Thesis

Investigation of the fungi from Boiling Springs Lake, Lassen Volcanic National Park, CA for potential applications to lignocellulosic biofuels

In the pursuit of producing cleaner fuels, plant lignocellulose is a source of fermentable sugars that don’t compete with food production. Conversion of plant components, or lignocellulose, into biofuels typically requires hot and acidic pre-treatment conditions not suitable to most commercial fungal enzymes. In this work, I evaluated seven Ascomycota fungi associated with Boiling Springs Lake (BSL) in Lassen Volcanic National Park, a hot and acid environment, for utilization of lignocellulose material. Due to the conditions of BSL, I hypothesized these fungal isolates produce thermal/acidic stable enzymes. To test this, the fungi were screened for: growth on purified or natural components under hot, acid conditions; lignocellulose degradation genes with PCR; and, potential lignin degradation via a (per)oxidase assay. Growth analysis showed Acidomyces and Ochroconis growing >40 °C and pH <4; Aspergillus, Paecilomyces and Penicillium preferred cooler temperatures for acidic media but still grew above 40 °C; Phialophora only grew up to 27 °C under both acidic and neutral conditions; and Cladosporium showed a preference for cool, neutral conditions. The most promising material utilizers, Acidomyces, Ochroconis and Paecilomyces used cellobiose, xylan, pine and incense cedar needles for growth at 40 °C and pH 2. The remaining fungi used fewer materials. PCR results showed Acidomyces, Paecilomyces, and Ochroconis containing orthologs to known fungal lignocellulose degradation genes. Additionally, Acidomyces and Ochroconis showed extracellular (per)oxidase activity at 40 °C and pH 2. From these combined results, I concluded that Acidomyces, Ochroconis and Paecilomyces have potential for use in the pretreatment of lignocellulosic biofuels.

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