The $1.5 billion-a-year company, which traces its roots to a 1925 insulin lab, received a high-profile plug two weeks ago from the Gigaton Throwdown Initiative, a clean-energy brainstorming network linking investors, entrepreneurs, business leaders and policy makers and established by Spring Ventures founder Sunil Paul, a clean-tech venture capitalist. The group pointed to enzymes as a promising climate mitigation technology with the potential for scalable growth.