For the production of cis,cis-muconic acid via biocatalytic conversion reactions from a toxic cosubstrate, benzoic acid, we developed a fed-batch process using computer-controlled DO-stat feeding. The mutant strain of Pseudomonas putida BM014 produced cis,cis-muconic acid with high conversion yield. More than 32 g/l of cis,cis-muconic acid was accumulated in 40 h including the initial batch and constant-feeding periods and a productivity value more than 2.2 g/(l . h) was achieved.