The marine alga Nannochloropsis oceanica and the common soil fungus Mortierella elongata both produce oils that can be harvested to produce biofuels. When cultivated in the same environment, the algae combine with the fungi to form larger masses via bioflocculation. Harvested together, the organisms yield more oil than if When placed in the same environment, the algae (green) attach to the fungi (brown).Source: Zhi-Yan Du and Igor Houwat; Michigan State University-DOE Plant Research Laboratory, 2018they were cultivated and harvested each on their own.

The algae are fed with ammonium, a nitrogen source that algae can quickly use for growth. The ammonium supply is controlled so that algae produce the maximum cell density and automatically enter nitrogen starvation. The closely monitored nitrogen regimen can boost oil production and lower costs.

Because the system doesn't rely on fossil fuels, researchers say it is sustainable. The fungi grow on sewage or food waste, while the algae grow in sea water. The cost of the biofuel production is also lower because of the low-cost collection method, using mesh and other tools. The method is also potentially easier to scale relative to other biofuel routes, as the organisms are wild strains that have not been genetically modified. They pose no risks of infecting any environment they come in contact with.

The study conducted by Michigan State University researchers is published in Biotechnology for Biofuels.