Syngenta and Diversa create partnership to discover enzymes for second-generation biofuels

Syngenta and Diversa Corporation announced today a new 10-year research and development partnership focused on the discovery and development of a range of novel enzymes to convert pre-treated cellulosic biomass economically to mixed sugars – a critical step in the process of 'second generation' ethanol production.

The new agreement allows Diversa to independently develop and commercialize fermentation-based enzyme combinations from its proprietary platform. Syngenta will have exclusive access to enzymes from Diversa’s platform to express in plants for enhanced cost-effective production.

Converting ligno-cellulosic biomass to biofuels requires breakthrough developments in three areas:

1. chemical preparation of the cellulosic biomass (pre-treatment)
2. conversion of pre-treated cellulosic biomass to fermentable sugars by combinations of enzymes (saccharification)
3. the development of novel micro-organisms to ferment the sugars to ethanol or other fuels (fermentation)

Developing cost-effective enzyme systems is essential to economically converting biomass to biofuels:
ethanol :: biomass :: bioenergy :: biofuels :: energy :: sustainability :: enzymes :: cellulosic ethanol :: biotechnology ::

Under the terms of the new agreement, which replaces the companies’ prior agreement, Syngenta will pay Diversa €12.3/US$16 million of guaranteed research funding in the first two years. Diversa is eligible to receive certain milestone and royalty payments aligned to product development success:

Previous breakthrough
As one result of their earlier partnership, Syngenta, a global agribusiness and third in the high-value commercial seeds market, is developing a genetically modified strain of corn that expresses high levels of alpha amylase—a thermal-tolerant digestive enzyme developed by Diversa that turns the corn’s starch into sugar for ethanol.The engineered plants are designed to reduce costs by eliminating the need for mills to add liquid enzymes. The Amylase-T seeds do not increase the yield, rather they make corn easier to process.

Amylase is a digestive enzyme (present in saliva, for example) that breaks down long-chain carbohydrates (such as starch) as an initial step in the production of ethanol from grain starch.

Very broadly, in this type of production, corn or starchy grain is ground into flour (“meal”), which is then slurried with water to form a mash. Enzymes are added for the conversion of starch to sugar, the whole mash is processed in a high-temperature cooker and then transferred to fermenters where yeast is added and the conversion of sugar to ethanol and CO2 begins.

The starch is usually heated at around 105°C or higher in the presence of thermostable alpha amylase, and then liquefied further at a lower temperature (around 90ºC). The high temperatures help reduce bacteria levels in the mash (high bacteria levels reduce yield).

Another key factor in the outcome of the process besides temperature is pH.

The pH is a measure of the acidity or alkalinity of a solution expressed on a scale of 1-14. Neutral is pH 7, pH 1-7 is acid, and pH 7-14 is alkaline. Yeast will grow only in a slightly acid solution (and the growth of harmful bacteria is further retarded by the slight acidity).

Conventional alpha-amylase enzymes, however, function best in a slightly alkaline environment.

As a result, ethanol producers spend time and material managing the pH of the mash to optimize the different stages of the process. And as a further result, producers have been seeking an enzyme that works well in a lower pH environment for years. As late as 2000, low pH-high temperature amylases were one of the top research requests from the industry.

The new Diversa research “Ultra-Thin” enzyme appears to meet that need. Capable of operating robustly at pH 4.5—the same pH of the production process—it reduces the cost associated with managing the mash pH.

Picture: modified Amylase enzyme.