Produção de biobutanol por fermentação acetona-butanol-etanol (ABE) utilizando Clostridium beijerinckii ATCC 10132 a partir do hidrolisado enzimático da casca de coco verde
The search for renewable energies that minimize the environmental damage caused mainly by the burning of fossil fuels has encouraged studies for the diversification of the global energy matrix. In the case of Brazil, the insertion of new biofuels such as butanol associated with the valorization o...
Spremljeno u:
| Glavni autor: | |
|---|---|
| Daljnji autori: | |
| Format: | doctoralThesis |
| Jezik: | pt_BR |
| Izdano: |
Universidade Federal do Rio Grande do Norte
|
| Teme: | |
| Online pristup: | https://repositorio.ufrn.br/handle/123456789/52768 |
| Oznake: |
Dodaj oznaku
Bez oznaka, Budi prvi tko označuje ovaj zapis!
|
| Sažetak: | The search for renewable energies that minimize the environmental damage caused mainly by
the burning of fossil fuels has encouraged studies for the diversification of the global energy
matrix. In the case of Brazil, the insertion of new biofuels such as butanol associated with the
valorization of lignocellulosic biomass presents an opportunity to consolidate its historical
vocation in the leadership of renewable energy sources. Green coconut husk (GCS) is an
abundant agro-industrial waste that can be converted into value-added products while solving
environmental problems caused by its inappropriate disposal. In this context, the potential of
the GCS was investigated in the production of cellulosic butanol (or biobutanol) by ABE
(Acetone-Butanol-Ethanol) fermentation, using Clostridium beijerinckii. Initially, enzymatic
hydrolysis tests were carried out to evaluate the release of sugars and the ability to recycle
commercial cellulolytic cocktails. The behaviour and recovery of cellulolytic enzymes
remaining from pre-treated GCS (by dilute acid, alkali, and acid-alkali) were evaluated.
Additionally, batch fermentation tests were performed to investigate the influence of some
nutrients (nitrogen sources and mineral medium) as supplements on the hydrolysate to produce
butanol and other solvents. Fed batch fermentation was performed in order to improve butanol's
yield and productivity. Adsorption studies from cellulases showed that pre-treated GCS by
alkali ensure large amount of free cells (52% for Trichoderma reesei cocktail and 69% for
Cellic CTEC2 cocktail) and greater susceptibility of desorption with buffer (~50%). Sugar
yields greater than 60% were obtained using recycled enzymes from solid and liquid fractions.
Recycling enzymes by two cycles hardly affected the catalytic capacity in the pre-treated GCS
hydrolysis by alkali, and acid-alkali. Using hydrolysate with 9 g/L of sugars (glucose + xylose),
the fermentation ABE reached a yield of 0.53 g/g after 96 h, in which 3.4 g/L of butanol were
obtained. The absence or insufficiency of some nutrients (minerals and phosphate buffer)
resulted in low yield of ABE products, indicating the relevance of the adequacy of supplements to the chosen fermentation medium, and the type of microorganism used. Fed batch increased
productivity in ABE fermentation (0.08 g/L.h butanol). The results indicate that green coconut
waste has potential to contribute to the energy sector and is a low-cost raw material for the
biotechnological production of butanol, as an alternative and renewable product |
|---|