The researchers have already created a strain of Rhodococcus that can eat a mix of two types of sugars, glucose and xylose. Once scientists have found a way to break down cellulosic biomass into simpler sugars, the ability to use more than one will simplify the production process. “They are not like wimpy E. coli that can’t use different sugars simultaneously,” says Sinskey. “These bacteria gobble them up.” The researchers have also engineered strains that can feed on glycerol, which is a waste product in the production of biodiesel.
Sinskey and his team hope to develop better ways of isolating the lipids from bacteria at a commercial scale, perhaps via additional genetic engineering. For example, altering production of a specific protein encourages the lipids to aggregate into balls, called lipid bodies, which makes the molecules easier to recover. “Ideally, we want to develop a way to make the lipid body pop out of the cell,” says Sinskey.
It’s not yet clear how long it will take to create a process that is efficient enough for commercial production. “I don’t think I’m far behind lots of companies that have lots of publicity in this area,” says Sinskey. “I think in two to three years I will have a robust process.”
Sinskey previously developed a way to make polymers from bacteria, founding a bioindustrial company called Metabolix in the early 1990s. A $300 million plant that will produce the company’s biodegradable plastic is slated to begin operations later this year in December, as part of a joint venture with agricultural giant ADM.