Banca de QUALIFICAÇÃO: PETRUCIA KARINE SANTOS DE BRITO BEZERRA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : PETRUCIA KARINE SANTOS DE BRITO BEZERRA
DATE: 04/03/2022
TIME: 09:00
LOCAL: Via Google Meet
TITLE:

BUTANOL PRODUCTION BY CLOSTRIDIUM BEIJERINCKII USING GREEN COCONUT LIGNOCELLULOSIC RESIDUE

KEY WORDS:
PAGES: 112
BIG AREA: Engenharias
AREA: Engenharia Química
SUBÁREA: Processos Industriais de Engenharia Química
SPECIALTY: Processos Bioquímicos
SUMMARY:

The search for renewable energies that minimize environmental damage, caused mainly by the burning of fossil fuels, has leveraged studies for the diversification of the world 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 sources, especially when the world seeks solutions to climate change. The green coconut shell, for example, is an abundant agro-industrial and urban waste that can be transformed into substrate and then converted into products of industrial value, adding value to the production chain, and solving environmental problems related to disposal. In this context, we investigated the potential of green coconut husk in the production of cellulosic butanol (or biobutanol) by ABE (Acetone-Butanol-Ethanol) fermentation, using Clostridium beijerinckii. However, this microorganism has a complex and anaerobic metabolic route, and it is necessary to verify the effect of factors relevant to the pre-treatment, enzymatic hydrolysis (EH) and fermentation steps. Thus, the behavior and recovery of cellulolytic enzymes remaining from green coconut shell (GCS) delignified by different pre-treatments (dilute acid, alkaline and acid-alkaline) were evaluated. Adsorption and desorption studies involving two types of cellulases (Trichoderma reesei ATCC 26921 and Cellic Ctec2, 10 FPU/g, initial dosage) with 5% solid filler showed that GCS delignified by alkaline (LCM1) and acid-alkaline (LCM3) showed lower cellulase adsorption capacity (48% and 69%); and higher cellulase recovery by desorption without addition of Tween 80 for LCM3 (reaching 50%).  Cellulases bound to the solid residue and dissolved in the supernatant after EH can be reused in a new cycle without compromising sugar yield results. Using GCS as a substrate, the addition of the solid residue and the supernatant from the previous cellulase adsorption stage reached satisfactory sugar yield g/g (73% for LCM1 and 60% for LCM3) only using the recycled enzyme (without addition of enzyme) in relation to the control assay. Thus, it was possible to recycle the cellulases in two successive cycles of HE with reduced enzymatic load to reach the same yields of reducing sugars (up to 84%), allowing a cheaper and more efficient hydrolysis of lignocellulosic biomass. ABE fermentation assays evaluated the influence of some nutrients, nitrogen sources and minerals on HCCV supplementation for the production of butanol and other solvents. It was found that ~9g/L of initial substrate (glucose + xylose) present in the hydrolyzate resulted in an ABE yield of 0.53g/g of LCM1, with 3.4g/L of butanol produced in 96h of fermentation, using concentration initial inoculum of 1g/L (bs). The absence or insufficiency of some nutrients (minerals and phosphate buffer) resulted in low ABE productions, indicating the relevance of the adequacy of supplements to the chosen fermentation medium and to the type of microorganism used.

BANKING MEMBERS:
Presidente - 1346198 - EVERALDO SILVINO DOS SANTOS
Externo à Instituição - CARLOS EDUARDO DE ARAÚJO PADILHA - UFRN
Externo à Instituição - PEDRO FERREIRA DE SOUZA FILHO