How Scientists Could Expand The Menu Of Biofuel-Making Microbes

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Using a highly advanced microscope, researchers just figured out a method to identify new bacteria capable of producing biofuel.

Specifically, the scientific team was looking for bacteria that create and store up large amounts of triacylglycerols (TAGs) — oils that are the direct building blocks for biodiesel. They focused on a strain of microbe called Streptomyces which is found in soil. Using an incredibly high-resolution microscope the team was able to identify which forms of Streptomyces store up healthy amounts of the oils and which do not. They also hope the methodology can be expanded to identify other strains of microbes as well.

Broadly speaking, traditional biofuels — which are made by transforming the simple sugars found in corn or soy into alcohols like ethanol — face two intersecting problems. One, the feedstocks also double as human food, so the demand for biofuels can drive up food prices. Two, that demand can also drive more agriculture and conversion of natural land to farm fields, which undoes a lot of biofuels’ advantage in terms of carbon emissions.

The route around these problems is to rely on feedstocks like crop leftovers, wood chipping, grass, and other forms of plant waste. That avoids competing with food sources, and limits feedstocks to waste from agricultural and industrial activities that would’ve gone on anyway. The challenge is those feedstocks are made out of tougher material, and are harder to convert into usable fuel. Which is what makes them advanced biofuels rather than the traditional variety.

Mainly, that tough material consists of cellulose and lignin. The cellulose is a complex cougar that can be broken down into simpler sugars and then converted to alcohol — cellulosic ethanol. But the lignin can also be broken down into the triacylglycerols that lead to biodiesel, another form of advanced biofuel. And since most plastics are oil-based, advances in the production of triacylglycerols and similar oils mean advances in the production of bioplastics as well.

That’s where Streptomyces comes in. Scientists have been looking into its ability to convert lignin into oils for a while — switching on the genes that initiate the conversion process, and hoping to scale that knowledge into wider genetic engineering of microbes to produce biofuels. Streptomyces is also widely used in the pharmaceutical industry already, so a lot of the practical and knowledge and infrastructure for growing the microbe at commercial scale is already in place.

With the arrival of this new identification metrology, scientists can hopefully expand their manna of potential microbes even further, and continue pushing forward along all of these paths to sustainable fuels.