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Oral Presentation 1-04
Microbial Pretreatment of
Biomass -- Potential for Reducing the Severity of Thermochemical Biomass
Pretreatment Fred A. Keller, Jenny E. Hamilton,
Quang
A. Nguyen1 1National Renewable Energy
Laboratory 1617 Cole Boulevard
Golden, CO 80401 E-mail: quang_nguyen@nrel.gov Typical
pretreatment requires high energy (steam and electricity) and corrosion
resistant, high-pressure reactors. Our
literature assessment suggests that fungal pretreatment could potentially lower
the severity requirements of acid, temperature and time. These reductions in severity are also
expected to result in less biomass degradation and consequently lower
inhibitors. In
the pulp industry, fungal pretreatment of wood chips, generally called
"seasoning", has been used to reduce pulping chemical
requirements. Mechanical pulp refining
energy is reduced by as much as 47% and 37% by mild, fungal pretreatment of
hardwoods and softwoods, respectively.
Furthermore, potential advantages of fungal pretreatment of agricultural
residues, such as corn stover, are suggested by its effectiveness in improving
the in vitro and in vivo digestibility of many types of forage fiber and
agricultural wastes. For example, the digestibility of Bermuda grass has been
improved 80% by fungal pretreatment in only 72 h. The
potential of fungal pretreatment of agricultural residues, such as corn stover,
is confirmed by our laboratory tests.
Our preliminary tests show a 3- to 5-fold improvement in enzymatic
cellulose digestibility of corn stover after pretreatment with Cyathus stercoreus; and a 10- to
100-fold reduction in shear force needed to obtain the same shear rate of 3.2
to 7 rev/sec, respectively, after pretreatment with Phanerochaete chrysosporium. These impressive improvements suggest that significant
reduction in the severity of steam pretreatment could be realized. Furthermore,
integrating fungal pretreatment into feedstock preparation and storage of
biomass-to-chemical processes may enhance the overall process.
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