Produção de polihidroxialcanoatos por Burkholderia glumae MA13: um conceito associado à indústria de biocombustíveis
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Data
2021-04-30
Autores
de Paula, Carolina Bilia Chimello [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Os polihidroxialcanoatos (PHAs) são poliésteres microbianos sintetizados como grânulos intracelulares por representantes dos domínios Bacteria e Archaea. Os PHAs são uma família de bioplásticos de origem biológica, totalmente biodegradáveis e compostáveis, gerando um solo rico em humus, além de ser biocompatíveis, característica atrativa para aplicações médicas e farmacêuticas. Os PHAs também atendem a especificações padrão para degradação em ambientes marinhos. Dessa forma, os PHAs são candidatos promissores para aplicações em produtos descartáveis ou de curta de vida de uso. Um conceito de biorrefinaria para biocombustíveis e bioplásticos tem sido proposto por vários autores como um processo integrado, com o objetivo de viabilizar ambas as indústrias como uma cadeia produtiva parcialmente ou totalmente independente dos derivados do petróleo. Neste contexto, Burkholderia glumae MA13 foi capaz de sintetizar PHAs a partir de fontes de carbono e subprodutos relacionados à indústria de biocombustíveis: sacarose; xilose; melaço, vinhaça e hidrolisado de bagaço de cana-de-açúcar; óleos de palma, babaçu, mamona e residual de fritura; e sebo bovino. Além disso, a produção de PHAs foi avaliada utilizando diferentes fontes de nitrogênio: (NH4)2SO4, (NH4)H2PO3, (NH4)2HPO3, NH4Cl, NaNO3, NH4NO3, ureia, extrato de levedura, autolisado de levedura e levedura seca inativa. Entre os insumos da indústria sucroalcooleira, o melaço sem pré-tratamento foi a melhor fonte de carbono, mesmo comparado à sacarose pura, com valores de acúmulo intracelular de polímero de 41-47% (m/m) da massa seca celular (% MSC). A adição de 25% (v/v) de vinhaça de cana-de-açúcar ao meio de cultivo contendo melaço resultou em valores de acúmulo de polímero de 45% MSC e um rendimento de 0,18 g/g, o que é econômico e ecologicamente interessante para a economia de água tratada para os processos industriais, além de oferecer um uso reciclado para a vinhaça, ao invés do descarte inapropriado deste subproduto em corpos de água e no solo. A produção de PHAs a partir de insumos relacionados à indústria de biodiesel resultou em um acúmulo intracelular máximo de polímero de 85% MSC a partir de óleo de palma. A produtividade volumétrica máxima de 0,16 g/(L.h) também foi obtida a partir deste insumo adicionado de uréia, após 56 h. A adição de ácido propiônico aos meios de cultivo resultou no copolímero P(3HB-co-3HV) com 18 e 21 mol% de 3HV em meios contendo óleo de babaçu e mamona, respectivamente. A atividade lipolítica foi detectada nos cultivos com insumos da indústria de biodiesel atingindo um valor máximo de 481 U/mL. A análise por espalhamento de luz estático (SLS) apresentou polímeros com massas moleculares médias variando de 1,3 x 105 a 2,7 x 105 Da. A calorimetria exploratória diferencial (DSC) revelou polímeros com temperaturas de fusão em uma faixa de 147-165°C, e a análise termogravimétrica (TGA) mostrou temperaturas iniciais de degradação térmica de 230-297 °C. Neste estudo, B. glumae MA13 demonstrou ser uma linhagem bacteriana promissora para a síntese de PHAs a partir de diferentes insumos relacionados à indústria de biocombustíveis, favorecendo um conceito de biorrefinaria com bioprodutos agregados à cadeia de produção de biocombustíveis, com benefícios ecológicos em um modelo sustentável.
Polyhydroxyalkanoates (PHAs) are microbial polyesters synthesized by representatives of Bacteria and Archaea domains as intracellular granules. Beyond microbial adaptation strategies, PHAs are a family of bioplastics which are fully bio-based and biodegradable. Additionally, PHAs are compostable resulting in humus-rich soil and these microbial polymers also are biocompatible, which is attractive for pharmaceutical and medical applications such as nanobeads for drug delivery systems and nanofiber scaffolds for tissue engineering. Furthermore, PHAs meet the standard specification for marine degradability. All these mentioned features make PHAs promising candidates for short-lived and disposable applications. A biorefinery concept for biofuels and bioplastics has been proposed by many authors as an associated production set in order to generate value-added chemicals, especially those obtained from common feedstocks or biofuel byproducts, in order to support such industries as production set partially or totally independent of petrochemical derivatives. In this sense, Burkholderia glumae MA13 was able to synthesize PHA bioplastics from carbon sources and industrial byproducts related to biofuel industries: sucrose; xylose; sugarcane molasses, vinasse and bagasse hydrolysate; palm, babassu, castor and waste cooking oils; and bovine tallow. Moreover, PHA production was tested using different nitrogen sources: (NH4)2SO4, (NH4)H2PO3, (NH4)2HPO3, NH4Cl, NaNO3, NH4NO3, urea, yeast extract, yeast autolysate and inactivated dry yeast. Among bioethanol related feedstocks, molasses free of pre-treatment was the best carbon source, even compared with pure sucrose, with intracellular polymer accumulation values of 41-47% (w/w) cell dry weight (% CDW). The addition of 25% (v/v) sugarcane vinasse to the culture media containing molasses was not deleterious and resulted in a statistically similar maximum polymer content of 45% CDW and a polymer yield of 0.18 g/g, which is economic and ecologically interesting to save water required for industrial processes and to offer a fermentative recycling for vinasse, as an alternative to its inappropriate disposal in water bodies and soil contamination. PHA production from biodiesel related feedstocks resulted in a maximum intracellular polymer accumulation of 85% CDW from palm oil. Maximum volumetric productivity of 0.16 g/(L.h) was also obtained from palm oil and urea after 56 h. Addition of propionic acid to the culture media resulted in the copolymer P(3HBco- 3HV) with a 3HV content of 18 and 21 mol% in cultivation media containing babassu and castor oils, respectively. Lipase activity was detected in biodiesel feedstock cultivations with a maximum value of 481 U/mL. Static light scattering analysis showed average molecular weight values of polymers synthesized by B. glumae MA13 ranging from 1,3 x 105 to 2,7 x 105 Da. Differential scanning calorimetry (DSC) analysis revealed polymers with melting temperatures in the range of 147-165 °C, and thermogravimetric analysis (TGA) showed onset decomposition temperatures of 230-297 °C. B. glumae MA13 has been demonstrated to be a promising bacterial strain to synthesize PHA bioplastics from different biofuel related feedstocks and corroborates to support a biorefinery concept with value-added green chemicals for biofuel productive chain with additional ecologic benefits into a sustainable model.
Polyhydroxyalkanoates (PHAs) are microbial polyesters synthesized by representatives of Bacteria and Archaea domains as intracellular granules. Beyond microbial adaptation strategies, PHAs are a family of bioplastics which are fully bio-based and biodegradable. Additionally, PHAs are compostable resulting in humus-rich soil and these microbial polymers also are biocompatible, which is attractive for pharmaceutical and medical applications such as nanobeads for drug delivery systems and nanofiber scaffolds for tissue engineering. Furthermore, PHAs meet the standard specification for marine degradability. All these mentioned features make PHAs promising candidates for short-lived and disposable applications. A biorefinery concept for biofuels and bioplastics has been proposed by many authors as an associated production set in order to generate value-added chemicals, especially those obtained from common feedstocks or biofuel byproducts, in order to support such industries as production set partially or totally independent of petrochemical derivatives. In this sense, Burkholderia glumae MA13 was able to synthesize PHA bioplastics from carbon sources and industrial byproducts related to biofuel industries: sucrose; xylose; sugarcane molasses, vinasse and bagasse hydrolysate; palm, babassu, castor and waste cooking oils; and bovine tallow. Moreover, PHA production was tested using different nitrogen sources: (NH4)2SO4, (NH4)H2PO3, (NH4)2HPO3, NH4Cl, NaNO3, NH4NO3, urea, yeast extract, yeast autolysate and inactivated dry yeast. Among bioethanol related feedstocks, molasses free of pre-treatment was the best carbon source, even compared with pure sucrose, with intracellular polymer accumulation values of 41-47% (w/w) cell dry weight (% CDW). The addition of 25% (v/v) sugarcane vinasse to the culture media containing molasses was not deleterious and resulted in a statistically similar maximum polymer content of 45% CDW and a polymer yield of 0.18 g/g, which is economic and ecologically interesting to save water required for industrial processes and to offer a fermentative recycling for vinasse, as an alternative to its inappropriate disposal in water bodies and soil contamination. PHA production from biodiesel related feedstocks resulted in a maximum intracellular polymer accumulation of 85% CDW from palm oil. Maximum volumetric productivity of 0.16 g/(L.h) was also obtained from palm oil and urea after 56 h. Addition of propionic acid to the culture media resulted in the copolymer P(3HBco- 3HV) with a 3HV content of 18 and 21 mol% in cultivation media containing babassu and castor oils, respectively. Lipase activity was detected in biodiesel feedstock cultivations with a maximum value of 481 U/mL. Static light scattering analysis showed average molecular weight values of polymers synthesized by B. glumae MA13 ranging from 1,3 x 105 to 2,7 x 105 Da. Differential scanning calorimetry (DSC) analysis revealed polymers with melting temperatures in the range of 147-165 °C, and thermogravimetric analysis (TGA) showed onset decomposition temperatures of 230-297 °C. B. glumae MA13 has been demonstrated to be a promising bacterial strain to synthesize PHA bioplastics from different biofuel related feedstocks and corroborates to support a biorefinery concept with value-added green chemicals for biofuel productive chain with additional ecologic benefits into a sustainable model.
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Palavras-chave
PHA, Bioplástico, Biodiesel, Bioetanol, Sustentabilidade, Bioplastic, Bioethanol, Sustainability