Genetic and biochemical characterization of the chromosome-encoded class B beta-lactamases from Shewanella livingstonensis (SLB-1) and Shewanella frigidimarina (SFB-1).
OBJECTIVE
To determine the beta-lactamase gene content of beta-lactam-susceptible psychrophilic gram-negative bacilli, Shewanella frigidimarina and Shewanella livingstonensis, isolated from a marine environment.


METHODS
Beta-lactamase genes were cloned, sequenced and expressed in Escherichia coli. Kinetic parameters were determined using purified enzymes.


RESULTS
Metallo-beta-lactamases SLB-1 and SFB-1 were identified from S. livingstonensis and S. frigidimarina, respectively, sharing 65% amino acid identity and being distantly related to other Ambler class B beta-lactamases (40 and 36% amino acid identity with GIM-1 and IMP-1 from Pseudomonas aeruginosa, respectively). SLB-1 had an EDTA-inhibited and broad-spectrum beta-lactam hydrolysis profile, whereas SFB-1 did not hydrolyse cephalosporins, with activity being weakly inhibited by EDTA and dipicolinic acid.


CONCLUSIONS
This work provides further evidence that psychrophilic bacterial species may constitute a reservoir of beta-lactam resistance genes.
Poirel
Laurent
L
Service de Bactériologie-Virologie, Hôpital de Bicêtre, Assistance Publique/Hôpitaux de Paris, Faculté de Médecine Paris-Sud, 78 rue du Général Leclerc, 94275 Le Kremlin-Bicêtre Cedex, France.
Héritier
Claire
C
Nordmann
Patrice
P
D000595:Amino Acid Sequence; D002876:Chromosomes, Bacterial / Q000235:genetics*; D003001:Cloning, Molecular; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D017422:Sequence Analysis, DNA; D020592:Shewanella / Q000145:classification / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D018440:beta-Lactam Resistance; D001618:beta-Lactamases / Q000235:genetics* / Q000378:metabolism*; D047090:beta-Lactams / Q000494:pharmacology*
D047090:beta-Lactams; D001618:beta-Lactamases