Pectin-rich biomass as feedstock for fuel ethanol production

The USA has proposed that 30 % of liquid transportation fuel be produced from renewable resources by 2030 (Perlack and Stokes 2011). It will be impossible to reach this goal using corn kernel-based ethanol alone. Pectin-rich biomass, an under-utilized waste product of the sugar and juice industry, can augment US ethanol supplies by capitalizing on this already established feedstock. Currently, pectin-rich biomass is sold (at low value) as animal feed. This review focuses on the three most studied types of pectin-rich biomass: sugar beet pulp, citrus waste and apple pomace. Fermentations of these materials have been conducted with a variety of ethanologens, including yeasts and bacteria. Escherichia coli can ferment a wide range of sugars including galacturonic acid, the primary component of pectin. However, the mixed acid metabolism of E. coli can produce unwanted side products. Saccharomyces cerevisiae cannot naturally ferment galacturonic acid nor pentose sugars but has a homoethanol pathway. Erwinia chrysanthemi is capable of degrading many of the cell wall components of pectin-rich materials, including pectin. Klebsiella oxytoca can metabolize a diverse array of sugars including cellobiose, one degradation product of cellulose. However, both E. chrysanthemi and K. oxytoca produce side products during fermentation, similar to E. coli. Using pectin-rich residues from industrial processes is beneficial because the material is already collected and partially pretreated to facilitate enzymatic deconstruction of the plant cell walls. Using biomass already produced for other purposes is an attractive practice because fewer greenhouse gases (GHG) will be anticipated from land-use changes

Biorefinery and Hydrogen Fuel Cell Research

In this project we focused on several aspects of technology development that advances the formation of an integrated biorefinery. These focus areas include: [1] establishment of pyrolysis processing systems and characterization of the product oils for fuel applications, including engine testing of a preferred product and its pro forma economic analysis; [2] extraction of sugars through a novel hotwater extaction process, and the development of levoglucosan (a pyrolysis BioOil intermediate); [3] identification and testing of the use of biochar, the coproduct from pyrolysis, for soil applications; [4] developments in methods of atomic layer epitaxy (for efficient development of coatings as in fuel cells); [5] advancement in fermentation of lignocellulosics, [6] development of algal biomass as a potential substrate for the biorefinery, and [7] development of catalysts from coproducts. These advancements are intended to provide a diverse set of product choices within the biorefinery, thus improving the cost effectiveness of the system. Technical effectiveness was demonstrated in the pyrolysis biooil based diesel fuel supplement, sugar extraction from lignocelluose, use of biochar, production of algal biomass in wastewaters, and the development of catalysts. Economic feasibility of algal biomass production systems seems attractive, relative to the other options. However, further optimization in all paths, and testing/demonstration at larger scales are required to fully understand the economic viabilities. The various coproducts provide a clear picture that multiple streams of value can be generated within an integrated biorefinery, and these include fuels and products

Characterization of Two Paenibacillus amylolyticus Strain 27C64 Pectate Lyases with Activity on Highly Methylated Pectin ▿ †

Two pectate lyases were identified from Paenibacillus amylolyticus 27C64; both enzymes demonstrated activity on methylated pectin in addition to polygalacturonic acid. PelA is in a subclass of the pectate lyase family III. PelB shows some features of pectate lyase family I but is highly divergent

Isolation of Polymer-Degrading Bacteria and Characterization of the Hindgut Bacterial Community from the Detritus-Feeding Larvae of Tipula abdominalis (Diptera: Tipulidae)▿

The Tipula abdominalis larval hindgut microbial community presumably facilitates digestion of the lignocellulosic diet. The microbial community was investigated through characterization of bacterial isolates and analysis of 16S rRNA gene clone libraries. This initial study revealed novel bacteria and provides a framework for future studies of this symbiosis

MOESM2 of Phenotypic characterization and comparative transcriptomics of evolved Saccharomyces cerevisiae strains with improved tolerance to lignocellulosic derived inhibitors

Additional file 2: Table S2. Primer sequences used for Comparative CT RT-PCR

Addition of Genes for Cellobiase and Pectinolytic Activity in Escherichia coli for Fuel Ethanol Production from Pectin-Rich Lignocellulosic Biomass▿

Ethanologenic Escherichia coli strain KO11 was sequentially engineered to contain the Klebsiella oxytoca cellobiose phosphotransferase genes (casAB) as well as a pectate lyase (pelE) from Erwinia chrysanthemi, yielding strains LY40A (casAB) and JP07 (casAB pelE), respectively. To obtain an effective secretion of PelE, the Sec-dependent pathway out genes from E. chrysanthemi were provided on a cosmid to strain JP07 to construct strain JP07C. Finally, oligogalacturonide lyase (ogl) from E. chrysanthemi was added to produce strain JP08C. E. coli strains LY40A, JP07, JP07C, and JP08C possessed significant cellobiase activity in cell lysates, while only strains JP07C and JP08C demonstrated extracellular pectate lyase activity. Fermentations conducted by using a mixture of pure sugars representative of the composition of sugar beet pulp (SBP) showed that strains LY40A, JP07, JP07C, and JP08C were able to ferment cellobiose, resulting in increased ethanol production from 15 to 45% in comparison to that of KO11. Fermentations with SBP at very low fungal enzyme loads during saccharification revealed significantly higher levels of ethanol production for LY40A, JP07C, and JP08C than for KO11. JP07C ethanol yields were not considerably higher than those of LY40A; however, oligogalacturonide polymerization studies showed an increased breakdown of biomass to small-chain (degree of polymerization, ≤6) oligogalacturonides. JP08C achieved a further breakdown of polygalacturonate to monomeric sugars, resulting in a 164% increase in ethanol yields compared to those of KO11. The addition of commercial pectin methylesterase (PME) further increased JP08C ethanol production compared to that of LY40A by demethylating the pectin for enzymatic attack by pectin-degrading enzymes

Biorefinery and Hydrogen Fuel Cell Research

In this project we focused on several aspects of technology development that advances the formation of an integrated biorefinery. These focus areas include: [1] establishment of pyrolysis processing systems and characterization of the product oils for fuel applications, including engine testing of a preferred product and its pro forma economic analysis; [2] extraction of sugars through a novel hotwater extaction process, and the development of levoglucosan (a pyrolysis BioOil intermediate); [3] identification and testing of the use of biochar, the coproduct from pyrolysis, for soil applications; [4] developments in methods of atomic layer epitaxy (for efficient development of coatings as in fuel cells); [5] advancement in fermentation of lignocellulosics, [6] development of algal biomass as a potential substrate for the biorefinery, and [7] development of catalysts from coproducts. These advancements are intended to provide a diverse set of product choices within the biorefinery, thus improving the cost effectiveness of the system. Technical effectiveness was demonstrated in the pyrolysis biooil based diesel fuel supplement, sugar extraction from lignocelluose, use of biochar, production of algal biomass in wastewaters, and the development of catalysts. Economic feasibility of algal biomass production systems seems attractive, relative to the other options. However, further optimization in all paths, and testing/demonstration at larger scales are required to fully understand the economic viabilities. The various coproducts provide a clear picture that multiple streams of value can be generated within an integrated biorefinery, and these include fuels and products