Cometabolism was used as a technique to accumulate biochemical products in high yield. As a result of cometabolism, cells of three bacterial species converted 98% of m-chlorobenzoate, 95% of 2,3,6-trichlorobenzoate, and 93% of the 3,5-dichlorocatechol provided to 4-chlorocatechol, 3,5-dichlorocatechol, and 2-hydroxy-3,5-dichloromuconic semialdehyde, respectively.