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Investigation of solid-state fungal pretreatment of Miscanthus for biofuels production

Vasco Correa, Juliana
http://orcid.org/0000-0002-5762-5015
http://rave.ohiolink.edu/etdc/view?acc_num=osu1500588568497253

Abstract Details

2017, Doctor of Philosophy, Ohio State University, Food, Agricultural and Biological Engineering.
Lignocellulosic biomass is an abundant source of renewable energy, but its high recalcitrance to biodegradation needs to be overcome to allow its conversion into biofuels. Thus, pretreatment of the lignocellulosic feedstock is usually required. Fungal pretreatment using white rot fungi is an alternative process to traditional thermo-chemical pretreatments that degrades lignin and enhances the enzymatic digestibility of the lignocellulosic biomass. Fungal pretreatment can be performed in solid-state at low temperature, without added chemicals such as strong acids or bases, and no wastewater is generated. However, in comparison with traditional pretreatments, disadvantages such as long residence times, low yields, and feedstock sterilization requirements make it challenging to implement. This work investigates the fungal pretreatment of non-sterile biomass with the white rot fungus, Ceriporiopsis subvermispora, for the production of biofuels using the dedicated energy crop Miscanthus × giganteus. For this purpose, solid-state fungal pretreatment of non-sterile Miscanthus was performed in batch using Miscanthus previously colonized with the fungus as inoculum. The process enhanced the enzymatic digestibility of Miscanthus by 3- to 4-fold over that of untreated Miscanthus after 21 days of incubation time. The finished material from this non-sterile pretreatment was used as inoculum for two more generations in a sequential fungal pretreatment process. A propagation of indigenous fungi that outcolonized C. subvermispora was observed through the generations, showing that sterilization is a required step for the stability and reproducibility of fungal pretreatment. The changes in composition and structure of Miscanthus after fungal pretreatment were compared with those in corn stover, hardwood, and softwood. Fungal pretreatment increased the enzymatic digestibility of hardwood, softwood, and Miscanthus by 2 to 4.5-fold; however, it was not effective for corn stover. Also, fungal pretreatment was effective for Miscanthus harvested in winter or spring, but not for green Miscanthus harvested in fall. Therefore, fungal pretreatment with C. subvermispora showed differential effects that were feedstock-dependent. Fungal pretreated Miscanthus was used for the production of biogas via solid-state anaerobic digestion, and an increase of 25% in specific methane yield was obtained compared to the untreated Miscanthus. Fungal pretreated Miscanthus was also used for the production of fermentable sugars through enzymatic hydrolysis with commercial hydrolases for butanol production. Results indicated that fungal pretreatment with C. subvermispora does not produce significant amounts of lignocellulosic derived microbial inhibitory compounds that have been shown to inhibit butanol fermentation with Clostridium beijerinckii; thus, it does not require detoxification and/or washing after pretreatment. A techno-economic analysis of the process to produce fermentable sugars from Miscanthus using fungal pretreatment showed that the process is not feasible at full cellulosic biorefinery scale due to the high capital cost caused by the long residence time, the low bulk density of the material, and the low sugar yields.
Ajay Shah (Advisor)
Thomas Mitchell (Committee Member)
Thaddeus Ezeji (Committee Member)
Fred Michel (Committee Member)
268 p.
Agricultural Engineering; Engineering; Environmental Engineering
Biomass; pretreatment; fungal pretreatment; biological pretreatment; white rot fungi; Ceriporiopsis subvermispora; microbial community; Miscanthus; anaerobic digestion; butanol; techno-economic analysis

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Citations

  • Vasco Correa, J. (2017). Investigation of solid-state fungal pretreatment of Miscanthus for biofuels production [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1500588568497253

    APA Style (7th edition)

  • Vasco Correa, Juliana. Investigation of solid-state fungal pretreatment of Miscanthus for biofuels production. 2017. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1500588568497253.

    MLA Style (8th edition)

  • Vasco Correa, Juliana. "Investigation of solid-state fungal pretreatment of Miscanthus for biofuels production." Doctoral dissertation, Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1500588568497253

    Chicago Manual of Style (17th edition)

osu1500588568497253
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