Use of process design and metabolic engineering to enhance bioconversion of lignocellulosic biomass and glycerol to biofuels

Use of process design and metabolic engineering to enhance bioconversion of lignocellulosic biomass and glycerol to biofuels

Bibliographic Details
Main Author: Agu, Chidozie Victor, Agu
Language:English
Published: The Ohio State University / OhioLINK 2016
Subjects:
Agriculture
Animal Sciences
Biology
Biochemistry
Microbiology
Molecular Biology
Online Access:http://rave.ohiolink.edu/etdc/view?acc_num=osu1480590331055825
id ndltd-OhioLink-oai-etd.ohiolink.edu-osu1480590331055825
record_format oai_dc
collection NDLTD
language English
sources NDLTD
topic Agriculture
Animal Sciences
Biology
Biochemistry
Microbiology
Molecular Biology
spellingShingle Agriculture
Animal Sciences
Biology
Biochemistry
Microbiology
Molecular Biology
Agu, Chidozie Victor, Agu
Use of process design and metabolic engineering to enhance bioconversion of lignocellulosic biomass and glycerol to biofuels
author Agu, Chidozie Victor, Agu
author_facet Agu, Chidozie Victor, Agu
author_sort Agu, Chidozie Victor, Agu
title Use of process design and metabolic engineering to enhance bioconversion of lignocellulosic biomass and glycerol to biofuels
title_short Use of process design and metabolic engineering to enhance bioconversion of lignocellulosic biomass and glycerol to biofuels
title_full Use of process design and metabolic engineering to enhance bioconversion of lignocellulosic biomass and glycerol to biofuels
title_fullStr Use of process design and metabolic engineering to enhance bioconversion of lignocellulosic biomass and glycerol to biofuels
title_full_unstemmed Use of process design and metabolic engineering to enhance bioconversion of lignocellulosic biomass and glycerol to biofuels
title_sort use of process design and metabolic engineering to enhance bioconversion of lignocellulosic biomass and glycerol to biofuels
publisher The Ohio State University / OhioLINK
publishDate 2016
url http://rave.ohiolink.edu/etdc/view?acc_num=osu1480590331055825
work_keys_str_mv AT aguchidozievictoragu useofprocessdesignandmetabolicengineeringtoenhancebioconversionoflignocellulosicbiomassandglyceroltobiofuels
_version_ 1719440845684342784
spelling ndltd-OhioLink-oai-etd.ohiolink.edu-osu14805903310558252021-08-03T06:38:43Z Use of process design and metabolic engineering to enhance bioconversion of lignocellulosic biomass and glycerol to biofuels Agu, Chidozie Victor, Agu Agriculture Animal Sciences Biology Biochemistry Microbiology Molecular Biology Recent efforts to reduce dependency on food-based substrates for industrial applications aim towards the use of inexpensive and readily available non-food based substrates such as lignocellulosic biomass (LB) and biodiesel-derived glycerol. Interestingly, the utilization of lignocellulosic sugars for biofuel production is contingent on the disruption of recalcitrant LB cell wall structure prior to enzyme hydrolysis. Disruption and hydrolysis processes generate lignocellulose-derived microbial inhibitory compounds (LDMIC) including acids, aldehydes and phenolics. Additionally, fermentation of glycerol to butanol, a next-generation biofuel, is hampered by the inability of Clostridium beijerinckii NCIMB 8052, a butanol fermentation workhorse, to efficiently metabolize glycerol. Therefore, this study investigated novel strategies for enhancing butanol and ethanol production through process design and metabolic engineering. Towards process design, the bacterium Cupriavidus basilensis ATCC®BAA-699 was used to detoxify 98% of the LDMIC present in acid-pretreated Miscanthus giganteus (MG) lignocellulosic biomass hydrolysates. Fermentation of the detoxified MG hydrolysates by C. beijerinckii resulted in 70%, 50%, and 73% improvement in acetone-butanol-ethanol (ABE) concentration, yield and productivity, respectively, when compared to the fermentation of undetoxified MG hydrolysates. The second objective was to explore metabolic engineering strategies to enhance glycerol utilization by C. beijerinckii and improve butanol production in the presence of LDMIC. To realize this objective, genes that encode glycerol dehydrogenases (Gldh) and dihydroxyacetone kinase (Dhak) in a hyper-glycerol utilizing bacterium (Clostridium pasteurianum ATCC 6013) were systematically cloned into C. beijerinckii. By over-expressing two C. pasteurianum Gldh genes (dhaD1+gldA1) as a fusion protein in C. beijerinckii, we achieved 50% increase in cell growth, ABE production (up to 40%), and enhanced rate of furfural detoxification (up to 68%) during the fermentation of furfural-challenged (4 to 6 g/L) glucose+glycerol medium. Further, co-expression of dhaD1+gldA1 resulted in significant payoff in cell growth (57%), glycerol consumption (14%), and ABE productivity (27.3%) compared to over-expression of a single Gldh. In parallel, while co-expression of dhak and gldA1 in C. beijerinckii improved glycerol consumption by 37% relative to the plasmid control, over-expression of all three genes (dhaD1+gldA1+dhak) improved butanol production by >50% in the presence of 5 and 6 g/L furfural relative to the plasmid control. Objective 3 aimed to develop a high-throughput alcohol dehydrogenase (ADH)-dependent assay for screening hyper- or hypo- butanol producing C. beijerinckii mutant libraries. Screening of the activities of ADHs from different microorganisms showed that Thermotoga hypogea derived ADH has ~7-fold activity towards butanol than ethanol. It was rationalized that T. hypogea ADH can be used to selectively quantify butanol in the presence ofethanol (e.g., in ABE broth). Objective 4 aimed to use allopurinol to inhibit xanthine dehydrogenase/oxidase and improve ethanol fermentation of LB hydrolysates by Saccharomyces cerevisiae. Allopurinol increased S. cerevisiae growth (19%), ethanol titer (21%), ethanol productivity (20%), ethanol yield (24%), and the chronological lifespan of S. cerevisiae (>16 h) during the fermentation of 100% corn stover hydrolysate. Taken together, this study encompasses novel strategies to enhance LB and glycerol utilization and potentially improve the economics of biobutanol and bioethanol production. 2016 English text The Ohio State University / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=osu1480590331055825 http://rave.ohiolink.edu/etdc/view?acc_num=osu1480590331055825 unrestricted This thesis or dissertation is protected by copyright: some rights reserved. It is licensed for use under a Creative Commons license. Specific terms and permissions are available from this document's record in the OhioLINK ETD Center.

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