Juan Daniel Rivaldi

Biosynthesis, characterization and enzymatic transesterification of single cell oil of Mucor circinelloides--a sustainable pathway for biofuel production.

The filamentous fungus Mucor circinelloides URM 4182 was tested to determine its ability to produce single-cell oil suitable for obtaining biodiesel. Cell growth and lipid accumulation were investigated in a medium containing glucose as the main carbon source. A microwave-assisted ethanol extraction technique (microwave power ⩽200 W, 50-60 °C) was established and applied to lipid extraction from the fungal hyphae to obtain high lipid concentration (44%wt) of the dry biomass, which was considerably higher than the quantity obtained by classical solvent methods. The lipid profile showed a considerable amount of oleic acid (39.3%wt), palmitic acid (22.2%wt) and γ-linoleic acid (10.8%wt). Biodiesel was produced by transesterification of the single-cell oil with ethanol using a immobilized lipase from Candida antarctica (Novozym® 435) as the catalyst. (1)H NMR and HPLC analyses confirmed conversion of 93% of the single-cell oil from M. circinelloides into ethyl esters (FAEE).

An Evaluation of Different Bioreactor Configurations with Immobilized Yeast for Bioethanol Production

The bioethanol industry expects a huge expansion and new technologies are being implemented with the aim of optimizing the fermentation process. The behavior of cells of Saccharomyces cerevisiae immobilized in PVA-LentiKats, during the production of bioethanol in two reactor systems, was studied. The entrapped cell in LentiKats lenses showed a different profile using stirred tank reactor (STR) and packed column reactor (PCR). Low free cells accumulation in the medium was observed for the STR after 72 h of fermentation. On the other hand, no free cells accumulation was observed, probably due to the absence of mechanical agitation in PCR configuration. Better fermentation results were obtained working with STR (final cellular concentration = 13 g.L-1, Pf = 28 g.L-1, Qp = 1.17 g.L-1.h-1,and Yp/s = 0.3 g.g-1) in comparison to PCR (final cellular concentration = 11.4 g.L-1, Pf = 20 g.L-1, Qp = 0.83 g.L-1.h-1,and Yp/s = 0.25 g.g-1). Such results are probably due to the mechanical agitation of the medium provided by STR configuration, which permitted a better heat and mass transference.

Assessing the potential of fatty acids produced by filamentous fungi as feedstock for biodiesel production

ABSTRACT Increased costs and limited availability of traditional lipid sources for biodiesel production encourage researchers to find more sustainable feedstock at low prices. Microbial lipid stands out as feedstock replacement for vegetable oil to convert fatty acid esters. In this study, the potential of three isolates of filamentous fungi (Mucor circinelloides URM 4140, M. hiemalis URM 4144, and Penicillium citrinum URM 4126) has been assessed as single-cell oil (SCO) producers. M. circinelloides 4140 had the highest biomass concentration with lipid accumulation of up to 28 wt% at 120 hr of cultivation. The profile of fatty acids revealed a high content of saturated (SFA) and monounsaturated fatty acids (MUFA), including palmitic (C16:0, 33.2–44.1 wt%) and oleic (C18:1, 20.7–31.2 wt%) acids, with the absence of polyunsaturated fatty acids (PUFA) having more than four double bonds. Furthermore, the predicted properties of biodiesel generated from synthesized SCOs have been estimated by using empirical models which were in accordance with the limits imposed by the USA (ASTM D6715), European Union (EN 14214), and Brazilian (ANP 45/2014) standards. These results suggest that the assessed filamentous fungus strains can be considered as alternative feedstock sources for high-quality biofuel production.

DESENVOLVIMENTO DE CATALISADOR ÓXIDO DE NIÓBIO SULFATADO PARA A SÍNTESE DE ÉSTERES ETÍLICOS A PARTIR ÓLEO DE ELEVADA ACIDEZ

RESUMO – A catálise ácida heterogênea representa uma alternativa à tradicional via alcalina para a produção de ésteres alquílicos a partir de óleos de alto conteúdo em ácidos graxos livres. Neste trabalho foi desenvolvido o catalisador óxido de nióbio sulfatado obtido por impregnação de óxido de nióbio com ácido sulfúrico (0,5 M) a 90°C sobre refluxo e agitação constante (500 rpm) por 3 h. O catalisador resultante foi submetido a tratamento térmico a 500°C por 5 h e caracterizado quanto à cristalinidade (XRD), morfologia (MEV) e acidez titulável (mmol H+/g). A reação de transesterificação foi conduzida com óleo de andiroba (índice de acidez: 33,1 mg KOH/g) e etanol anidro em condições variáveis de temperatura (160 – 260°C), relação molar óleo/etanol (1:50 – 1:120) e concentração de catalisador óxido de nióbio sulfatado de 5% (m/m). A conversão máxima do óleo de andiroba em ésteres etílicos foi de 67% à temperatura de 260°C e relação molar 1:120 óleo/etanol.