Abstract: A cephalosporinase testing agent comprising a cephalosporin antibiotic, a penicillinase inhibitor in an amount of 20% by weight or less based on the weight of the cephalosporin-antibiotic, and a pH indicator which may be bromcresol purple is provided. A cephalosporinase producing bacteria can be judged by smearing a sample containing bacteria to be tested on the testing agent and observing the color tone change. According to this agent, cephalosporinase-active penicillinase producing bacteria are judged cephalosporinase-negative owing to the action of the penicillinase inhibitor, which may be clavulanic acid. Therefore, since only cephalosporinase producing bacteria are judged cephalosporinase-positive, this agent enables error free judgment.

Abstract: A safe and versatile recombinant DNA cloning vector having at least two functionally different replication origins selected independently from the group consisting of a replication origin functional in Bacillus subtilis, a replication origin functional in Escherichia coli and a replication origin functional in Pseudomonas aeruginosa, and at least one DNA segment which provides resistance against at least one antibiotic after introduction into susceptible host cells. The origin for replication origin functional in Bacillus subtilis can be a restriction fragment of a plasmid of Gram positive bacteria, and that Escherichia coli or Pseudomonas aeruginosa can be a restriction fragment of a plasmid of Gram negative bacteria, e.g. a restriction fragment of plasmids pMS 140-1 or pMS 71.