May 1, 1976

Formation of beta-lactamase in Bacteroides fragilis: cell-bound and extracellular activity

Antimicrobial Agents and Chemotherapy
B OlssonT Wadström

Abstract

Nine strains of Bacteroides fragilis were cultivated in stirred fermentors and tested for their ability to produce beta-lactamase. There was a correlation between formation of beta-lactamase and high values of the minimal inhibitory concentration against beta-lactam antibiotics. B. fragilis strain B70 was used for optimizing the production of beta-lactamase. The highest bacterial yield was obtained in a proteose peptone-yeast extract medium. Optimal conditions for growth and beta-lactamase production were obtained at 37 C and pH 7.0. The beta-lactamase was released into the surrounding medium during the growth period to about 50%. Osmotic shock released about 20% of the total activity, and remaining activity was found in the cytoplasmic fraction. Substrate profile studies on four beta-lactamase-producing strains showed that the enzymes were mainly cephalosporinases. They are inhibited by cloxacillin, p-chloromercuribenzoate, and iodine. Analytical isoelectric focusing in polyacrylamide gel gave an isoelectric point of 4.9 +/- 0.2 for three of the strains and 5.6 +/- 0.2 for one. Comparison with beta-lactamases from aerobic gram-negative species with regard to isoelectric points showed no similarities. Also the molecular weight ...Continue Reading

Mentioned in this Paper

Monobactams
Bursera fragilis
Polyacrylamide Gels
Extracellular
Enzymes, antithrombotic
Iodine, Homeopathic preparation
Iodine
Bacteroides Infections
Beta-Lactamase
Bacteroides fragilis

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