Tag-Archive for » enzymes «

segunda-feira, janeiro 25th, 2010 | Author: admin

O Brasil, que atualmente produz etanol basicamente a partir da cana-de-açúcar, poderá contar, no futuro, com novas possibilidades para produção do combustível. A Embrapa Cerrados – unidade da Empresa Brasileira de Pesquisa Agropecuária, localizada em Planaltina (DF) – coordenará a partir deste ano pesquisas para avaliar fontes de biomassa que podem ser usadas para produzir o chamado etanol de segunda geração.
Para isso, o projeto vai avaliar o uso de gramíneas forrageiras (usadas na alimentação animal), sorgo, o bagaço e a palha da cana e algumas espécies de árvores (pinus, eucalipto e duas espécies da Amazônia: tachi-branco e paricá), como fontes alternativas de biomassa para produção de etanol.
O etanol produzido a partir da cana-de-açúcar é obtido pela fermentação de açúcares presentes no caldo, obtido pela moagem da planta. Como resultado dessas pesquisas, a perspectiva é que açúcares complexos, como a celulose e hemicelulose existentes na composição das plantas, possam também ser convertidos no combustível, denominado etanol de segunda geração.
Segundo o pesquisador da Embrapa Cerrados Marcelo Ayres, que coordena o trabalho, a escolha das espécies para o estudo buscou contemplar plantas mais adaptadas às condições da região do Cerrado e que apresentem grande potencial de produção de biomassa. Outra vantagem é que já existem estudos anteriores que indicam o manejo desses cultivos. No caso das gramíneas forrageiras, por exemplo, a Embrapa lançou diversas cultivares de braquiária (foto), como a cultivar Marandu, que ocupa mais de 30 milhões de hectares no Brasil. “Ela é muito adaptada às condições climáticas do Cerrado e pode ser plantada até mesmo onde a cana não pode”, explica.
O processo de produção do etanol de segunda geração é composto por duas etapas. Na primeira delas as longas cadeias de celulose e hemicelulose são quebradas - por hidrólise enzimática ou química - para chegar a açúcares com cinco ou seis moléculas de carbono. Em uma segunda etapa, os açúcares reduzidos obtidos no processo de hidrólise são fermentados, assim como ocorre com a sacarose da cana-de-açúcar. Esse é o procedimento que os cientistas devem percorrer até chegar ao etanol. No entanto, a prática ainda é um desafio. “O mundo inteiro está trabalhando para definir quais as fontes e os processos a serem usados”, explica. Para o pesquisador, em relação a outras nações que estão na corrida para desenvolver a tecnologia do etanol de segunda geração, o Brasil tem a vantagem de estar em uma área tropical, o que favorece o desenvolvimento de biomassa.
A pesquisa vai reunir especialistas de universidades (Universidade de Brasília e Universidade de São Paulo) e de diversas unidades da Embrapa (Cerrados, Agroenergia, Floresta, Milho e Sorgo, Gado de Leite, Gado de Corte, Tabuleiros Costeiros, Instrumentação Agropecuária). Eles vão avaliar o potencial de produção de biomassa das espécies estudadas e também as características físico-químicas das plantas. Conduzida pelos pesquisadores da Embrapa Agroenergia, outra etapa do estudo vai pesquisar como converter essa biomassa em etanol, a partir da aplicação de enzimas que serão usadas em uma escala piloto.

segunda-feira, janeiro 25th, 2010 | Author: admin

Industrial biotechnology is gaining supporters among environmentalists as a way to make significant cuts in greenhouse-gas emissions and eventually move to a society free from fossil fuels.
The WWF estimated last September that industrial biotechnology has the potential to prevent emissions of between 1 and 2.5 billion tonnes of CO2 equivalent per year by 2030. The NGO sought to draw attention to such existing climate solutions that are easily overlooked by politicians and investors alike.
Enzymes have been added to detergents for decades to dissolve stains at lower temperatures. As a result, it is now possible to wash clothes at 30°C instead of 60°C with the same result, saving energy in the process.
Industries using agricultural products as input, such as food, paper and textiles, also currently use biotechnology to manufacture products using less energy and producing less waste, thus reducing pressure on land-use at the same time. Practical examples include adding enzymes to bread during baking to prolong its shelf-life, or using them in juice production to increase juice yield from the same quantity of fruit.

Towards advanced biofuels

The business is booming in the US, where corn-based production of bioethanol uses enzymes to release sugars from the starch in the kernels. The US Renewable Fuel Standard, passed in 2007, requires annual production to rise to 36 billion gallons of biofuel by 2022.
European markets are also growing, after 2009’s Renewable Fuels Directive set the target of reaching a 10% share of ‘green fuel’ in transport by 2020, including biofuels in this definition.
Lars Hansen, president of Novozymes Europe, says that interest in biotechnology is growing as halting global warming has become a political priority. The Danish company, the world leader in enzyme technology, estimates that its products helped to prevent emissions of 28 million tonnes of CO2 in 2008, the equivalent of taking four million cars off the road.
Nevertheless, there has been much debate over the actual environmental benefits of first-generation biofuels from food crops, as converting forests or grassland for energy crop production can release significant amounts of carbon. Advanced biofuels that use non-food feedstocks are now regarded as more promising, and the enzymes industry believes it holds the key to commercial-scale production.
“This has been the holy grail of biofuels: how can you move from using sugar and corn to using the straw, stalks and other agricultural waste?” said Novozymes executive Hansen.”We have directed 10% of our R&D resources into trying to convert not only starch but also agricultural leftovers into sugar,” Hansen said. “You get a much higher yield from the same acre of land by using what is currently perceived as waste, all the stuff left in the fields from agricultural production.”
Hansen said Novozymes is on track to delive the required technology this year. “We have the enabling technology ready, now someone has to build a factory using it.”
Corn ethanol is currently estimated to produce only a 12-18% net reduction in greenhouse gas emissions compared to gasoline, while cellulosic ethnanol could cut carbon emissions by 86-94%. If land-use changes are included in calculations, corn ethanol could actually double emissions, according to some estimates.

Towards a bio-based economy?
The ultimate goal of biotech supporters is to use enzyme technology to move to a “circular economy”. Here, waste is used to produce biogas while the remaining natural carbon could be reused as natural feedstock.The WWF estimated that such “closed loop systems,” which create new products from waste materials, could help trap up to three billion extra tonnes of carbon by 2040. Moreover, technological development would eventually lead to the replacement of oil-based products with natural materials in “biorefineries”.
“Biofuels are just a first step to what we call a ‘bio-based future’ where you replace traditional oil refineries with biorefineries,” Hansen said. “The vision is to have the same kind of refinery but based on biological production so that agricultural products go into producing not only fuels but plastics, feeds, fibres and chemicals.”

Background:
Biotechnology is divided into four branches:
* Green biotechnology is applied to agricultural processes and includes genetic modification of plants and animals.
* Red biotechnology is used in medicine to design organisms to produce antibiotics, for example.
* White, or industrial biotechnology, is used in industrial processes. It involves using organisms to produce valuable chemicals and using enzymes as catalysts to produce valuable chemicals or destroy harmful ones.
* Enzymes are used in a variety of industries, including food, textile, paper and agriculture, to increase the efficiency of processes.
The lofty idea behind industrial, or white, biotechnology is to use nature’s own ingredients to solve industrial problems. White biotech industries use enzymes - proteins that speed up chemical reactions - for various applications to increase efficiency of energy and raw-material use and eventually replace fossil fuels.

EurActiv