Microbes found in the digestive tract of goats, sheep, and other large herbivores offer attractive enzyme platforms for breaking down grasses and other plants into the building blocks for biofuels.
Industry is exploring strategies to more effectively turn grasses, wood, and other types of biomass into fuel or chemicals. Because the matrix of complex molecules found in plant cell walls—lignin, cellulose, and hemicellulose—is difficult to break down using biological methods, costly pretreatments with heat or chemicals are necessary.
The discovery of new, highly effective biomass-degrading enzymes in fungi could accelerate the development of a process to convert plant feedstocks into fermentable sugars without pretreatment, potentially leading to more efficient conversion of raw biomass to biofuels and biobased products.
Scientists have long known that anaerobic fungi living in the guts of herbivores play a significant role in helping those animals digest plants.
However, culturing these fungi in the lab is difficult because they cannot survive in the presence of oxygen and must be grown in sealed containers.
A research team led by Michelle O’Malley at the University of California, Santa Barbara, isolated three species of these fungi in feces from goats, horses, and sheep. The enzymes expressed by these fungi work together to break down crude, untreated plant biomass. The fungi adapt their enzymes to the different kinds of plant materials eaten by these animals so that wood, grass, or agricultural waste all can be efficiently digested.
Each of the fungi studied was found to contribute in a characteristic way, tailoring their combined action to the particular type of biomass being digested.
These findings could help in identifying distinctive enzymes from other anaerobic gut fungi, with potential applications for biomass processing and sustainable biofuel production.
Source: U.S. Department of Energy, Office of Science