The algal trophic mode affects the interaction and oil production of a synergistic microalga-yeast consortium.

The use of non-food feedstocks to produce renewable microbial resources can limit our dependence on fossil fuels and lower CO2 emissions. Since microalgae display a virtuous CO2 and O2 exchange with heterotrophs, the microalga Chlamydomonas reinhardtii was combined with the oleaginous yeast Lipomyces starkeyi, known for their production of oil, base material for biodiesel. The coupled growth was shown to be synergistic for biomass and lipid production. The species were truly symbiotic since synergistic growth occurred even when the alga cannot use the organic carbon in the feedstock and in absence of air, thus depending entirely on CO2-O2 exchange. Since addition of acetate as the algal carbon source lowered the performance of the consortium, the microbial system design should take into account algal mixotrophy. The mixed biomass was found be suitable for biodiesel production, and whereas lipid production increased in the consortium, yields should be improved in future studies.