bioethanol production

Mohamed Mosaad Abo El-Gheit

MSc. Student, Applied Microbiology, SCU,

Ismailia, Egypt

mhmd.aboelgheit@gmail.com

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

Biofuel: Energy from newly-growing plant

sources

CO2-neutral

alternative source of energy to the current traditional sources e.g. gasoline

CO2 –Neutral?

1st Generation of Bioethanol

Sugars extract ferment

ethanol

sugarcane BRAZIL

(sucrose)

Sugars Hydrolyze (enzymes)

ferment ethanol

USA

(starch)

Cosgrove; 2005

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

2nd Generation of Bioethanol

Cosgrove; 2006

Lignocellulosic Biomass Agricultural Residues:

Source: Quantitative appraisal of biomass resource and their energy potential in Egypt; 2013

Lignocellulosic Biomass: Energy crops: plants which grow at low cost, to make

biofuel.

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

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

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!

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

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

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

Enzyme system

Cellulose Oligosaccharides (<10) Endogluconase

Cellobiose + glucose

glucose

Exoglucanase

Beta-glucosidase

Microbial cellulose utilization fundamental and biotechnology; 2002

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

Actinomycetes and cellulytic activities

Growth Temp Speices

mesophilic M. chalcea

mesophilic S. roseflavus

Mesophilic S. reticuli

Thermophilic Thermobifidia fusca

mesophilic Kibdelosporanguim Philippinenses

Most of actinomycete species can be isolated from both soil and water.

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

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

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???)

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

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

Models of microbial interactions in a consortuim (dual culture)

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

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

Substrate transformation M1 acts on substrate converting

it to a form that can be utilized by M2

e.g. pretreatment of lignocellulosic material

mutualsim

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