Date of Graduation

12-2015

Document Type

Thesis

Degree Name

Master of Science in Biological Engineering (MS)

Degree Level

Graduate

Department

Biological and Agricultural Engineering

Advisor

Danille J. Carrier

Committee Member

Scott Osborn

Second Committee Member

Thomas A. Costello

Abstract

To produce fermentable sugars from lignocellulosic biomass feedstock, severe pretreatment conditions are needed (either high acid concentration, temperature, or retention times). High severities can produce toxic byproducts which inhibit enzymatic hydrolysis or fermentation. In order to reduce pretreatment severities (and thus increase enzyme and fermentation efficiency), the white-rot fungus Pleurotus ostreastus was seeded into square and round bales of Kanlow switchgrass (Panicum virgastum L.) and left in the field over a period of 9 month. The laccase producing fungus is believed to selectively degrade lignin, a common plant structural polymer, which can function as an enzymatic inhibitor. Samples were taken from different elevations within the bale 3, 5, 7, and 9 months after harvesting. These samples were treated at three different severities with liquid hot water pretreatment. Compositional analysis was done on the pretreated biomass, which was then enzymatically hydrolyzed with cellulases (endoglucanase and beta-glucosidase) after being washed. The yields (total recovered sugars over total present) were calculated and compared along five different variables: fungal treatment, storage time, pretreatment severity, sampling depth, and washing volumes. The results of the study found significant effects for sampling time (p=.0024) and pretreatment severity (p<.0001), but found no such significance in the effects of washing (p=.6624) and sampling depth (p=.0693). Results regarding the fungal inoculation were inconclusive, but provided the basis for the creation of experiments to be carried out in future work.

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