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Abstract
SUMMARY: A sensitive, small-scale assay for penicillin showed the production of penicillin in sterilized but otherwise unsupplemented soils inoculated with a wild-type Penicillium chrysogenum. The same Penicillium was capable of competitively invading maize seeds equilibrated at 95 % relative humidity, and producing penicillin in the seed. Problems with gross contamination of some batches of seeds were overcome by the use of surface-sterilization.
The hypothesis that the natural function of β-lactamase is the detoxification of penicillins has been tested by measuring the survival or growth of mixtures of micro- and magno-constitutive β-lactamase-producing Bacillus cereus in an environment containing naturally produced penicillins. The magno-constitutive strain had a clear survival advantage which was abolished or greatly reduced if minute quantities of purified β-lactamase were added, in which case the micro-constitutive seemed at a slight advantage.
- Accepted:
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