On April
6, National University of Singapore (NUS) announced
that its team of engineers has recently discovered a greener and cheaper technique
for biofuel production, using a natural bacterium isolated from mushroom crop
residue.
Traditional biofuels are produced from food crops. This
approach is highly costly and competes with food production in the use of land,
water, energy and other environmental resources. Biofuels produced from unprocessed cellulosic materials such
as plant biomass, as well as agriculture, horticultural and organic waste, are
expected to meet growing energy demands without increasing greenhouse gas
emissions resulting from the burning of fossil fuels. These cellulosic
materials are in great abundance, environmentally friendly, and economically
sustainable.
Among various types of biofuels, biobutanol offers a great
promise as petrol substitute because of its high energy density and superior
properties.
Biobutanol can directly replace gasoline in car engines without any
modification. However, commercial production of biobutanol has been hampered by
the lack of potent microbes capable of converting cellulosic biomass into
biofuels. The current technique is costly and also requires complicated
chemical pre-treatment.
The novel technique developed by the NUS team could
potentially be a game-changing technology for cost effective and sustainable
biofuel production.
A
research team led by Associate Professor He Jianzhong from the Department of
Civil and Environmental Engineering at NUS Faculty of Engineering first
discovered the novel TG57 strain in 2015.
The
team discovered that a naturally-occurring bacterium Thermoanaerobacterium
thermosaccharolyticum (TG57) isolated from waste generated after
harvesting mushrooms, is capable of converting cellulose to biobutanol directly.
The team then went on to culture the strain to examine its properties.
Spent mushroom compost – typically composed of wheat straw
and saw dust – is the residual compost waste generated by mushroom farming. The
microorganisms in the waste are left to evolve naturally for more than two
years to obtain the unique TG57 strain.
The fermentation process is simple, and no complicated
pre-treatment or genetic modification of the microorganisms is required. When
cellulose is added, the bacterium simply digests it to produce butanol as the
main product.
Associate
Professor He explained that the production of biofuels using non-food
feedstocks can improve sustainability and reduce costs greatly.
“In
our study, we demonstrated a novel method of directly converting cellulose to
biobutanol using the novel TG57 strain. This is a major breakthrough in
metabolic engineering and exhibits a foundational milestone in sustainable and
cost-effective production of renewable biofuels and chemicals,” said Associate
Professor He.
Moving forward, the research team will continue to optimise
the performance of the TG57 strain, and further engineer it to enhance
biobutanol ratio and yield using molecular genetic tools.
The team published the findings of the study in the
scientific journal Science Advances on 23 March 2018.
