Banca de QUALIFICAÇÃO: THAIS DO CARMO OLIVEIRA SILVA

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : THAIS DO CARMO OLIVEIRA SILVA
DATE: 15/07/2026
TIME: 14:30
LOCAL: Via Google Meet
TITLE:

Production of lipid oils by Rhodosporidium toruloides using sugarcane molasses as a substrate aiming at obtaining biodiesel.

KEY WORDS:

Biodiesel; Rhodotorula toruloides; sugarcane molasses; microbial lipids.

PAGES: 98
BIG AREA: Engenharias
AREA: Engenharia Química
SUBÁREA: Processos Industriais de Engenharia Química
SPECIALTY: Processos Bioquímicos
SUMMARY:

The increasing demand for fuels and the environmental impacts associated with the use of fossil sources have driven the search for sustainable alternatives, among which third-generation biofuels stand out. In this context, this study aimed to evaluate the production and characterization of lipids by the yeast Rhodotorula toruloides CCT 0783 using hydrolyzed sugarcane molasses as a carbon and energy source, aiming at its subsequent application in biodiesel production. Molasses hydrolysis promoted an increase in the availability of fermentable sugars, increasing reducing sugars from 179.6 ± 0.57 g.L⁻¹ to 232.5 ± 0.70 g.L⁻¹. Then, a Central Composite Rotatable Design (CCRD) was carried out to evaluate the effects of molasses concentration and reaction volume on cell growth, sugar consumption, and lipid accumulation. The yeast showed growth under all evaluated conditions, with a predominant exponential phase between 24 and 48 h. The assays corresponding to the central points showed the highest cell counts, reaching values close to 1.9 × 10¹¹ cells/mL, indicating good experimental repeatability. However, the highest lipid accumulation was obtained in experiment 1, with 43.56 ± 0.83%, demonstrating that oil production was more related to the metabolic routing of carbon than only to biomass increase. This condition also showed the best kinetic performance, with a maximum specific growth rate of 0.0829 h⁻¹, a generation time of approximately 8.36 h, and cell productivity of 0.091 g.L⁻¹.h⁻¹. After scale-up of cultivation under this condition, 15.7 g of dry biomass and a lipid content of 42.21% were obtained, confirming the consistency of the result observed in the experimental design. The microbial oil showed an acid value of 21.88 mg KOH/g, a free fatty acid content of 11.0 ± 0.39%, a saponification value of 163.8 ± 1.97 mg KOH/g, and a water content of 0.35%. FTIR analysis confirmed the presence of functional groups characteristic of lipid materials, while GC-MS analysis indicated a predominance of oleic acid (35.39%) and palmitic acid (27.86%), a profile compatible with microbial oils of interest for biodiesel production. The results demonstrate that hydrolyzed sugarcane molasses is a promising substrate for the cultivation of R. toruloides CCT 0783 and for obtaining microbial oil. Considering the high acidity of the lipid fraction, the next stage of the work will consist of oil esterification, followed by biodiesel production.

COMMITTEE MEMBERS:
Interno - 1346198 - EVERALDO SILVINO DOS SANTOS
Interno - 1670497 - HUMBERTO NEVES MAIA DE OLIVEIRA
Interna - 3214434 - NATHALIA SARAIVA RIOS
Externa à Instituição - SINARA CYBELLE TURIBIO E SILVA NICODEMO - IFRN