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Engineering

Sweet Partnership

The USP Polytechnic School will test a Japanese process for producing biodegradable plastic from bacteria and sugar cane juice

Ana Paula Campos Image EYE OF SCIENCE/SCIENCE PHOTO LIBRARYThe action of a microorganism discovered on the other side of the world may lead to a biodegradable plastic produced from sugarcane. Researchers at the University of the Ryukyus in Okinawa, Japan, found a variety of Bacillus coagulans bacteria in sugarcane molasses that can ferment sugar at a high temperature, up to 54ºC. In sugar cane juice fermentation employed to produce ethanol, which uses Saccharomyces cerevisiae yeast, temperatures reach 34°C. If you surpass this, the microorganism dies. The environment supported by B. coagulans prevents other microorganisms from being present, and this reduces costs related to preventing process contamination. Now, a partnership between the Japanese researchers, the University of São Paulo (USP) and the company Biopol, headquartered in Santana de Parnaíba, in the São Paulo metropolitan region, is trying to make production of the polymer feasible, initially on a pilot scale.

The leader of the Brazilian group, Cláudio Oller, professor in the Chemical Engineering Department at the Polytechnic School (Poli-USP), explains that the process must be performed in a closed, sterile container if the temperature is below 30°C in order to avoid contamination, but this is more difficult and expensive.  “Therein lies the great advantage of the bacterium discovered by Professor Shinichi Shibata,” said Oller. “As it works under high temperatures, it does not suffer competition from other microorganisms. Therefore, fermentation occurs in an open, cheaper environment.”

The group at the University of Ryukyus discovered B. coagulans five years ago and has conducted a series of experiments since then that led to the development of a biodegradable plastic from granulated sugar. In 2008, Shibata and the Brazilian Tunehiro Uono founded the company Biopol Polímeros Vegetais, in the hope of transforming academic research into a marketable product. Shibata has already been to Brazil seven times. The two met indirectly, through television. “My brother was living in Tokyo and saw a report on the news describing research being done in Japan on green plastic made using sugar. He concluded that Okinawa was the likely location of the research, as it is a subtropical region where sugar cane is cultivated. And my daughter lives there. She has a degree in chemistry from USP, and I asked her to investigate in academic circles. That’s how we found Professor Shibata,” says Uono.

The final product is a kind of lactic acid polymer called Poly-L-lactic acid (PLLA), similar to those made from petroleum, but biodegradable. “It’s a kind of polyester,” says Reinaldo Giudici, a colleague in Oller’s department at the Polytechnic School who is also participating in the project. “It can be used to produce packaging films, computer parts, utensils, yarns and fibers for fabrics, or even biodegradable and biocompatible materials for medical applications, for instance.” Early this year, Biopol, through Uono, contacted the Polytechnic School to propose developing the technology in Brazil. The product development partnership between the university and the company was brokered by the Foundation for Engineering Technological Development (FDTE), affiliated with the Polytechnic School. “We bring the university and the company together,” explains engineer André Gertsenchtein, head of FDTE. “To start the project, we invested about R$200,000, which will be returned to us later on. Now we are going to negotiate with BNDES to obtain the resources needed to develop the product,” says Gertsenchtein. Uono estimates that R$10 million will be needed.

In May 2013, Oller, his department colleague Elen Aquino Perpetuo, FDTE director of operations Edith Ranzini, and Uono traveled to Okinawa to learn more about Professor Shibata’s research findings. After returning to Brazil, the group decided to develop a more comprehensive project. Instead of just using sugar, a costly input, it decided to test plastic production using sugarcane juice too, since it is cheaper. Furthermore, according to Oller, sugarcane juice is a source of carbon and several micronutrients, such as nitrogen and phosphorus, that B. coagulans needs for its metabolism. “When using sugar, we must add these micronutrients, which inflates the cost of the process,” he explains. “The idea is to use sugarcane juice as input during the sugarcane harvest months and sugar in the off season.” The objective is to be able to produce the new plastic in Brazilian sugar and alcohol mills. “The process is very similar,” says Uono.

Higher cost
To increase the economic viability of the project, Oller and his team also want to use sugarcane bagasse. “After removing the remaining sucrose, we mix it with polyethylene to make a composite that can be used to manufacture automotive parts,” he says. “The problem is that this composite has an unpleasant odor and can’t be used to make internal components of cars. Our challenge now is to find a way to eliminate the smell.” They predict that the technology for the biodegradable plastic and the odorless composite will be ready to be transferred to industry within two years. Today, polyethylene made from oil is cheaper than plastics made from plants. “We have not yet performed an analysis of the entire process, using bagasse and cane juice,” says Oller. “However, if we can lower costs to a competitive level, the market for our plastic could be huge.”

In the opinion of Professor Sandro Mancini, of the environmental engineering course at the Universidade Estadual Paulista (Unesp) in Sorocaba, biodegradable plastics still have problems related to cost, as they are more expensive than conventional plastics. “But the polymer with which Professor Oller works may represent a breakthrough, because lowering the cost of the process, coupled with the abundance of sugarcane molasses in Brazil, should facilitate production,” says Mancini. Another expert, Professor Telmo Ojeda of the Federal Institute of Education, Science and Technology (IFRS) in Porto Alegre, Rio Grande do Sul, says that, in general, biodegradable plastics cost from 1.5 to 5 times more than petrochemical plastics. “This situation tends to change with increases in production scale and in production process efficiency. In general, consumers are willing to pay about 10% more for a product that has a lower environmental impact,” says Ojeda.

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