Future Directions

Cellulosic Ethanol from Sugarcane in Brazil

By | Blog, Future Directions, Global Change

sugarcane fieldBrazil is a major producer of ethanol from sugarcane, and this leading global position is the fruit of scientific and technological advances resulting from a development program that was initiated in the 1970s. Driven by the oil crises of 1972-1973, Brazil transformed several sugar mills into ethanol producing units that became capable of co-production of ethanol and raw sugar (5). This was technically possible due to the high levels of sucrose in sugarcane and to the development of yeast strains capable of fermenting this sugar efficiently. At the same time, the first automobiles running exclusively on ethanol were introduced, which on the one hand helped Brazil face major world energy crises, and on the other implanted the basis for development of future technologies. Over the following 40 years, Brazilian sugar mills undertook a technological transformation that significantly increased the efficiency of sucrose and alcohol production. This method, now called first generation (1G), has reached a level of 90% conversion of sucrose into ethanol (5). At the same time, advances in sugarcane agricultural technology improved the sugarcane crop to a high level of productivity (averaging 80 tones per hectare). Using intensive breeding programs, a number of sugarcane varieties have been developed that are increasingly better adapted to the diverse climate and soils encountered in Brazil. The result is that Brazil is now the second largest producer of ethanol and the first placed producer of sugarcane in the world.

The necessity to produce second-generation ethanol

Until 2006, Brazil was the only country to produce and use ethanol on a large scale as a fuel alternative for cars. Since then, increased public awareness and governmental focus around the world on issues related to climate change and the excessive use of fossil fuels has led to increased interest in the use of renewable energy. It was at this moment that Brazil, with its highly efficient sugarcane bioethanol sector, became a leader worldwide in the production and use of renewable energy. Nevertheless, production of 1G bioethanol was already at the limit of efficiency both from industrial and agronomical viewpoints.

It was in this context that the Brazilian scientific community and the Federal and State of São Paulo governments took the initiative in the search for ways to increase production of sugarcane ethanol beyond current limits. An idea that was already being revived in several places in the world was the possibility to produce ethanol from sugar polymers, including cellulose, present in cell walls of plants. This search for ‘cellulosic ethanol’ is generally referred to as second-generation (2G) ethanol. Although establishment of 1G technology was highly successful, the potential for ethanol production from 2G is much higher because energy accumulated in sugarcane in the form of sucrose represents only 1/3 of the total. The other two-thirds are distributed equally between the bagasse (stems) and the leaves.

Cell wall recalcitrance

At first sight, the idea of producing ethanol from biomass seems straightforward: it would be enough to convert cellulose to free sugars that could be fermented by yeast. Although many advances have been made in this area, this problem is far from being solved, and developing 2G processes that are economically viable has proven to be a major challenge. The plant cell wall is composed mainly of carbohydrates in the form of polysaccharides that associate to form a supramolecular structure where polymers aggregate through non-covalent linkages. Some polysaccharides are branched with phenolic compounds (ferulic an p-coumaric acids). Ferulic acid can dimerize interlocking polysaccharide chains or these can still undergo polymerization with other phenylpropanoids, including p-hydrocinammic, sinapyl and coniferyl alcohols, forming lignin. Together, the supramolecular structure of cell-wall polymers constitute the main obstacle to enzymatic hydrolysis. Furthermore, known hydrolytic enzymes have molecular sizes that prevent their penetration into the polymer matrix. Therefore, when a mixture of enzymes is added to the surface of the cell wall, the catalytic attack is mainly on the surface of the composite. To perform more complete hydrolysis, enzymatic complexes would have to act in a synergetic fashion on the entire cell wall composite. At present this is not feasible as researchers cannot adequately control the process because very little is known about the synergism between the enzymes involved. One of the principal limitations to understand such mechanisms is that until recently our knowledge of the structure and architecture of the sugarcane cell wall was very limited.

Sugarcane buckAt the biological level, cell wall recalcitrance in plants is thought to be due to the wall’ ability to protect against herbivores and the penetration of pathogens. At the molecular level, the cell wall of sugarcane presents three domains of polysaccharides that interact through non-covalent linkages: the pectic domain, the hemicellulosic domain and the cellulosic domain. The cellulosic domain is embedded within the hemicellulosic domain and both are embedded in the pectin domain. Thus, the basic unit of the cell wall of sugarcane consists of a core with macrofibrils (agglomerated of microfibrils) of cellulose strongly linked to structurally complex hemicelluloses that display a glycomic code, the complex branching pattern of these compounds (2). In addition, this core of polysaccharides is surrounded by an agglomerate of polymers that interact with themselves. Phenolic compounds are also thought to interlock the three polysaccharide domains so that the covalent linkages are protected, effectively sealing the whole unit and creating a structure that is extremely resistant to mechanical, chemical and biochemical degradation.

Several publications produced by the research labs of the National Institute of Science and Technology of Bioethanol (INCT-Bioetanol – have demonstrated that it is possible to disassemble the cell wall using chemical reagents (4). The procedure consists of initially attacking the phenolic compounds and eliminating them from the wall. This makes subsequent separation of the wall polysaccharides possible via treatment with a series of alkali solutions of increasing concentration (6).

A procedure called pretreatment (chemical and physical treatments with hot water, ammonia, acids and/alkali), eliminates the porosity barrier so that all polymers become accessible to attack by hydrolases. However, the branching nature of hemicelluloses still acts as a barrier and prevents further enzyme attack of the polymer chains. This highlights the necessity of using specific enzymatic complexes in order to produce free sugars that can be utilized for fermentation (1-7). As branched hemicelluloses alter the way polysaccharides are recognized by enzymes, their branching pattern (glycomic code) can alter the interaction between enzyme and substrate, affecting enzyme kinetics and cell wall degradation efficiency. The available data shows that the cell wall of sugarcane displays at least 18 glycosidic linkages, and suggests that approximately the same number of enzymes will be necessary to degrade the cell wall completely (5,6). Nevertheless, this chemical process is extremely complicated, laborious and expensive, and this is therefore not a viable strategy for industry.

The collection of enzymes characterized during the first phase of the INCT-Bioetanol contains practically all the catalytic capabilities needed for complete sugarcane cell wall hydrolysis. For this reason, the Institute has reached a point of prioritizing experiments focused on combining enzymes, forming consortia capable of dealing with each of the limiting factors related to recalcitrance. The possible combinations of enzymes have been proposed (1,6) and during the next phase of the project, these strategies will be put into practice by an integrated group of researchers in a series of experiments that will test this hypothesis.

At the same time, it will be necessary to understand the variability in the structure of the sugarcane cell wall in order to find Brazilian sugarcane varieties possessing structures and architectures that are more amenable to hydrolysis. Although the variation in cell wall composition is relatively limited among sugarcane tissues, one may expect to find considerable variation among the great number of extant varieties. This has been recently observed for Miscanthus and maize, two grass species that are genetically related to sugarcane and with very similar cell walls. Several research groups have concentrated efforts on understanding the role of lignin in recalcitrance and have concluded that this interference is somewhat limited. The reduction in lignin content leads in general to an increase in saccharification in a non-linear fashion depending on the pre-treatment, morphological distribution and the level of lignin aggregation (9), suggesting that other cell wall domains make equally important contributions to the recalcitrance of biomass. Research groups of the INCT-Bioetanol have already obtained transformed sugarcane in which the gene encoding one of the enzymes of lignin biosynthesis (COMT) has been silenced. These transgenic plants have cell walls that are modified, and saccharification tests are currently in progress. During the second phase of the INCT we intend to verify whether such genetic variability also exists in sugarcane and to use this information to obtain varieties in which differences among cell wall composition lead to lower recalcitrance to hydrolysis.


Marcos S. Buckeridge

Laboratory of Plant Physiological Ecology, Depatment of Botany, Institute of Biosciences, University of São Paulo (

Director of the National Institute of Science and Technology of Bioethanol (



  1. Buckeridge, M.S., Dos Santos,W.D., Tiné, M.A.S., De Souza, A.P. (2015) Compendium of Bioenergy Crops: Sugarcane edited by Eric Lam. CRC Press, Taylor and Francis (in press)
  2. Buckeridge, M.S. & De Souza, A.P. (2014) Breaking the “glycomic code” of cell wall polysaccharides may improve second generation bioenergy production from biomass. Bioenergy Research DOI 10.1007/s12155-014-9460-6
  3. Buckeridge, M.S.; Souza, A.P.; Arundale, R.A.; Anderson-Teixeira, K.J.; DeLucia, E. (2012) Ethanol from sugarcane in Brazil: a “midway” strategy for increasing ethanol production while maximizing environmental benefits. GCB Bioenergy, 4:119-126.
  4. Buckeridge, M. S. (Org.) ; Goldman, G. H. (Org.) . Routes to cellulosic ethanol. 1. ed. Nova Iorque: Springer, 2011. v. 1. 263p.
  5. De Souza, A. P. ; Grandis, A. ; Leite, D. C. C. ; Buckeridge, M.S. (2014) Sugarcane as a Bioenergy Source: History, Performance, and Perspectives for Second-Generation Bioethanol. Bioenerg Res, 7:24-35.
  6. De Souza, A. P., Leite, D. C. C., Pattathil, S. ; Hahn, M. G. ; Buckeridge, M. S. (2013) Composition and Structure of Sugarcane Cell Wall Polysaccharides: Implications for Second-Generation Bioethanol Production. Bioenergy Research, 6: 564-579.
  7. Mccann, M. ; Buckeridge, M. S. ; Carpita, N.C. . Plants and Bioenergy. 1. ed. New York: Springer, 2013. v. 1. 300p.
  8. Magrin, G.O., J.A. Marengo, J.-P. Boulanger, M.S. Buckeridge, E. Castellanos, G. Poveda, F.R. Scarano, and S. Vicuña, 2014: Central and South America. In: Climate Change 2014: Impacts, Adaptation, and Vulnerability. Part B: Regional Aspects. Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Barros, V.R., C.B. Field, D.J. Dokken, M.D. Mastrandrea, K.J. Mach, T.E. Bilir, M. Chatterjee,K.L. Ebi, Y.O. Estrada, R.C. Genova, B. Girma, E.S. Kissel, A.N. Levy, S. MacCracken, P.R. Mastrandrea, and L.L. White (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. XXX-YYY
  9. Rezende, C.A.; Lima, M.; Maziero, P.; Azevedo, E.; Garcia, W.; Polikarpov, I. (2011) Chemical and morphological characterization of sugarcane bagasse submitted to a delignification process for enhanced enzymatic digestibility. Biotechnology for Biofuels. 4: 54

Why nutrition-smart agriculture matters

By | Blog, Future Directions, Global Change

Orange Sweet PotatoThe focus of agricultural policy should be to increase productivity, provide employment and reduce poverty.

How often have you read or heard statements like this?

I am an economist, and I understand this thinking. It has its place. But I will argue that the reason global food systems are failing is because they have neglected the most fundamental purpose of agricultural systems — to nourish people.

Today, more than 2 billion people are suffering from hidden hunger — most will get enough calories, which has been the metric for food systems thus far, but not enough vitamins and minerals. We know too well the global costs of this hidden hunger. We see it in women as they risk death during childbirth. We see it in a stunted child with a diminished IQ. And we see it in men and women too weakened by illness and poor immunity to be able to work at an optimal level.

We need to re-envision agriculture as the primary source of sound nutrition through the food people harvest and eat. This is a radical concept in the true sense of the word — returning to the root or fundamental purpose of agriculture.

To read the rest of this blog post that was originally posted on Devex as part of the Feeding Development campaign, please click here.

This blog was written by Howdy Bouis who holds a joint appointment at the International Food Policy Research Institute in Washington, D.C. and the International Centre for Tropical Agriculture in Cali, Colombia.

“Children in Uganda share a plate of orange sweet potato” Photo used in this blog is by: A. Ball / HarvestPlus / CC BY-NC

“It’s the Economy, Stupid”: Understanding Agricultural Biotechnology

By | Blog, Future Directions

Plant scientists develop knowledge that may lead to new cultivars or products that have great potential to benefit agriculture, society, and research. Although these technologies often show immense promise in the lab or during experimental field trials they are not always adopted in the field. James Carville’s famed explanation of what determines the result of the US presidential election, “It’s the economy, stupid,” also applies to agricultural biotechnology. Research in agricultural economics is investigating what happens to these innovations beyond the experimental phase. Why are some of them succeeding while others are not? What is the social value of a given technology and what is its potential? Why are individuals and groups objecting to their introduction?

I have been working on agricultural biotechnology over the last decade, and there is quite a large body of literature on this topic. Two excellent surveys of the literature can be found in Qaim (2009) and Bennett et al. (2013). This blog focus on how technology affects agricultural productivity and profitability at the farm level, which helps to explain adoption choices, amount of food available, and food prices.

The first large-scale, commercially available agricultural biotechnologies to utilize genetic modification incorporated either pest-control traits, such as insect resistance through plant-producing Bt toxin, virus and oomycete resistance, or herbicide tolerance (to glyphosate). Such cultivars had the potential to increase output/edible yield by reducing damage and competition.

Agricultural economists have found that reasons and rates of adoption of such genetically modified (GM) cultivars vary among locations. In some cases, GM cultivars increase profits by increasing yields (mostly in developing countries where they address problems that have not been addressed before). In other cases, it increases profits because it leads to the reduction of alternative pest controls (mostly in developed countries). There is also significant evidence that many farmers have adopted GM cultivars not only because they have reduced pest infestation but also because the have reduced exposure to chemicals known to be toxic. For example studies of Bt-cotton in China have found that its adoption has actually saved lives in China (Huang, Pray, and Rozelle, 2002) There were several fatalities from the application of toxic chemicals agrichemicals, and these types of fatalities have significantly declined since the adoption of Bt-cotton.

cottonIn the case of Bt-cotton in China and Bt-maize in South Africa, adoption rates are considerably high and have also increased farmers’ profits significantly (greater than 50% in India (Subramanian and Qaim, 2009)). It is often thought (incorrectly) that the profits from GM-cultivars end up in the pockets of the large multinational corporations, instead our evidence indicates that they are shared among the providers of the technology (both the multinational corporations and local companies that sell it), the farmers, and the consumers. Consumer benefits also increase the greater the adoption rate, and the larger the price effect. In fact it is possible to distinguish between adopters who simply switch from traditional to GM-cultivars and those who expand production capacity because it becomes more profitable when growing GM cultivars. For example, in India, most cotton production has switched to Bt-cultivars and the share of global cotton production from India subsequently increased. In the case of soybeans global acreage has increased by more than 40% over the last 20 years, and most of this new acreage is growing GM-soybean. It should be noted that a large proportion of this expansion in soybean occurred through double-cropping in Argentina, Brazil and Paraguay, so the actual footprint of agriculture did not increase. Our studies estimate that the over supply of maize increased by about 10%, of cotton by 20%, and of soybeans by 30%. Without GM-soybeans, the price of soybeans is estimated to have been 33% higher on average, the price of maize 13% higher, and the price of cotton about 30% higher (Barrows, Sexton, and Zilberman, 2013).

800px-Soybean_fields_at_Applethorpe_FarmThe fact that GM-cultivars have already reduced the price of soybeans is very significant. While increases in commodity prices have little effect on consumers in the USA or EU, they affect consumers in developing countries quite substantially. Likewise, when supply decreases, consumers in the poorest countries around the world suffer most. We all remember the food price crisis of 2008. Without GM-crops, we would have experienced a much worse food situation. The increase in the supply of food provided by GM-crops is of the same order of magnitude as the amount of maize that is allocated to biofuel. If Europe and Africa adopted Bt-maize and soybeans, prices would decrease significantly and we would not face the food supply and access challenges that we face today. If we introduce existing traits to rice and wheat, the global food situation will improve, which will benefit poor producers and consumers the most. Moreover, since existing traits improve edible yields, they allow farmers to produce more on a given unit of land. Without GM-cultivars, we would need to employ more land in production, which translates to greater deforestation and increased greenhouse gas (GHG) emissions from more water and fertilizer use. The use of Roundup Ready soybeans enables the adoption of low-tillage farming practices, which leads to carbon sequestration (Lal, 2005). A conservative assessment suggests that the adoption of GM-crops reduced future GHG emissions by an amount equivalent to 1/8 of the level produced in a year by cars in the United States.

Agricultural biotechnology is in its infancy. The process to breed a new cultivar begins with researchers in companies and universities making new discoveries and seeking intellectual property such as patents or plant variety rights. Then, startups and companies invest in their development and commercialization. In the 1990s, the biotechnology industry was growing very fast. However, complex regulatory systems, particularly in the EU, have placed a heavy burdened on this process, drastically slowing the innovation process and in some cases even stalling the industry. As a result the technology is far from reaching its potential. In the pipeline alone, there are many innovations that can improve food quality, digestibility, nutritional intake, and shelf life. These technologies can be beneficial to consumers and, through increased efficiency of inputs such as land and water- They can also reduce the carbon footprint of agriculture. Heavy and uncertain regulation denies us from obtaining the benefits from these technologies. In many crops (e.g. fruits and vegetables), there has been minimal adoption of agricultural biotechnology, which reduces our ability to address disease and pest problems as well as achieving improved product quality. More importantly, we need as many tools as possible to adapt to climate change, drought, flood, extreme temperatures, unstable weather, and new pests. But, with stricter regulation and resistance to GM-crops, there will be limited investment in these technologies and our capacity to adapt to and mitigate climate change will be compromised. Economic research aims to assist governments in developing policies that will make consumers, producers, and the environment better off. The existing heavy regulation of agricultural biotechnology is very costly and thus suboptimal from an economic perspective.

This blog was provided by David Zilberman – Professor and Robinson Chair in the Department of Agricultural and Resource Economics at the University of California at Berkeley.



Barrows G., S. Sexton and D. Zilberman. 2013. “The impact of agricultural biotechnology on supply and land-use.” CUDARE Working Paper 1133, University of California, Berkeley.

Bennett, A.B., C. Chi-Ham, G. Barrows, S. Sexton and D. Zilberman. 2013. “Agricultural biotechnology: Economics, environment, ethics, and the future.” Annual Review of Environment and Resources 38: 249-279.

Huang, J., C. Pray and S. Rozelle. 2002. “Enhancing the Crops to Feed the Poor.” Nature 418:678– 684.

Lal, R. 2005. Soil erosion and carbon dynamics. Soil Tillage Research 81:137–142.

Qaim, M. 2009. “The economics of genetically modified crops.” Annual Review of Resource Economics 1: 665-694.

Subramanian, A. and M. Qaim. 2009. “Village-wide effects of agricultural biotechnology: the case of Bt cotton in India.” World Development 37:256–267.

A New Venture in Agriculture and Food Science: The World Food Center at UC Davis

By | Blog, Future Directions

WFCblogIn mid-2013 the University of California Davis announced establishment of the World Food Center (WFC) following extensive planning with input from a broad spectrum of university faculty and external advisors. There was broad agreement that the University could, and indeed should, strive to bring its leadership in food and agriculture research together to address specific global challenges in this arena. In doing so it would take a broad and trans-disciplinary approach to developing solutions to questions that the University is qualified to lead.

The Mission of the World Food Center is not simple:

The World Food Center will connect visionary research and teaching with innovators, philanthropists, industry, and public and social leaders to drive economic, health, social, and environmental value in the world’s food system.

tomsmallUC Davis is well known for outstanding research and teaching in disciplines that span food and agriculture, nutrition and health. Furthermore, work at the University has played a large role in the success of agriculture inside and outside the state. California’s agriculture is a vibrant industry based on production of more than 400 different crops as well as dairy and animal agriculture. The industry contributes more than $46 billion to the state economy. Since these crops contribute heavily to dietary diversity of consumers and provide essential nutrients, the University has developed outstanding research and education programs that span from molecular biology of crop and animal genomes and molecular breeding, seed biology, food sciences, enology and wine and other brewing sciences, sustainable agriculture, water management, post-harvest sciences, food safety, food sciences and food safety, nutrition (including the role of gut microbiome), health and wellness. It also includes substantial strengths in economics, social sciences and policy studies related to food and agriculture. Bringing this diversity of knowledge and technical skill to bear on grand challenges in food and agriculture (writ large) presents faculty and students with opportunities to have broader impacts on society than if single or even several disciplines are engaged. This is a goal of the WFC.

maizesmall2The World Food Center is not alone in striving to address grand challenges in food and agriculture, and other universities and research institutions around the globe have taken on similar goals, with variations. We suggest that during the next year a concerted effort be made to identify institutional initiatives with similar goals in developing ‘systems approaches’ to addressing challenges in food and agriculture. This exercise should lead to a more coordinated global effort that will minimize duplication of efforts while encouraging collaboration in research and training. And, it will increase the impacts of our efforts to address the grand challenges in food and agriculture.

If you are aware of other centers with goals similar to those of the World Food Center please contact us at

Roger N. Beachy, Executive Director, World Food Center, University of California, One Shields Avenue, Davis, CA 95616.