The microbe
Clostridium thermocellum (stained green), seen growing on a piece of poplar
biomass,
is among several
microorganisms recently evaluated in a BioEnergy Science Center comparative
study. Image by
Jennifer Morrell-Falvey, Oak Ridge National Laboratory.
(January 15, 2016) Researchers
at the Department of Energy’s BioEnergy Science Center are looking beyond the
usual suspects in the search for microbes that can efficiently break down
inedible plant matter for conversion to biofuels. A new comparative study from
the Oak Ridge National Laboratory-based center finds the natural abilities of
unconventional bacteria could help boost the efficiency of cellulosic biofuel
production.
A team of researchers from five institutions analyzed the
ability of six microorganisms to solubilize potential bioenergy feedstocks such
as switchgrass that have evolved strong defenses against biological and
chemical attack. Solubilization prepares the plant feedstocks for subsequent
fermentation and, ultimately, use as fuel. The paper, published in
Biotechnology for Biofuels, is the most comprehensive comparative study of its
type to date.
“Starting with nature’s best biomass-solubilizing systems
may enable a reduction in the amount of nonbiological processing required to
produce biofuels,” said ORNL coauthor Brian Davison. “We’re asking the question
– what are nature’s best biocatalysts?”
Their analysis demonstrated that under carefully controlled
conditions, a microbe called Clostridium thermocellum is twice as effective as
fungal enzymes used by industry today. The researchers also tested the
different microbes’ performance with minimal pretreatment of the plant
materials, indicating it may be possible to reduce or eliminate use of heat and
chemicals that make the feedstock accessible to biological processing.
“Eliminating both enzyme addition and conventional
pretreatment is a potential game-changer,” said Dartmouth engineering professor
Lee Lynd, the study’s corresponding author.