In method for producing L-lysine including  genetically altering E. coli, inventors failed to disclose best host strain to use and  further modification that enhanced production.

Ajinomoto Co. v. ITC, 2009-1081 (Fed. Cir. Mar. 8, 2010)

In a rare best mode case, the Federal Circuit confirmed invalidity of two patents for failure to disclose the best mode.  The claims at issue claimed methods of producing L-lysine with E. coli genetically engineered with mutations of either the gene responsible for inhibiting further lysine production once a certain amount has been produced or the gene responsible for  breaking down excess lysine.  Each claim had steps of cultivating the mutated microorganism to produce L-lysine and collecting the L-lysine.  The patents described preparing mutant strain having these modifications that were deposited in an international depository.  The patents did not describe, however, that these strains has two additional genetic modifications to encode an enzyme in the synthesis and to allow use of sucrose as a carbon source in the synthesis.  Because the claims were for “producing L-lysine,” and because these two additional, undisclosed features were part of the inventor’s contemplated best mode for carrying out the claimed process—producing lysine—the requirement to disclose best mode had not been met.

The patentee argued that “best mode” was limited to production of lysine by the claimed genetic mutations; however, the claimed invention was a process of making lysine by cultivating genetically altered E. coli, and this process was admittedly enhanced by the other, undisclosed features.  The inventors were obligated to disclose the preferred bacterial strain they used to practice the invention, as well as the undisclosed modification that allowed them to use sucrose.

Practice tip: There is no “gist of the invention” doctrine for best mode.