US researchers are finding that what goes for the work place, the playing field, and the home goes for getting the most out of fuel-producing yeasts: teamwork makes the dream work. Inspired by the give-and-take that enables the community of microorganisms found in lichens to thrive in a range of environments, the team paired photosynthetic bacteria with yeast strains to streamline the production of energy-dense fatty acids. That two-way interaction could point to new ways of making biofuels a more attractive alternative energy source.
Yeast are among the most industrious organisms on earth. Through the power of fermentation, these microorganisms can take sugar and turn it into clean-burning fuel. But even when genetically optimized to withstand high temperatures and boozy volumes of fuel production, yeasts must still be fed their sweet treat externally. That adds extra processing steps and drives up cost. So how can researchers slash the price of adding carbon to make biofuels? By outsourcing to an equally industrious business partner.
Yeasts and other fungi, it turns out, interact favorably with certain photosynthetic bacteria. In fact, many lichens, the often leafy growths found on trees and rocks, include co-habitating bacteria and fungi. These photosynthetic bacteria, called cyanobacteria, collect sunlight and carbon dioxide from the environment and convert it into a sugary meal. In turn, the fungus supplies minerals, nutrients, and protection from harsh environments. Motivated by this mutual arrangement, the research team paired bacteria engineered to secrete sugars with a strain of yeast that produced biofuel precursors and protected their cyanobacterial partners.
After optimizing the conditions for growing the yeast and bacterial cells together, the researchers observed the sustained production of fatty acids, up to 60% more than that generated by the bacteria alone. This boost in efficiency was attributed to the yeast’s ability to make these fatty acids more efficiently and stave off the damage to bacteria caused by free radicals in the environment.
More work is needed to further optimize the team’s artificial lichen system. But with the carbon supplied by photosynthesis, researchers now have a viable platform for sustainably producing biofuels from yeast—all made possible by mimicking one of nature’s most important partnerships.