1-42: Microoganisms to produce ethanol directly from plant fiber

Microorganisms that live in the cow’s rumen orchestrate the fastest biological degradation of biomass on earth.  For example, a strain of Ruminococcus albus readily degrades ligno-cellulose without pretreatment to produce acetate and ethanol. The objective of this study was to isolate fiber-digesting microorganisms from the rumen that produce ethanol to a high concentration.  Rumen fluid was collected from a fistulated cow and enriched for fiber digesting microbes by incubating in media with timothy grass hay as the main substrate.  Every 3 to 5 days a portion of the culture was transferred to new media.  For some enrichments, the media contained 6% or 10% ethanol by volume.  Individual strains that grew on Avicel,  filter paper or cellobiose were isolated on agar from diluted enrichments.  Several isolates could digest various types of biomass (e.g. cellulose, hemicellulose, grass) and convert it directly to ethanol.  Microbial cultures from the rumen converted 1% cellobiose to 0.5% ethanol increasing ethanol concentration from initial 6.0% to more than 6.5%.  A second addition of cellobiose further increased ethanol to more than 7.0%.  The 16s-rDNA sequences of strains that converted cellobiose to ethanol at high concentration were > 97% homologous with Clostridium bifermentans, C. sordelli, C. sporogenes, Enterococcus casselflavus, E. muntii, E. sangunicola, E. faecium, E. lactis, Pediococcus acidilactici, Lactobacillus mucosae, or Staphylococcus epidermidis.  Microorganisms like these produce ethanol directly from waste biomass or grass (patent pending).  The biomass is sterilized with heat and pressure and then simultaneously digested and fermented to ethanol.