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By Ira Karen Apanay, Senior Reporter
Three students from Ateneo de Manila University
have found a way to make bioethanol from rice straws, a development
that can potentially reduce the country’s dependence on imported
fossil fuels.
The students—Miguel Angelo Vicente, Dulce
Marie Romea and Jose Maria Villamor—conducted a study where they
found out that a mixture of microorganisms can produce bioethanol
from rice straws through a process called cellulose degradation.
The three students said the rice straws, which
are traditionally treated as waste and are simply burned or fed to
animals, can be collected and exploited as feedstock that can
produce 205 billion liters of bioethanol per year.
The study could provide the solution to the
problem of limited agricultural lands being used, not for food
production, but for plants that produce biofuels, like ethanol, the
students said.
“It’s a source that does not directly
influence the price of the rice itself as a food source,” the
students added.
With the production of bioethanol from rice
straws, the students said the Philippines has a good chance of
competing with Brazil, which produces biofuel from sugarcane, and
the United States, which has committed itself to produce 20 percent
of its energy needs from biofuels, made principally from corn.
Professor Crisanto Lopez, the students’ thesis
adviser, said the production of biofuel from rice straws is an ideal
solution to the problem, since the expansion of rice-producing areas
means not only higher palay (unhusked rice) yield but also an
increase in generation of rice straws.
“We might lose land for food, [but] instead it
will be used for production of fuels,” he said. “We don’t want
that to happen. We are an agricultural country, and we want food for
our people.”
“Through the use of a substrate, like rice
straws which is just a byproduct of palay production, it can help in
the production of bioethanol, which is an alternative source of
fuel,” Lopez said.
For cellulose degradation to be highly
effective, Lopez explained, “it’s either you look for the most
active and most effective enzymes or you just use the microorganisms
which are newly isolated or you genetically engineer microorganisms
so that they can produce the enzymes.”
The students used three different organisms in
the experiment. This was done by using Phanaerochete chrysosporium
as an alternative to sulfuric acid as the primary lignin degrader,
Trichoderma reesei as the source of cellulase, and Saccharomyces
cerevisiae as the fermenting microorganism.
“They are all fungi,” the students
explained. “They are different from bacteria. Fungi are eukaryotes,
while bacteria are prokaryotes. Trichoderma reesei is used to
produce the enzyme cellulase. In the industry, they just let the
fungus produce the enzyme and then purify it. The Phanaerochete
chrysosporium is a white rot fungus usually seen in old wood, while
the Saccharomyces cerevisiae is a yeast normally used for the
fermentation of beer and other alcoholic beverages.”
In the study, the students used three different
experimental set-ups. First, they tested the synergistic
capabilities of the three organisms. Second, the group tried to
figure out if the organisms worked more efficiently when they were
introduced to the rice straws one at a time. The third set-up used
in the study was to determine whether the presence of Phanaerochete
chrysosporium was a prerequisite for the effective production of
bioethanol, because of its capability to produce ligninase.
Lopez said the students had to evaluate each
result based on a control set-up that is used to produce bioethanol
from corn and sugarcane.
“The results were compared to the results of a
control set-up which simulated the procedure done in industrial
ethanol production processes,” according to the students.
After the tests were done, the students
concluded that the best set-up was when they combined the three
organisms.
“What they just investigated is, if they could
actually put the three microorganisms at the same time or one at a
time, similar to sequential addition,” Lopez said. “They found
out that if you place the three microorganisms at the start then it
will produce more bioethanol after fermentation. Several
combinations showed that addition of the three microorganisms at the
start of the fermentation will produce more or higher bioethanol.”
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