Bioethanol Production


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Production of Ethanol from Cellulose Residues: Microbiological Approaches

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Bioethanol Production

  1. 1. Mohamed Mosaad Abo El-Gheit MSc. Student, Applied Microbiology, SCU, Ismailia, Egypt
  2. 2. Contents:  Biofuel  Types of Biofuel  1st and 2nd generation of Bioethanol  Lignocellulosic Biomass in Egypt  Composition of Lignocellulose  Pretreatment of Lignocellulose  Microbial Enzymatic Hydrolysis  Bioprocessing of Biomass  Cellulosic Activities in Actinomycetes  Microbial Consortia
  3. 3. Biofuel: Energy from newly-growing plant sources CO2-neutral alternative source of energy to the current traditional sources e.g. gasoline
  4. 4. CO2 –Neutral?
  5. 5. 1st Generation of Bioethanol Sugars extract ferment ethanol sugarcane BRAZIL (sucrose) Sugars Hydrolyze (enzymes) ferment ethanol USA (starch) Cosgrove; 2005
  6. 6. Types of Biofuel  Solid  animal wastes and agricultural residues can be used as sources of energy by direct burning (primitive way)  Liquid  Bioethanol C2H5OH ( fermentation of sugar)  Biodiesel (by saturation of vegetable oils)  Gas  e.g. methane and biogas derived from organic wastes by anaerobic digestion Organic wastes Heat energy Direct burning
  7. 7. 2nd Generation of Bioethanol Cosgrove; 2006
  8. 8. Lignocellulosic Biomass  Agricultural Residues: Source: Quantitative appraisal of biomass resource and their energy potential in Egypt; 2013
  9. 9. Lignocellulosic Biomass:  Energy crops: plants which grow at low cost, to make biofuel. 
  10. 10. Composition of Lignocellulose  Cellulose  Hemicelluloses  Lignin Ash Extractives Cellulose Hemicellulose (both 5 and 6 carbon sugars) (need modified microbe to convert to ethanol) Ash Extractives Lignin (phenols) (6 carbon sugars) Chapple, 2006; Ladisch, 1979, 2006
  11. 11. Pretreatment  break down the shield formed by lignin and hemicellulose  Open the fiber structure  reduce the degree of polymerization of cellulose. Source: Overview of biomass pretreatment for cellulosic ethanol production; 2009
  12. 12.  Pretreatment has been viewed as one of the most expensive processing steps within the conversion of biomass to fermentable sugar  Pretreatment methods maybe: physical, chemical or biological  Biological:  Adv. : no chemicals, no energy requirements, mild environmental conditions  Disadv.: slow, the activity of the microorganisms maybe not specific to lignin only!
  13. 13. Pretreated Lignocellulose  What is “Pretreated Biomass”? increased surface area, solubilization of cellulose, redistribution of cellulose and lignin  Cellulose 35-50%  Hemicellulose 20- 35%  Lignin 5-30% Microbial cellulose utilization fundamental and biotechnology; 2002
  14. 14. Enzymatic Treatment Pretreated Lignocellulose Pentoses and hexoses + lignin and lignin degradation Enzymatic Hydrolysis cellulose glucose hemicellulose glucose + xylose+ other C5 and C6 sugars Microbial cellulose utilization fundamental and biotechnology; 2002
  15. 15. Microbial Enzyme system:  Substrate  cellulose + hemicellulose  Enzymes:  endoglucanases: cut at random internal sites along the cellulose/hemicellulose chain  exoglucanases: act at reducing and nonreducing ends  beta-glucosidase: break betaglucoside bond to form glucose
  16. 16. Enzyme system Cellulose Oligosaccharides (<10) Endogluconase Cellobiose + glucose glucose Exoglucanase Beta-glucosidase Microbial cellulose utilization fundamental and biotechnology; 2002
  17. 17. Lignocellulosic Activities of Actinomycetes  According to Lynd et al (2002) there is a considerable concentration of cellulytic capabilities among Actinomyceltales.  Actinomycetes are well known for their ability to decompose complex molecules, particularly lignocellulose components  Micromonospora spp and Strptomyces spp are well known for their decomposition ability on Biomass
  18. 18. Actinomycetes and cellulytic activities Growth TempSpeices mesophilicM. chalcea mesophilicS. roseflavus MesophilicS. reticuli ThermophilicThermobifidia fusca mesophilicKibdelosporanguim Philippinenses Most of actinomycete species can be isolated from both soil and water.
  19. 19. Bioprocessing of cellulosic Biomass  Steps (mediated events): 1) Cellulase production 2) Hydrolysis of cellulose/hemicellulose 3) Fermentation of cellulose hydrolysis products e.g. glucose 4) Fermentation of hemicellulose hydrolysis products other than glucose e.g. xylose biomass fuel Microbial cellulose utilization fundamental and biotechnology; 2002
  20. 20. Bioprocessing of cellulosic Biomass This diagram shows the capability of consolidation or separation of mediate events (steps) of bioprocessing of Biomass Source: Microbial cellulose utilization fundamental and biotechnology; 2002 • SHF: Separated Hydrolysis and Fermentation • SSF: Simultaneous Saccharification and Fermentation • SSCF: Simultaneous Saccharification and Cofementation • CBP: Consolidate Bioprocessing
  21. 21. Consolidated Bioprocessing CBP  In which all bioprocessing steps are combined together as one process  Biomass processing technology has exhibited a trend toward increasing consolidation over time  Advantages  Efficiency + Economically effective  CBP organisms:  Single organism  Community of organisms( symbiotic consortium) (which is more efficient???)
  22. 22. Symbiotic Consortium  A community of organisms  i.e 2 or more organisms living in association  Symbiosis may be : mutualism, commensalism, o antagonism  Types:  Natural consortuim  Engineered consortuim Genetically Recombined natural capabilities i.e. ecological approaches
  23. 23. Natural Consortium  The main problem  doesn’t accumulate high levels of biofuel why?  Biofuel molecules are molecules of energy  Biofuels represents an a pportunity for a new consortia member (organism) to exploit  Natural consortia tend to thermodynamically free energy of molecules till the lowest level  Be overcome by  engineering consortia
  24. 24. Models of microbial interactions in a consortuim (dual culture)
  25. 25. Sequential utilization  2 oranisms M1 and M2  The fuel molecule (F1) is considered a waste product of M1. However, it is degraded by M2 as source of energy e.g. commensalism  No accumlation of fuel molecules
  26. 26. Co-utilization  M1 & M2 are competing to utilize the substrate , producing fuel molecules  Competitive symbiosis i.e. controlled by inhibitors /activatiors  Fuel considered waste product of both organsims  There is accumulation of fuel
  27. 27. Substrate transformation  M1 acts on substrate converting it to a form that can be utilized by M2  e.g. pretreatment of lignocellulosic material  mutualsim
  28. 28. Product transformation  M1 produces fuel products as waste product  M2 act on fuel to convert it into an alternative fuel  Look like sequential utilization. However, the fuel molecules are converted to alternative fuel , not completely utilized