The ‘188 patent covers a recombinant microbial host cell that uses a particular biosynthetic pathway to produce isobutanol. The ‘889 patent focuses on a method of producing isobutanol from a recombinant yeast microorganism. The claims of the two Butamax patents are currently under reexamination at the US Patent and Trademark Office (USPTO), which has declared them unpatentable.
Gevo believes it does not infringe any valid claims, and reported that it will continue to produce and sell isobutanol worldwide and into all markets. Butamax said it will continue its lawsuit and has asserted six other patents against Gevo, three of which are set to go to trial in the summer.