Mariana Manzoni Maroneze

The role of photoperiods on photobioreactors - A potential strategy to reduce costs.

The aim of this work was evaluate the role of photoperiods (long-term, frequencies and short) on the growth and lipid content of microalgae Scenedesmus obliquus CPCC05. The results showed that Scenedesmus obliquus can store sufficient energy to sustain cell growth for continuous periods of up to 2h in the dark, without affecting the photosynthetic rate. The values for maximum biomass (9.58mg/Lh) and lipid productivities (2.56mg/Lh) were obtained at photoperiod of 0.91:0.09s (light:dark) and 48 t/d, respectively. Moreover, the best trade-offs between biomass productivity and light energy economy occurred in photoperiods of 0.5:0.5s and 0.91:0.09s (light:dark), and those between lipid productivity and light energy economy occurred in the frequency photoperiod of 24 and 48 t/d. Thus, the use of the photoperiods are an effective strategy for reducing costs of microalgal biomass production.

Treatment of cattle-slaughterhouse wastewater and the reuse of sludge for biodiesel production by microalgal heterotrophic bioreactors

Microalgal heterotrophic bioreactors are a potential technological development that can convert organic matter, nitrogen and phosphorus of wastewaters into a biomass suitable for energy production. The aim of this work was to evaluate the performance of microalgal heterotrophic bioreactors in the secondary treatment of cattle-slaughterhouse wastewater and the reuse of microalgal sludge for biodiesel production. The experiments were performed in a bubble column bioreactor using the microalgae Phormidium sp. Heterotrophic microalgal bioreactors removed 90 % of the chemical oxygen demand, 57 % of total nitrogen and 52 % of total phosphorus. Substantial microalgal sludge is produced in the process (substrate yield coefficient of 0.43 mgsludge mgchemical oxygen demand−1), resulting in a biomass with high potential for producing biodiesel (ester content of more than 99 %, cetane number of 55, iodine value of 73.5 giodine 100 g−1, unsaturation degree of ~75 % and a cold filter plugging point of 5 oC).

Microalgal Production Systems with Highlights of Bioenergy Production

The purpose of this chapter is to provide an overview of the main systems of microalgae production with highlights of biofuel production. The large-scale production systems (raceway ponds, horizontal tubular photobioreactors, and heterotrophic bioreactors) and small-scale photobioreactors (vertical and flat-plate photobioreactors) will be presented and discussed with a special emphasis on the main factors affecting its efficiency, biomass productivities reported in the literature, scaling-up, costs of construction and operation, and commercial applications. Besides this, the recent developments in microalgae cultivation systems will be reviewed in their main aspects. Finally, the criteria for selecting an appropriate bioreactor for microalgae cultivation will be presented, as well as the pros and cons of each system will be discussed in this chapter.

Single-Cell Protein as a Source of Biologically Active Ingredients for the Formulation of Antiobesity Foods

Abstract The World Health Organization has defined obesity as a global public health problem. Several factors are responsible for the development of obesity; however, diets containing excessive macronutrients seem to play an important role in controlling body weight. Some authors have demonstrated the ability of proteins to affect food intake and appetite in humans, thus increased protein intake might promote weight loss and act against the development of obesity. However, the scarcity of protein-rich food has forced mankind to search for alternative protein sources that can replace conventional ones. Microalgae-based processing is a field of food bioengineering and is considered to be key to producing novel food ingredients with potential health benefits. This is largely due to the high-protein levels found in the biomass, in addition to the other components, such as fatty acids and pigments. The purpose of this chapter is to elucidate the use of microalgae biomass as a food ingredient, emphasize the ability of single-cell proteins to be used as antiobesity factors, and evaluate the feasibility of their inclusion in foods for the control of obesity.

Insights in cyanobacteria lipidomics: A sterols characterization from Phormidium autumnale biomass in heterotrophic cultivation

Sterol profiles were obtained from cyanobacteria Phormidium autumnale, cultivated in a heterotrophic system using three distinct sources of carbon: glucose, sucrose, and agroindustrial slaughterhouse wastewater. A simultaneous saponification-extraction ultrasound-assisted method was performed to determine sterol and other non-saponified compounds in the dry biomasses. A total of 24 compounds were observed in the biomasses, including hope-22,29-en-3-one, squalene, and 22 other sterols. Using wastewater as a carbon source, the microalgae biomass produced a diversity of sterols such as stigmasterol (455.3 μg g-1) and β-sitosterol (279.0 μg g-1). However, with glucose it is possible to produce ergosterol (1033.3 μg g-1). Squalene was found in all the cultures, with 1440.4 μg g-1, 225.4 μg g-1, and 425.6 μg g-1 for glucose, sucrose, and slaughterhouse wastewater biomasses, respectively. Several intermediate compounds from those sterols were found. These data provide the construction of the sterol metabolism according to the literature for P. autumnale heterotrophically cultured.

Polar and non-polar intracellular compounds from microalgae: Methods of simultaneous extraction, gas chromatography determination and comparative analysis

A method to simultaneously extract polar (PC) and non-polar compounds (NPC) from microalgae was developed for further determination of intracellular metabolites by gas chromatography. The proposed method was validated and used to characterize two Chlorophyceae, Chlorella vulgaris and Scenedesmus obliquus, and two Cyanobacteria, Aphanothece microscopica Nagëli and Phormidium autumnale. The compounds were extracted with a reduced amount of organic solvent mixture (methanol-chloroform), compared to the reference method, under different conditions of homogenization and/or cell disruption. The NPC were derivatized by acid catalysis, whereas the PC fraction was derivatized using N-methyl,N-tert-Butyldimethylsilyltrifluoroacetamide (MTBSTFA) in alkaline medium. The following parameters for method validation were considered: selectivity, linearity, limit of detection (LOD), limit of quantitation (LOQ), precision, and accuracy. All methods of homogenization and cell disruption extracted both PC and NPC from Chlorophyceae and Cyanobacteria. Derivatization of PC presented satisfactory validation parameters. Eleven fatty acids, six free amino acids, and three organic acids were found within the evaluated microalgae species, succinic, malic, and citric acids, important intermediates of the tricarboxylic acid cycle. Glutamic acid was the amino acid found in greatest quantities in all species. Chlorophyceae presented a higher concentration of unsaturated fatty acids, while Cyanobacteria had more saturated fatty acids. Thus, the proposed method was suitable to metabolically characterize both PC and NPC from microalgae.

Cassava processing wastewater as a platform for third generation biodiesel production

This study aimed to evaluate third generation biodiesel production by microalgae Phormidium autumnale using cassava processing wastewater as a platform. Experiments were performed in a heterotrophic bubble column bioreactor. The study focused on the evaluation of the bioreactor (batch and fed-batch) of different operational modes and the analysis of biofuel quality. Results indicate that fed-batch cultivations improved system performance, elevating biomass and oil productions to 12.0 g L−1 and 1.19 g L−1, respectively. The composition of this oil is predominantly saturated (60 %) and monounsaturated (39 %), resulting in a biodiesel that complys with U.S., European and Brazilian standards. The technological route developed indicates potential for sustainable production of bulk oil and biodiesel, through the minimization of water and chemical demands required to support such a process.