Extração de xilana do bagaço de cana-de-açúcar microbiologicamente pré-tratado
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Data
2020-02-20
Autores
Felipuci, Jefferson Poles [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
O bagaço de cana-de-açúcar é um subproduto proveniente da moagem do colmo para extração de caldo de sacarose. Suas principais aplicações são na área energética, mas pode ser reaproveitado na geração de produtos de maior valor agregado. Para isto, a separação de suas macromoléculas é um passo fundamental no processo, visto que os métodos empregados industrialmente utilizam grandes cargas de reagentes químicos ou demandam muita energia. Micro-organismos são uma alternativa a estes métodos, suas capacidades naturais de degradação são uma opção para reduzir o custo destes processos e diminuir a quantidade de reagentes químicos. A combinação do pré-tratamento biológico com o químico é uma alternativa para aumentar o rendimento na extração dos componentes da biomassa e reduzir custos. Neste contexto, este trabalho teve como objetivo aplicar o tratamento microbiológico previamente ao tratamento químico na decomposição do bagaço de cana-de-açúcar, a fim de avaliar o grau de deslignificação do material e, com isso, verificar este efeito no processo de extração de xilana utilizando menor carga de reagente químico, bem como avaliar a digestibilidade enzimática do material pré-tratado. Os fungos Coniophora puteana, Gloeophyllum trabeum, Aspergillus fumigatus e Pleurotus ostreatus foram cultivados até cinco meses em sacos de polipropileno contendo 250 g de bagaço de cana-de-açúcar a 75 % de umidade. O material parcialmente deslignificado foi submetido à caracterização química e à extração de xilana com peróxido de hidrogênio (3 %). Após o tratamento microbiológico foi feita a hidrólise enzimática do material para verificar a conversão de celulose em glicose. A caracterização química apontou aumento percentual no teor de lignina nos materiais para todas as amostras, ao mesmo tempo que diminuiu a porcentagem de celulose e hemicelulose. Apenas o experimento referente à A. fumigatus não atingiu resultado superior a extração de xilana do bagaço in natura, com porcentagem média de extração igual a 30,31 %. Por outro lado, a porcentagem de extração referente à G. trabeum e C. puteana foram superiores a extração de xilana do bagaço in natura, chegando a 99,74 %. Os resultados referentes à conversão da celulose em glicose mostraram que o melhor período de tratamento foi de um mês, com 65 % conversão. O trabalho constatou que, embora os micro-organismos tenham consumido parte da xilana do material, houve modificação na estrutura lignocelulósica, facilitando a extração da xilana residual e melhorou a digestibilidade enzimática da celulose
Sugarcane bagasse is a by-product acquired from milling the stalk for saccharose broth extraction. Its main applications are not only in the energy area, but also in the generation of higher added value products. For this, the separation of its macromolecules is a fundamental step in the process, provided that the methods employed industrially use large loads of chemical reagents or demand a lot of energy. As an alternative to those methods, microorganisms present natural degradation capabilities which might cheapen such procedures and reduce the amount of chemical reagents. Thus, the combination of biological pretreatment and chemical pretreatment is an option to increase the extraction yield of biomass components and reduce costs. In this context, this work aimed to apply the microbiological treatment prior to the chemical one in the decomposition of sugarcane bagasse, in order to evaluate the degree of delignification of the material and, thereby, verify the effect in the xylan extraction process while applying lower chemical reagents loading, as well as evaluating enzymatic digestibility of pretreated material. The fungi Coniophora puteana, Gloeophyllum trabeum, Aspergillus fumigatus and Pleurotus ostreatus were grown for up to five months in polypropylene bags containing 250 g of sugarcane bagasse at 75 % of humidity. The partially delignified material was subjected to chemical characterization and xylan extraction with hydrogen peroxide (3%). Following the microbiological treatment, enzymatic hydrolysis of the material was performed to verify the cellulose conversion to glucose. The chemical characterization presented a percentage increase in the lignin content in the materials for all samples, whereas the percentage of cellulose and hemicellulose decreased. Only the experiment related to A. fumigatus did not reach greater result than the in natura bagasse xylan extraction, with average extraction percentage of 30.31%. On the other hand, the xylan extraction percentage for G. trabeum and C. puteana were higher than the in natura bagasse value, which reached 99.74%. The results regarding the conversion rate of cellulose to glucose reported that the best treatment period was one month, with 65 % conversion. Although the microorganisms consumed part of the material's xylan, this study noted a change in the lignocellulosic structure, facilitating residual xylan extraction and improving enzymatic digestibility of cellulose.
Sugarcane bagasse is a by-product acquired from milling the stalk for saccharose broth extraction. Its main applications are not only in the energy area, but also in the generation of higher added value products. For this, the separation of its macromolecules is a fundamental step in the process, provided that the methods employed industrially use large loads of chemical reagents or demand a lot of energy. As an alternative to those methods, microorganisms present natural degradation capabilities which might cheapen such procedures and reduce the amount of chemical reagents. Thus, the combination of biological pretreatment and chemical pretreatment is an option to increase the extraction yield of biomass components and reduce costs. In this context, this work aimed to apply the microbiological treatment prior to the chemical one in the decomposition of sugarcane bagasse, in order to evaluate the degree of delignification of the material and, thereby, verify the effect in the xylan extraction process while applying lower chemical reagents loading, as well as evaluating enzymatic digestibility of pretreated material. The fungi Coniophora puteana, Gloeophyllum trabeum, Aspergillus fumigatus and Pleurotus ostreatus were grown for up to five months in polypropylene bags containing 250 g of sugarcane bagasse at 75 % of humidity. The partially delignified material was subjected to chemical characterization and xylan extraction with hydrogen peroxide (3%). Following the microbiological treatment, enzymatic hydrolysis of the material was performed to verify the cellulose conversion to glucose. The chemical characterization presented a percentage increase in the lignin content in the materials for all samples, whereas the percentage of cellulose and hemicellulose decreased. Only the experiment related to A. fumigatus did not reach greater result than the in natura bagasse xylan extraction, with average extraction percentage of 30.31%. On the other hand, the xylan extraction percentage for G. trabeum and C. puteana were higher than the in natura bagasse value, which reached 99.74%. The results regarding the conversion rate of cellulose to glucose reported that the best treatment period was one month, with 65 % conversion. Although the microorganisms consumed part of the material's xylan, this study noted a change in the lignocellulosic structure, facilitating residual xylan extraction and improving enzymatic digestibility of cellulose.
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Palavras-chave
Micro-organismos, Cana-de-açúcar, Hemicelulose, Microbiologia, Fungos, Microbiology, Hemicellulose, Micro-organisms, Wood fungi, Sugarcane, Xilana, Pré-tratamento microbiológico, Recalcitrância, Bagaço de cana-de-açúcar, Xylan, Microbiological pretreatment, Recalcitrance, Sugarcane bagasse