The influence of different light sources and light intensity on mycophenolic acid (MPA) by Penicillium brevicompactum in batch culture was significant and demonstrated in this study. MPA batch cultures under various light sources including fluorescent light, red LED light (630 nm) and blue LED light (470 nm), were investigated in a light controlled photo-bioreactor. Results of cultures under fluorescent light indicated that optimal maximum cell density and maximum MPA concentration (P(max)) achieved at 1400 lux were 9.40 and 0.48 g L(-1), respectively. Results of culture under LED lights indicated that the optimal culture condition for cell growth was red LED light at 600 lux with cell yield, 0.88 g g(-1), while that for MPA formation was blue LED light at 600 lux with specific product yield, 0.056 g g(-1). Red LED light stimulated both cell growth and MPA formation; however, blue LED light inhibited cell growth but stimulated MPA formation. A novel two-stage LED light process has been successfully demonstrated to optimize MPA fermentation of P. brevicompactum, and the highest P(max) of 0.56 g L(-1) was achieved with 87% improvement as compared with that of the batch in the dark. (C) 2010 Elsevier Inc. All rights reserved.