Method for the production of cephalosporins

A method for the production of a cephalosporin of the formula:

• ##SPC9##
• wherein R is an unsaturated six-membered carbocyclic ring or five-membered heterocyclic ring residue which may have uncharged substituent(s);
• R.sup.1 hydrogen, hydroxy, or halogen;
• R.sup.2 is a hydrogen atom or an organic group which is bound through an oxygen, sulfur or nitrogen atom;
• COOR.sup.3 is an ester group which may be easily converted to COOH, which comprises reacting a derivative of an organic acid of the formula:
• ##EQU4## wherein R and R.sup.1 have the same meaning as defined above with 7-aminocephem-4-carboxilic acid ester of the formula:
• ##SPC10##
• wherein R.sup.2 and COOR.sup.3 have the same meaning as defined above in the presence of a culture or the enzyme containing processed matter of said culture of the microorganism of one of the genera Escherichia, Bacillus, Proteus and Pseudomonas which is able to synthesize a cephalosporin of the formula (I) from a derivative of the organic acid of the formula (II) and 7-aminocephem-4-carboxylic acid ester of the formula (III).