Scientists aim to link the ethanol production chain to the manufacture of bioplastics
August 22, 2012
By Fábio de Castro
Agência FAPESP – With the significant production of ethanol in Brazil, it has become increasingly important to develop new alternatives for the utilization of sugarcane byproducts and residue. One proposed strategy consists of linking the ethanol production chain to the manufacture of polyhydroxyalkanoate (PHA), a biodegradable plastic that is produced by bacteria from sugarcane bagasse.
This was one of the themes discussed on the “Sustainable Production of Biopolymers and Other Biobased Products” workshop held at FAPESP’s headquarters on July 25-26. The objective of this two-day event was to bring together the academic and business communities to discuss the development of biobased products in the context of society’s use of nonrenewable sources.
The workshop was part of the FAPESP Bioenergy Research Program (BIOEN) and received support from the Ibero-American Program for Science and Technology Development (CYTED), an intergovernmental cooperation initiative among 19 countries in Latin America, Spain and Portugal and the Universidade de São Paulo’s Biomedical Sciences Institute (ICB-USP).
According to the event organizer, Luiziana Ferreira da Silva, a professor at ICB-USP, Brazil has been engaged in PHA research for 20 years, yielding good results and a series of patents. Technologies developed by ICB-USP, the Institute of Technological Research (IPT) and the former Cooperative of Sugarcane, Sugar and Ethanol Producers (Copersucar) have been transferred to a company in São Paulo.
According to Silva, certain bacteria synthesize PHA from organic material. Once extracted by bacteria, it generates a polymer that can be molded into shapes, like any petrochemical-based plastic but with the advantage of biodegradability.
“This allows us to obtain material with plastic or elastomeric properties using bacteria and renewable material, such as sugarcane, soybean or other plant residue. Because it is a biodegradable plastic made from renewable raw materials, the product has a good environmental profile from production to application,” Silva stated in an interview with Agência FAPESP.
In addition to being biodegradable, PHA bioplastics are also biocompatible, which means that they can be used to manufacture implants for use in people and animals that raise fewer concerns about immune rejection than currently used materials. “It is an interesting alternative to petrochemical-based plastics. To have an idea of the array of applications, just look around you and count how many plastic objects there are,” said Silva.
PHA can be utilized to manufacture biodegradable plastic films, for example. “Sanitary napkins and diapers are coated with plastic films. The disposal of these materials is a serious environmental problem. A biodegradable polymer that can substitute for the films used in these products would contribute greatly to preserving the quality of the environment,” explained Silva.
Other potential applications of PHA are the manufacture of biocompatible microcapsules containing medicine or hormones and the production of implants to allow controlled release of drugs. “PHA can be used to make orthopedic pins that are degraded by the body and do not need to be removed after recovery from the injury,” she noted.
Although BIOEN has focused on biofuels, the studies of PHA and other biopolymers and biobased products are part of the research program targeting “Biorefineries and Alcohol-chemistry.”
“Sugarcane bagasse can be used to produce energy based on fuels or to produce so-called cellulosic ethanol. But this ethanol is not produced through the same fermentation process that produces the first-generation ethanol,” said Silva.
The bagasse is “broken down” into a mix of sugars. However, the fermentation that uses glucose to make ethanol does not use xylose. Thus, even if the bagasse is broken down and subjected to a fermentation reaction to produce ethanol, the xylose in the sugar mixture will not be used.
“Under BIOEN, several researchers are studying how to make the fermentation process that produces ethanol utilize xylose as well as glucose, to take full advantage of the bagasse. Nevertheless, other biobased products can be produced using xylose,” said Silva.
With PHA production, scientists hope to offer an alternative use for bagasse. “If no one can determine how to make the fermentation reaction utilize xylose to make ethanol, we will have an alternative use for the material — making bioplastics. Our idea is to create biorefineries, which would be ethanol mills linked to small companies that produce bioplastics or another product that uses xylose,” she said.
Interaction with companies
According to the ICB-USP professor, more basic research is needed to reach this stage, for example, to modify bacteria in such a way that they can produce different types of bioplastics. Furthermore, beyond the strictly scientific point of view, to achieve a sustainable process, the researchers must recruit the help of professionals from other areas and deepen their interactions with industrial sector.
“One of the bottlenecks consists of controlling the composition of the bioplastics. But we cannot simply work at the laboratory bench without involving the manufacturing sector. That is why we brought companies to the workshop. To make these processes applicable on a large scale, we have to interact with them and raise issues like questions of biosafety, the properties of plastic and sustainability,” said Silva.
“We need to partner with companies to understand what their demands are and to work together. Conducting economic analysis, expanding scale or analyzing the market are not in our skill set, for example,” she said.
While they are seeking to broaden interactions with companies, the scientists are also seeking to use all available tools to develop good polymer-producing microorganisms. According to Silva, ongoing studies include the isolation of new microorganisms, the production of new mutants, and the use of metagenomics, metabolic engineering and synthetic engineering, among other approaches.
“We have to test everything that could possibly generate different polymers with different compositions, resulting in different properties that can broaden the applications of these materials. We are making every possible effort – both scientific and industrial – to develop sustainable and alternative biodegradable polymers,” she said.
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