Biosíntesis de nuevos polihidroxialcanoatos (PHAs) en pseudomonas : desde la producción natural de biopolímeros en bacterias psicrófilas Antárticas hasta la modulación de rutas metabólicas a partir de glicerol
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Fecha
2020
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es
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Universidad Andrés Bello
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Licencia CC
Licencia CC
Resumen
El aumento sostenido en las ultimas décadas en la producción y utilización de plásticos
derivados del petróleo en el mundo, ha llevado a la generación de millones de
toneladas de desperdicios por año. Esto sumado a las casi nulas políticas de reciclaje
efectivo, dan como resultado que más del 80% del plástico utilizado tenga como
destino final el medioambiente. Es por esto, que se hace imperativo buscar una
alternativa sustentable para sustituir dichos polímeros sintéticos. En este ámbito,
bacterias ambientales son capaces de acumular moléculas intracelulares, denominados
biopolímeros, que aparecen como una alternativa de reemplazo para los plásticos
utilizados actualmente en el mundo. Ciertos microorganismos, son productores
naturales de dichos biopolímeros denominados específicamente como
polihidroxialcanoatos (PHAs). Los PHAs son polímeros de ácidos hidroxialcanoicos que
determinadas bacterias almacenan al interior de la célula como material de reserva,
para posteriormente ser utilizados como fuente de carbono y energía. Además de ser
biodegradables, los PHAs tienen características mecánicas y térmicas similares a los
termoplásticos convencionales como el polipropileno. Uno de los desafíos críticos para
la comercialización y globalización de estos biopolímeros es producir un PHA versátil,
que pueda ser generado mediante fermentación bacteriana utilizando materias primas
de bajo coste, y asi sea más rentable su producción respecto a los polímeros sintéticos.
En este trabajo, sintetizamos y caracterizamos nuevos PHA con propiedades únicas no
descritas anteriormente, mediante el uso de cepas del género Pseudomonas. Primero,
explotamos las bacterias productoras de PHA naturales aisladas del suelo antártico,
Pseudomonas frigusce/eri MPC6, que produjeron un nuevo polioxoéster de longitud de
cadena corta y media en glicerol a un alto nivel. Luego, diseñamos Pseudomonas
putida KT2440 genéticamente modificadas para sintetizar una estructura definida de
cadena polimérica de PHA utilizando glicerol como única fuente de carbono en cultivos
discontinuos. Tomando los resultados presentados aquí, llegamos a la conclusión de
que tanto la exploración de entornos extremos como el diseño racional en ingeniería
metabólica de rutas relacionadas al PHA, producen biopolímeros novedosos y
sostenibles que podrían reemplazar algunos de los productos de plástico sintético
convencional.
In the last decades, the sustained production and use of petroleum-based plastics in the world have led to the generation millions of tons of waste each year. Besides, the unsuccessful recycling policies result in more than 80% of the plastic used, ending up in the environment. Therefore, it is imperative to find a sustainable alternative to replace these synthetic polymers. In this concern, environmental bacteria have the ability to storage intracellular carbon molecules so-called biopolymers. These macromolecules have the potential to replace conventional plastics. Sorne microorganisms are natural producers of these biopolymers, specifically referred to as poly(3-hydroxyalkanoates) (PHA). PHAs are polymers of hydroxyalkanoic acids that store inside the cell as a reserve of carbon and energy, which can later be hydrolyzed by the cell to satisfy metabolic demands under famine conditions. In addition to being biodegradable, PHAs have mechanical and thermal properties similar to conventional thermoplastics such as propylene. One of the critica! challenges for its commercialization and globalization is to produce a versatile PHA, which can be manufactured via bacteria! fermentation using low-cost raw materials to make it more cost-competitive again synthetic polymers. In this work, we synthesized and characterized novel PHAs with unique properties not previously described before, through the use of strains of the genus Pseudomonas. First, we exploited the natural PHA-producing bacteria isolated from Antarctic soil, Pseudomonas frigusce/eri MPC6, which produced a new polyoxoester of short- and medium-chain length on glycerol at a high leve!. Then, we engineered Pseudomonas putida KT2440 to synthesize a defined structure of the polymeric chain of PHAs using glycerol as the sole source of carbon in batch cultures. Taking the results presented here, we conclude that both the exploration of extreme environments and the rational strain design via pathway engineering, yield novel and sustainable biopolymers that could replace sorne of the synthetic plastic products.
In the last decades, the sustained production and use of petroleum-based plastics in the world have led to the generation millions of tons of waste each year. Besides, the unsuccessful recycling policies result in more than 80% of the plastic used, ending up in the environment. Therefore, it is imperative to find a sustainable alternative to replace these synthetic polymers. In this concern, environmental bacteria have the ability to storage intracellular carbon molecules so-called biopolymers. These macromolecules have the potential to replace conventional plastics. Sorne microorganisms are natural producers of these biopolymers, specifically referred to as poly(3-hydroxyalkanoates) (PHA). PHAs are polymers of hydroxyalkanoic acids that store inside the cell as a reserve of carbon and energy, which can later be hydrolyzed by the cell to satisfy metabolic demands under famine conditions. In addition to being biodegradable, PHAs have mechanical and thermal properties similar to conventional thermoplastics such as propylene. One of the critica! challenges for its commercialization and globalization is to produce a versatile PHA, which can be manufactured via bacteria! fermentation using low-cost raw materials to make it more cost-competitive again synthetic polymers. In this work, we synthesized and characterized novel PHAs with unique properties not previously described before, through the use of strains of the genus Pseudomonas. First, we exploited the natural PHA-producing bacteria isolated from Antarctic soil, Pseudomonas frigusce/eri MPC6, which produced a new polyoxoester of short- and medium-chain length on glycerol at a high leve!. Then, we engineered Pseudomonas putida KT2440 to synthesize a defined structure of the polymeric chain of PHAs using glycerol as the sole source of carbon in batch cultures. Taking the results presented here, we conclude that both the exploration of extreme environments and the rational strain design via pathway engineering, yield novel and sustainable biopolymers that could replace sorne of the synthetic plastic products.
Notas
Tesis (Doctor en Biotecnología)
Palabras clave
Biopolímeros, Biosíntesis, Polihidroxialcanoatos