The influence of adipate concentration and dissolved oxygen on production of adipoyl-7-aminodeacetoxycephalosporanic acid (ad-7-ADCA) by a recombinant strain of Penicillium chrysogenum expressing the expandase gene from Streptomyces clavuligerus was studied in glucose-limited continuous cultures. Operating conditions were maintained constant but the adipate and dissolved oxygen concentrations (DOC) were varied separately in a range from 1 to 37.5gl(-1) and from 2% to 125% air saturation (%AS), respectively. The total beta-lactams specific productivity, r(ptotal), was not significantly changed for adipate concentrations from 5 to 25gl(-1), but the flux towards an unknown by-product decreased as the adipate concentration increased. Investigations at different DOC showed that r(ptotal) was stable around 18 micro molgDW(-1)h(-1) for DOC being in the range from 15 to 125%AS. When DOC was decreased from 15 to 7%AS, r(ptotal) increased to 25 micro molgDW(-1)h(-1), mainly due to a two-fold increase in the adipoyl-6-aminopenicillanic acid (ad-6-APA) specific productivity.