Characterization of extracellular beta-lactamases from penicillin G-resistant cells of Streptococcus thermophilus

Chirica L., Guray T., Gurakan G. C. , Bozoglu F.

JOURNAL OF FOOD PROTECTION, vol.61, no.7, pp.896-898, 1998 (Peer-Reviewed Journal) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 61 Issue: 7
  • Publication Date: 1998
  • Doi Number: 10.4315/0362-028x-61.7.896
  • Journal Indexes: Science Citation Index Expanded, Scopus
  • Page Numbers: pp.896-898


In this study, biochemical properties of two extracellular beta-lactamases produced by penicillin-resistant Streptococcus thermophilus cells were investigated. Both beta-lactamases showed specificity for penicillins but not for cephaloridins. The p-lactamases exhibited different affinities for penicillin G. The one with the higher molecular weight (F1) had a K(m) value of 3.44 mu M and a V(max), value of 8.33, mu mol/min/mg of protein, whereas the beta-lactamase with the lower molecular weight (FII) had a K(m) value of 4.76 mu M and a V(max) value of 3.13 mu mol/min/mg of protein. Both beta-lactamases were inhibited by iodine, copper sulfate, and iron sulfate but not by EDTA. The optimal pH ranged between 6 and 7. and the optimal temperatures were between 40 and 45 degrees C for both enzymes.