Fermentation of renewable agricultural or waste materials to convert them into fuel or other valuable products
One of the specific microbial activities targeted in the BEEM project is the conversion of recalcitrant biomass into bioenergy and biochemicals, turning plant-fibres and mill waste streams such as bark into high-value materials.
The BEEM project uses samples collected from sites that have had a long historical exposure to these types of biomass, so that the desired activity may already have evolved within the native microbial community. These include wood mill heritage piles, landfills, and anaerobic digestors. We also recognize that some of Canada's most characteristic (and beloved) animals, the moose and beaver, feed on wood and have likely evolved unique microbial flora in their digestive systems that can efficiently degrade wood's highly recalcitrant components. Moose rumen and beaver droppings are included in the environmental samples that form the basis for laboratory studies.
Samples from these environmental sites have and will be used to construct microcosms in the lab in which the biotransformation of natural substrates such as bark by native organisms will be monitored using standard wet chemistry and chromatography. Microcosms showing the desired activity will be manipulated to encourage growth of relevant microbial species. This process, known as enrichment, includes transferring aliquots of the culture to sterile synthetic medium and amending them with compounds of interest to stimulate growth. After enrichment, metabolite analysis will be carried out to screen for valuable enzymes. Functional analysis of the resulting enriched cultures will identify the microorganisms and enzymes involved in the biotransformations. Some of the potential commercial products from these are biopolymers and 1,4-diacids froms waste, bioenergy, diols and glyceral esters from waste glycerol, and inhibitor-resistant fermentative strains for consolidated bioprocesses (CBP).
Anaerobic microbial processes -- those that do not require the presence of oxygen -- are of particular interest for the microbial conversion of biomass for several reasons. First, anaerobic environments are quite common in nature and anaerobes play key roles in all biogeochemical cycles. They are thus abundant and diverse -- a large pool of potentially useful organisms with a wide range of capabilities. Second, anaerobic microorganisms tend to produce valuable compounds during fermentation, such as butanol and methane (biogas that can be used as fuel). In fact, anaerobic respiration and fermentation are fundamental to the commercial production of biochemicals, biopolymers and bioenergy. In addition, anaerobes used in industrial applications do not need expensive aeration, they produce less biomass or sludge in digestors, and anaerobic cellulose biodegradation is a pre-requisite for CBP for biofuel production.
Despite their critical role in the future bioeconomy, examples of the systematic characterization and application of anaerobic microorganisms are gravely lacking. Working with anaerobes requires specialized equipment and their slow growth rates may require long experiments. BEEM researchers are one of the few teams in Canada with demonstrated expertise in the enrichment and characterization of anaerobic cultures and their commercial applications, both in the remediation and pulp and paper industries.
New industrial partners are welcomed -- please contact info.beem@utoronto.ca.
