Anaerobic fermentation of glycerol: a path to economic viability for the biofuels industry Syed Shams Yazdani and Ramon Gonzalez

Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street, MS-362, Houston, TX 77005, USA.
Current Opinion in Biotechnology (Impact Factor: 7.12). 07/2007; 18(3):213-9. DOI: 10.1016/j.copbio.2007.05.002
Source: PubMed


Although biofuels such as biodiesel and bioethanol represent a secure, renewable and environmentally safe alternative to fossil fuels, their economic viability is a major concern. The implementation of biorefineries that co-produce higher value products along with biofuels has been proposed as a solution to this problem. The biorefinery model would be especially advantageous if the conversion of byproducts or waste streams generated during biofuel production were considered. Glycerol-rich streams generated in large amounts by the biofuels industry, especially during the production of biodiesel, present an excellent opportunity to establish biorefineries. Once considered a valuable 'co-product', crude glycerol is rapidly becoming a 'waste product' with a disposal cost attributed to it. Given the highly reduced nature of carbon in glycerol and the cost advantage of anaerobic processes, fermentative metabolism of glycerol is of special interest. This review covers the anaerobic fermentation of glycerol in microbes and the harnessing of this metabolic process to convert abundant and low-priced glycerol streams into higher value products, thus creating a path to viability for the biofuels industry. Special attention is given to products whose synthesis from glycerol would be advantageous when compared with their production from common sugars.

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Available from: Syed Shams Yazdani, Oct 09, 2015
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    • "720 g l À1 of glycerol in water) can occur (Clomburg and Gonzalez 2013). It may be assumed therefore, that conversion of this low-or even negative-value product to higher added-value compounds by the means of chemical or fermentation technology currently attracts high and continuously increasing interest; as far as biotechnological conversions are concerned, in several cases, prokaryotic micro-organisms have been implicated in the fermentative conversion of (crude) glycerol into compounds such as bioalcohols (principally 1,3-propanediol and to a lesser extent 2,3-butanediol, ethanol and butanol), poly-(hydroxylakanoates ), biosurfactants, dihydroxyacetone and succinic acid (Yazdani and Gonzalez 2007; Celi nska and Grajek 2009; Clomburg and Gonzalez 2013; Kachrimanidou et al. 2013). Likewise, a significant number of reports, appearing in most cases in the past few years, indicates the potential of eukaryotic micro-organisms (yeasts, molds and heterotrophically grown algae) to convert (crude) glycerol into a plethora of metabolic compounds of added-value, such as microbial lipids (also called single cell oils, SCOs) citric acid, microbial mass, enzymes and polyols (for reviews see: Papanikolaou and Aggelis 2009; Rivaldi et al. 2009; Wen et al. 2009a,b; Rywi nska et al. 2013a; Abghari and Chen 2014). "
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