Comments regarding Dr. Nancy Ho’s Yeast

by Colleagues in Industry


Quite a few American and foreign ethanol producers and potential ethanol producers have tested the Purdue yeast, and all of them were quite impressed with the yeasts’ performance.  The following are excerpts written by industrial colleagues commenting on these yeasts and her efforts.


Dr. Charles A. Abbas

Director of Yeast and Renewable Research, Archer Daniels Midland Corp.

Oct 25, 2002


Dear Dr. Ho:


Thank you for allowing us to conduct fermentation research using your recombinant yeast. ….. We have successfully tested your organism on the mixed-sugar media generated from corn fiber.  Your (the Purdue) organism has been the most promising of all the non-recombinant and recombinant organisms that we tested under the specific parameters of our tests. The fermentation media was high in inhibitory compounds, including acetic acid, hydroxymethyl furfural, and furfural...


Mr. Larry W. Denny
President, Biomass Processing Technology, Inc

...Your accomplishment ranks as the most significant single accomplishment for the exploitation of biomass...

Dr. Robert E. Lumpkin
Vice President, Swan Biomass Company

...The development of the recombinant glucose/xylose co-fermenting yeasts was a technical breakthrough by Dr. Ho. For years, other microbiologists attempted to exploit a different, more direct route to engineering yeast to ferment xylose and glucose simultaneously. They all failed. Dr. Ho found a more elegant, indirect approach, and has been able to make it work despite some theoretical objections by her peers. She has had to overcome a great deal of skepticism about her approach in the academic community to secure the funding for research.

The unique technology used to create LNH can also be used to create engineered yeasts that ferment sugars to products other than ethanol. At the present time, Dr. Ho is focusing on ethanol production, and has been unable to divert resources to other products. However, there is no reason that organisms producing a variety of industrious-important chemicals cannot be pursued in the future using the techniques discovered and patented by Dr. Ho.

I have been selecting and sponsoring university-based research programs for major oil companies for over 25 years, and have worked with many others in industry, both in my own company and in others, who utilized university research. Dr. Ho's work is among the very best from a scientific standpoint, and far and away the best from an economic standpoint.  The occasional spectacular success like Dr. Ho's is what insures continued private sector support for academic research.


Mr. Robert Benson
Vice President, R&D/Technical Service, Tembec Chemical Products Group, Canada

...As you know our industrial alcohol plant ferments spent sulfite liquor (wood hydrolysates) with Saccharomyces cerevisiae. This allows us to produce 15M liters per year of high quality ethyl alcohol. We could increase our production by 30% if we could ferment the xylose sugar present in our liquor. We have been looking for more than 15 years for a  xylose fermenting yeast, which can survive in spent sulfite liquor.

We have evaluated many native and genetic recombinant strains, which were ineffective. To date other laboratories using genetic engineering techniques have been unsuccessful in their attempts to ferment xylose in our plant waste streams. In contrast your yeast has provided exciting results. Although our studies are not complete we continue to believe that your genetic engineering work provides the only real chance of achieving pentose fermentation on an industrial scale...

Dr. Ting Carlson
Sr. Research Scientist, Cargill North American Corn Milling

...Dr. Ho is one of the most persistent scientists I know who over the past 15 years worked on a very challenging research topic on engineering yeasts to ferment pentose sugars. She has demonstrated that old fashion hard work does pay off even in science and constructed the only pilot-scale tested glucose/xylose fermenting recombinant yeast on wood hydrolysates.

Generally, laboratory constructed recombinant microbes tend to fail in an industrial production condition, either from the lack of genetic stability or from the lack of tolerance to real- life fermentation substrates. In the case of biomass conversion to ethanol, xylose containing wood hydrolysates is extremely toxic to microbes due to the presence of wood extractive impurities. Dr. Ho anticipated and addressed these issues by engineering a very robust yeast strain and made it readily usable for industries.

Dr. Ho's accomplishment in this area is significant as it relates to our country's need to be energy self- sufficient. Due to her persistence, we now have an option in economically converting woody biomass to ethanol...