The transporter CefM involved in translocation of biosynthetic intermediates is essential for cephalosporin production.

Targeted inactivation of cefM by gene replacement showed that it is essential for cephalosporin biosynthesis, and the disrupted mutant accumulates a significant amount of penicillin N, is unable to synthesize deacetoxy-, deacetyl-cephalospor in C and cep HalosporIn C and shows impaired differentiation into arthrospores.