Submitted to: American Society for Microbiology Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: May 20, 2002
Publication Date: May 22, 2002
Citation: Stevenson, D.M., Weimer, P.J. 2002. Isolation and characterization of a trichoderma strain capable of fermenting cellulose to ethanol [abstract].American Society for Microbiology Annual Meeting. p. 350. Technical Abstract: The direct fermentation of cellulosic biomass to ethanol has long been a desired goal, and while numerous fermentative bacteria can carry out this process, there are few reports of fungi with this capability. To this end, we screened the environment for fungal strains capable of this conversion when grown on minimal medium. One strain, identified as a member of the genus Trichoderma and designated strain 40:10:10, was found that initially produced about 0.4 g ethanol/L. This strain cannot grow on any substrate under anaerobic conditions, but can anaerobically ferment microcrystalline cellulose or several sugars to ethanol. When the fermentation was carried out in submerged culture in minimal medium, ethanol accumulation was eventually increased to 2 g/L through strain selection and the use of a vented fermentation flask. The highest levels of ethanol, ~5.0 g/L, was obtained by the fermentation of glucose. Little ethanol was produced by the fermentation of xylose, although other fermentation products such as succinate and acetate were observed. This strain was also found to aerobically utilize a wide range of carbon sources. In addition, auxotrophic mutants for arginine, inosine, and adenine/hypoxanthine were generated and used to demonstrate parasexuality by complementation between auxotrophs and between morphological mutants. The ability of this strain to use a wide variety of carbohydrates (including crystalline cellulose) combined with its minimal nutrient requirements and the availability of a genetic system suggests that the strain merits further investigation of its ability to convert biomass to ethanol.