WAJIHA SEERAT
Ph.D. Scholar
Department of Botany
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Contents
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 Introduction
 Biofuel Feedstocks: Potential Contributions of Synthetic
Biology
 Synthetic Biology and Biodiesel Production
 Indirect Synthesis of Biodiesel from Microbial Oils
 Direct Synthesis of Biodiesel Using Cell Factories
 Biosynthesis of Ethanol
 Biosynthesis of Fatty Acid Ethyl Esters (Biodiesel)
 Conclusions and Future Perspectives
Global
Warming

Two
major
Problems
Non
renewable
fuel
resources
Green
house gas
emissions

Environment
damage
Entensive
use of
Fossil fuels
Fluctuations
in prices
Instability
of oil
supplies
INTRODUCTION

 Biofuel is energy made from living matter, usually plants
-- renewable energies, emit less than fossil fuels, and have
received increasing attention in the transition to lowcarbon economy
 Bioethanol, biodiesel are types of biofuels
 Bioethanol is an alcohol produced from corn, sorghum,
potatoes, wheat, sugar cane, even biomass such as
cornstalks and vegetable waste
 Biodiesel is made from plant oils such as soybean oil,
palm oil and rapeseed oil.
INTRODUCTION

 White biotechnology centers on the bioproduction
of fuels and chemicals from renewable sources
 About 90% of the current biofuel market is
represented by biodiesel and bioethanol
 Bioethanol is not seen as an ideal biofuel for the
future
 Low energy density
 Incompatibility with the existing fuel infrastructure
Cont’d…

Biodiesel is preferable to petrodiesel







Environmental friendliness
Renewability
Reduced emissions
Higher combustion
Efficiency
Improved lubricity
Higher levels of safety
Cont’d…

 Chemically, biodiesel ------ mixture of fatty acid alkyl
esters (FAAEs).
 Commonly
used
method
Transesterification process
------
in
vitro


Cont’d…

 Issues related to large-scale commercial viability of
biodiesel production
 High cost
 Limited availability of vegetable oils
 In vitro transesterification reaction presents some
unresolved issues
 need to use large amounts of toxic compounds
(sodium hydroxide, sulfuric acid, or methanol)
 high cost of isolation and immobilization of enzyme
catalysts
APPROACHES

interest in developing
 Increasing
microbial
processes
 for the production of biodiesel from a wide range of
other raw materials
 Technologies that use living cells to synthesize
products
 biodegradable
 require less energy
 create less waste during production
Biofuel Feedstocks: Potential Contributions
of Synthetic Biology

 Lignocellulosic agricultural residues
 edible and nonedible crops ---- for the production of
biofuels
 More than 95% of global biodiesel production now
begins from edible vegetable oils
 account for about 80% of the total production cost
 Use of nonedible vegetable oils is significant for
biodiesel production in developing countries,
 tremendous demand for edible oils as food.

Cont’d…

 Increasing attention to the use of microbial oils as
biodiesel feedstock
 produced by certain oleaginous microorganisms
 Lignocellulosic biomass --- largest known renewable
source of carbohydrates
 Synthetic biodiesel can be produced from this
renewable carbon source
Cont’d…

 Techniques used in conversion of lignocellulose into
biofuels appears simple in theory
 not fully established
 The yield and productivity of biofuels synthesized in
this way are not sufficient to meet current energy
demands.
Cont’d…

 In ethanol production,
 Starches (maize, wheat, barley, etc.)
 Sugar-rich biomass (grasses, maize leaves, beets,
sugar cane, etc.)
 Feedstocks most commonly used for their
bioconversion
 Ethanol is one of the substrates
 used for in vivo synthesis of biodiesel
Synthetic Biology and Biodiesel Production

 Synthesis of biodiesel using microbes --- alternative
to conventional technologies
 Microbial biodiesel production from two different
angles:
 By indirect synthesis from microbial oils
 By direct biodiesel synthesis using redesigned cell
factories
Indirect Synthesis of Biodiesel from Microbial
Oils

 Oils derived from oleaginous microbes
 represent promising raw materials for biodiesel
production
 through transesterification using the plant-based
process
 Microalgae are photoautotrophic microorganisms
that can convert CO2 directly to lipids,
 which can then be used for biofuel production,
particularly for biodiesel

Cont’d…

 Tools from synthetic biology used to convert certain
autotrophic
microalgae
into
heterotrophic
microorganisms
 Introduction of non-natural metabolic pathways into
the autotrophic microalgae
 allowing cultivation using an organic carbon source
instead of photosynthesis from sunlight
Direct Synthesis of Biodiesel Using Cell
Factories

endogenously
 Ethanol produced
--- for in vivo
synthesis of fatty acid ethyl esters (FAEEs) with
exogenously added FFAs.
 Microbial FFAs can be used as feedstock for in vivo
production of biodiesel
Biosynthesis of Ethanol

Biosynthesis of Fatty Acid Ethyl Esters
(Biodiesel)

 Direct synthesis of biodiesel from microbes produces
primarily FAEEs, which show better performance as
a fuel than FAMEs
 An important discovery related to this was a novel
bifunctional
wax
ester
synthase/acyl-CoA:
diacylglycerol acyltransferase (WS/DGAT) isolated
from Acinetobacter baylyi strain ADP1.
 This enzyme can synthesize wax esters from alcohols
and fatty acids

Cont’d…

 An E. coli strain was manipulated
 for improvement of the biosynthesis of FFAs
 for derivatives including fatty esters
CONCLUSION & FUTURE PERSPECTIVES

 Metabolic engineering and synthetic biology allowing
new technologies to be developed
 As evident in the design and refinement of microbial cell
factories amenable to industrial applications
 Biodiesel production through the use of microbial
systems has marked a turning point in the field of
biofuels
 The possibility of developing a synthetic host for efficient
target-molecule production presents great opportunities
for further biofuel research
Cont’d…

 Investment of significant amounts of time and effort
is still required in order to produce a better host
 Carrying novel metabolic pathways to lead to
satisfactory biofuel production
 More engineering of all of the genes needed to
produce the desired pathway is not sufficient to
confer a novel characteristic to a recombinant cell,
since there are always many other unexplored
pathways as well.
REFERENCE

 Veronica L. C., A. Rodriguez and H. A. Cristobal. 2011. The
Role of Synthetic Biology in the Design of Microbial Cell
Factories for Biofuel Production Journal of Biomedicine and
Biotechnology, 0.1155/2011/601834, 1-9.
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