Comparison of glycine enhancement with cefoxitin induction of class 1 beta-lactamase production in Enterobacter cloacae ATCC 13047.
The presence of either glycine or cefoxitin in the growth medium resulted in an increase in the beta-lactamase activity of cultures of Enterobacter cloacae ATCC 13047. Although the beta-lactamases produced as a result of either glycine enhancement or cefoxitin induction were identical there were striking differences in the kinetics of beta-lactamase production. The increased production of beta-lactamase which resulted from enhancement by glycine occurred late in the growth cycle whereas, with cefoxitin induction, the maximum production of beta-lactamase occurred early in logarithmic-phase growth. After the peak activity was reached the beta-lactamase activity appeared to decline with both processes. However, the mechanism of the apparent fall in the intracellular beta-lactamase activity was different with glycine enhancement and cefoxitin induction. In glycine enhanced cultures the fall presumably was due to leakage of intracellular beta-lactamase into the culture medium whereas with cefoxitin induced cultures there was dilution of beta-lactamase activity by bacterial protein derived from an increase in cell numbers after the cessation of induction. High extra-cellular levels of beta-lactamase activity were observed in cultures enhanced by glycine, whereas little beta-lactamase activity was detected in the medium when the cultures were induced by cefoxitin. The findings demonstrate that there are considerable differences between glycine enhancement and cefoxitin induction, but a final mechanism common to both processes exists which results in the production of identical beta-lactamases by E. cloacae ATCC 13047.
Gatus
B J
BJ
Department of Microbiology, Prince of Wales Hospital, Randwick, NSW, Australia.
Bell
S M
SM
Jimenez
A S
AS
D002440:Cefoxitin / Q000494:pharmacology*; D002455:Cell Division / Q000187:drug effects; D004754:Enterobacter / Q000187:drug effects* / Q000201:enzymology; D004755:Enterobacteriaceae / Q000187:drug effects*; D004790:Enzyme Induction / Q000187:drug effects; D005998:Glycine / Q000494:pharmacology*; D007526:Isoelectric Point; D007700:Kinetics; D001618:beta-Lactamases / Q000096:biosynthesis* / Q000302:isolation & purification
D002440:Cefoxitin; D001618:beta-Lactamases; D005998:Glycine