Codexis, a Redwood City, Calif.-based startup with oil giants Shell and Chevron among its backers, is in the business of so-called evolved biocatalysts: It takes a natural microbe or enzyme and tweaks the DNA sequences to create new variants, then searches for the variants best suited to development of new, potentially cheaper drugs (Pfizer used Codexis enzymes to produce Lipitor) and non-ethanol biofuels. This summer, the 7-year-old startup said it was looking for ways to apply this expertise to the emerging market for carbon capture technologies.