-, Scheffe- and I-test. No significant
differences between eggs inoculated with HRS strains and noninoculate
d strains were observed. In combining the results of cytotoxicity test
s and chicken embryo assays the HRS can be estimated most likely as ap
athogenic.