ABSTRACT
The bioethanol production from the sweet potato variety BRS Cuia using three different strains of Saccharomyces cerevisiae (LPB1-93, ATCC-26602, and CA-11) was carried out in this research. Comparative analyses of consumed sugar, ethanol yield, and productivity (in tons per hectare) increased along with the concentration of cells in the inoculum. Additionally, to verify the aromatic quality of a potential sweet potato distilled spirit, volatile organic compounds were analyzed. The results showed a yield of over 90% ethanol. It was observed that the sugar consumption and ethanol production rates can be increased with a higher initial concentration of cells. This resulted in higher concentrations of ethanol in shorter times. From 100 g of the sweet potato variety BRS Cuia, the highest concentration of ethanol obtained was 25.74 g L-1 using the LPB1-93 strain. The estimated bioethanol production is about 10,000 L ha-1, with two sweet potatoes crops in a year. The ethanol production from the sweet potato variety BRS Cuia is viable, representing a sustainable alternative to fuel bioethanol, as well as an alcoholic beverage due to the volatile organic compounds present in the distilled fraction.
ABSTRACT
Microalgae are versatile sources of bioproducts, a solution for many environmental problems. However, and despite its importance, one of the main problems in large-scale cultures-the presence of contaminants-is rarely systematically approached. Contamination, or the presence of undesirable organisms in a culture, is deleterious for the culture and frequently leads to culture crashes. To avoid contamination, closed systems can be used; however, for very large-scale open systems, contamination is unavoidable and remediation procedures are necessary-ranging from physicochemical treatment to addition of biocidal substances. In all cases, early detection and culture monitoring are paramount. This article describes the biological contaminants, contamination mechanisms, and control systems used in open and closed cultures, discussing the latest advances and techniques in the area. It also discusses the complex interactions of algae with other microorganisms that can be expected in cultivation systems.
