CURRENT RESEARCH INTERESTS
1. Biofuels (ethanol and hydrogen) production from cellulosic biomass
The long term goal of this research is to understand factors involved in modulating carbon and electron flow through fermentative pathways in biofuel (H2 and ethanol) producing anaerobes; first, by identifying the electron transferring enzymes involved, then, by studying the regulation of synthesis and activity of these enzymes under different growth conditions. Much of this research is focused on Clostridium thermocellum and Thermoaanerobacter thermohydrosulfuricum WC1.
C. thermocellum produces H2, CO2, acetate, ethanol and lactate from the fermentation of cellulose. Its effective cellulosome complex makes it useful for the fermentation of cellulosic waste products (paper, wood fiber, straw etc.) to alternative fuels (H2 or ethanol). Its recently sequenced genome permits bioinformatic analysis, and a reevaluation of its fermentation pathways. Early work overlooked formate as a fermentative end product, which we have recently observed, as well as cell extract activities of pyruvate formate lyase (PFL). Putative sequences for these enzymes have been noted. The genome sequence also suggests the presence of a ferredoxin (fd) dependent energy conserving hydrogenase (ECH) seldom seen in clostridia, but observed in most methanogens, along with NAD(P) dependent hydrogenases (HYD). Three apparent copies of pyruvate: fd oxidoreductase (POR) are also observed. From pyruvate, 2 pathways can potentially generate H2, one involving POR and ECH, the other, POR, NADH:fd oxidoreductase and HYD. We expect that the relative expression of these enzymes will be regulated by the choice of substrate, rate of carbon assimilation, pH, and end-product concentrations. In addition, a NADH:fd oxidoreductase may modulate electron flow from glycolysis and pyruvate degradation through NADH vs fd. Much of this work is funded thanks to a collaborative grant from Genome Canada (http://www.microbialrefinery.com/). With the assistance of Oleg Krokhin and John Wlkins and their teams of the Manitoba Systems Biology Centre (http://www.proteome.ca), we are studying the levels of proteins within the proteome associated with various growth conditions to look at the pattern of protein exptression associated with best biofuels production.
A further aspect is to perform some bioprospecting to look for novel cellulolytic and biofuel producing anaerobes for the development of synergistic consortia with enhanced capabilities for both lignocellulose degradation and biofuel production (in collaboration with David Levin, as well as Martina Hausner and Gideon Wolfaardt from Ryerson U., and Josh Neufeld from Waterloo U.) . We also have a further collaboration with Matthew Stott and GNS in New Zealand to look at novel thermophilic organisms from the hot sprongs of the North Island (http://www.gns.cri.nz/who/staff/2150.html). Through the current Genome Canada project, genomic sequencing and proteomic analysis will be pursued in order to understand the interactions between C. thermocellum and other cellulolytic biofuels producers with “helper bacteria” capable of positive interactions in defined consortia.
2. Microbiological issues surrounding digestion of organic municipal and agricultural wastes.
Part of this work focuses on bio-optimization of value added products (biofuels: methane, hydrogen, solvents) from the organic fraction of municipal and agricultural solid and liquid wastes, pathogen removal as well as biological phosphate and nitrogen removal from these wastes (collaborative work with J. Oleszkiewicz, Civil Engineering, and N. Cicek, Biosystems Engineering). My role in these collaborative efforts is to provide microbiological expertise and experimental approaches to understanding the microbial communities involved in carbon, nitrogen and phosphorous cycling in the man-made environments.
RECENT and CURRENT research grants in support of these projects:
Research Operating grants
2009-2013
Genome Canada grant
D. B. Levin and R. Sparling (Co-leaders), T. Charles, B. Firstinsky, K. Ma, S. Smyth, H. Venema, J. Wilkins, G. Wolfaardt,
Microbial genomics for biofuels and co-products from biorefinaries
$2 260 000/year total
2009-2012 NSERC Collaborative Research and Development Grant (CRDPJ), with Earth Tech (Canada) Inc., City of Winnipeg
J.A. Oleszkiewicz, R. Sparling
Optimization of phosphorous removal in municipalities served by regional sludge processing facilities
$43 000/year total
2008-2011 NSERC Strategic Grant
M. Hausner, G. Wolfhaardt, J. Neufeld, R. Sparling, D. Levin
Development of designer microbial consortia for bioconversion of cellulose to energy and value-added products
$146 2000/yr total
2007-2010 Manitoba Rural Adaptation Council
D. Levin, R. Sparling, N. Cicek
Biofuel and value-added co-product
synthesis from wheat dried distillers grain
$ 26 500/yr
2007-2009 NSERC Strategic Grant
D. Levin, R. Sparling
Metabolic engineering for third generation biofuels
$95 000/yr total
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