Enhanced photosynthetic output via dichroic beam-sharing

Microbial solar biofuels offer great promise for future sustainable food, fuels and chemicals but are limited by low productivities and a requirement for large land areas to harvest sunlight. A 71 % increase in combined photosynthetic activity was achieved by illuminating both Rhodobacter sphaeroides and Arthrospira (Spirulina) platensis from a single beam of simulated sunlight, divided using a dichroic mirror. Therefore, this technique is termed ‘dichroic beam-sharing’, in which the complementary action spectra of two different useful micro-organisms, belonging to green and purple groups, is exploited and allows a single beam of sunlight to be shared efficiently between separate photobioreactors. Because the action spectra of these two organisms are typical of large groups, this novel method could increase the productivity of photosynthetic micro-organisms in the production of diverse commodities.