Anthocyanin production by strawberry cells depends not only on light intensity but also on the light/dark cycle operation with hour- or second-scale periods. These findings are useful fur designing and operating photobioreactors for enhanced anthocyanin production. Intermittent illumination with a second-scale period produces the same amount of anthocyanin as continuous light, suggesting that the light intensity distribution within a photobioreactor does not cause suppressed production. In the hour-scale cycle, continuous light operation enhanced anthocyanin production more than the light/dark cycle process. (C) 2000 Elsevier Science Inc. All rights reserved.