BACKGROUND: Lactobionic acid production from dairy waste using Psedomonas taetrolens has gained rapid momentum as it is an economically feasible and environmentally friendly approach. Although photoreceptors have been identified in P. taetrolens, the effect of light on the production of lactobionic acid has not been investigated. This research successfully demonstrates the influence of light on lactobionic acid production by P. taetrolens from cheese whey. RESULTS: Experimental results indicated that while red light promoted both cell growth and lactobionic acid production, blue light could only promote cell growth. X-max and P-max increased from 12.78 to 15.83 g L-1 and 17.4 to 24.5 g L-1, respectively, under red LED light at 500 lux. On the other hand, X-max increased from 12.78 to 15.18 g L-1, but P-max decreased from 17.4 to 15.4 g L-1 under blue LED light at 100 lux. A novel two-stage LED photo-bioreactor process was successful in reducing fermentation time by 24 h compared with that of the photo-bioreactor under red LED light at 500 lux. CONCLUSION: It is proposed that light of varying wavelengths and intensities can be used as modulator to enhance lactobionic production by P. taetrolens using cheese way. (C) 2017 Society of Chemical Industry