Studies seek better ways to use biomass

Brazilian scientists at FAPESP Week Belgium present approaches that attempt to solve challenges involving the use of biomass in a sustainable economy.

By Heitor Shimizu, in Brussels (Belgium)  |  Agência FAPESP – Sustainable development is “development that meets the needs of the present without compromising the ability of future generations to meet their own needs,” according to the report published in 1987 by the Brundtland Commission, which later adopted the name World Commission on Environment and Development.

The report, entitled Our Common Future, suggests a series of measures countries can take to promote sustainable development, including the development of technologies that use renewable sources of energy.

Brazil is one of the countries that makes the most use of renewable energy sources and, in addition, does not depend on oil for its vehicles to the same extent as other countries. This is due to the use of biofuels, in particular, ethanol, made from the juice extracted from sugarcane. But there is another type of ethanol that offers immense potential: cellulosic ethanol, obtained from sugarcane byproducts (bagasse and straw) and also known as second generation ethanol.

Cellulosic ethanol is one of the most important examples of the use of lignocellulosic biomass to produce renewable liquid fuels.

“It is the consensus that a sustainable economy will rely on a multiplicity of energy sources, with biomass playing an important role,” said Roberto de Campos Giordano, full professor at the Chemical Engineering Department of the Federal University of São Carlos (UFSCar), at FAPESP Week Belgium, held in the cities of Brussels, Liège and Leuven October 8-10, 2018.

“Furthermore, biorefineries will have to produce molecules and monomers, which combine to form polymers, to replace oil derivatives. Yet an important gap remains to be bridged: how do we make this transition in the real economy feasible?” said Giordano, who directs the Laboratory for the Development and Automation of Bioprocesses, and who spoke at the event about the contribution of process and systems engineering in making the use of biomass in a low carbon economy feasible.

According to Giordano, much work remains to be done on two fronts: the development of advanced bioprocesses and the development of computational tools that “support techno-economic-environmental feasibility analysis from the very start of research into low carbon impact production processes.”

Both aspects are being addressed by an interinstitutional group of eight laboratories working on the Thematic Project “From the cell factory to the biodiesel-bioethanol integrated biorefinery: a systems approach applied to complex problems in micro and macroscales”, led by Giordano and included as under the scope of the FAPESP Bioenergy Research Program (BIOEN).

“The project seeks to confront technological challenges posed by a new conception of an integrated biorefinery, taking advantage of synergies between the production processes of the two most important biofuels in the Brazilian context: first and second generation bioethanol from sugarcane, and biodiesel from plant oils as well as from microbial sources,” he said.

“For this reason, we assembled researchers with extensive experience in the field, from several institutions in the state of São Paulo. Renewable sources of liquid biofuels form “the backbone of that biorefinery, based on biochemical pathways, although the production of value-added molecules is also being investigated,” he said.

The Thematic Project brings together several lines of research such as: synthesis, optimization and techno-economic-environmental analysis integrated through simulation of the bioethanol refinery; obtaining added-value biomolecules from byproducts of the biofuel production process and/or of biomass present in the biorefinery; and integrating the production processes of second generation ethanol and ethyl biodiesel, using byproducts from the production of fuels as feedstock.

Fungi that like the heat

Biomass is an abundant source of polysaccharides–carbohydrates composed of small molecules of sugar – such as cellulose – that can be used as renewable feedstock for the production of such things as biofuels (like second generation ethanol) and green chemistry compounds (fertilizers).

“The problem is that the conversion of these polysaccharides into sugars that can be fermented by enzymatic means is still a lengthy and expensive process,” said Fernando Segato, professor at the University of São Paulo Engineering School of Lorena (EEL-USP), during FAPESP Week Belgium.

Segato spoke at the Brussels event about the use of enzymes produced by fungi that survive at high temperatures in the production of sugars from lignocellulosic biomass, composed of lignin, hemicellulose and cellulose.

“The production of biofuels and other chemical compounds from renewable materials like lignocellulosic biomass is difficult, mainly due to its recalcitrance to deconstruction. This recalcitrance is mostly due to the presence of lignin in plant cell walls,” he said.

Lignin is a macromolecule found in dry land plants. It is associated with hemicellulose and cellulose in the cell wall and its purpose is to impart rigidity, impermeability and resistance to biological and mechanical attacks.

“Lignin can be broken down or removed from plant cell walls through expensive treatments that use harsh chemicals, high temperatures and high pressure. While the lignin in lignocellulosic biomass resists attack from microorganisms, some fungi produce enzymes that are able to degrade lignin,” he said.

As a result of this, the group led by Prof. Segato is investigating the use of enzymes produced by thermophilic fungi (or thermophiles) in the degradation of lignin. Those microorganisms are able to survive at high temperatures above 45°C. Some of them (hyperthermophiles) can withstand temperatures close to 70°C. Among the principal species studied by the researchers are Aspergillus niveus (recently reclassified as A. fumigatus var niveus) and Myceliophthora thermophila.

The study is funded by FAPESP and led jointly by scientists from USP, the Brazilian Center for Research in Energy and Materials (CNPEM), São Paulo State University (Unesp), the University of Nebraska in Lincoln (UNL), where Segato was a visiting professor, and Oklahoma State University (OSU).

According to Segato, mechanisms to degrade lignocellulosic materials were identified by analyzing thermophilic fungi transcriptomes (the set of RNAs of an organisms, organ, tissue or cell line) and secretomes (set of secreted proteins). “When the enzymatic extracts of different species were mixed, there was a 2.5-fold increase in biomass saccharification,” he said.

“Those findings led our group to investigate the enzymes that could be acting collaboratively to improve lignocellulosic biomass saccharification. For this, we used techniques of high throughput analysis, molecular biology and heterologous protein expression as tools to better understand the enzymatic interaction that led to the increase in lignocellulosic biomass saccharification,” he said.  

Held at the Brussels Comic Book Museum, the event is organized by FAPESP together with Belgian organizations F.R.S.-FNRS, the Department of Economy, Science and Innovation (EWI), the Research Foundation Flanders (FWO) and the Wallonie-Brussels International (WBI).

For additional information, visit: www.fapesp.br/week2018/belgium.