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Abstract
Previous studies have shown that pretreatment of corn slurries using ultrasound improves starch release and ethanol yield during biofuel production. However, studies on its effects on the mass transfer of substrates and products during fermentation have shown that it can have both beneficial and inhibitory effects. In this study, the effects of ultrasound on mass transfer limitations during fermentation were examined. Calculation of the external and intraparticle observable moduli under a range of conditions indicate that no external or intraparticle mass transfer limitations should exist for the mass transfer of glucose, ethanol, or carbon dioxide. Fermentations of glucose to ethanol using Saccharomyces cerevisiae were conducted at different ultrasound intensities to examine its effects on glucose uptake, ethanol production, and yeast population and viability. Four treatments were compared: direct ultrasound at intensities of 23 and 32 W/L, indirect ultrasound (1.4 W/L), and no-ultrasound. Direct and indirect ultrasound had negative effects on yeast performance and viability, and reduced the rates of glucose uptake and ethanol production. These results indicate that ultrasound during fermentation, at the levels applied, is inhibitory and not expected to improve mass transfer limitations.
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Valorization of Waste Glycerol to Dihydroxyacetone with Biocatalysts Obtained from Gluconobacter oxydans. APPLIED SCIENCES-BASEL 2018. [DOI: 10.3390/app8122517] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Waste glycerol is the main by-product generated during biodiesel production, in an amount reaching up to 10% of the produced biofuel. Is there any method which allows changing this waste into industrial valuable compounds? This manuscript describes a method for valorization of crude glycerol via microbial bioconversion. It has been shown that the use of free and immobilized biocatalysts obtained from Gluconobacter oxydans can enable beneficial valorization of crude glycerol to industrially valuable dihydroxyacetone. The highest concentration of this compound, reaching over 20 g·L−1, was obtained after 72 h of biotransformation with free G. oxydans cells, in a medium containing 30 or 50 g·L−1 of waste glycerol. Using a free cell extract resulted in higher concentrations of dihydroxyacetone and a higher valorization efficiency (up to 98%) compared to the reaction with an immobilized cell extract. Increasing waste glycerol concentration to 50 g·L−1 causes neither a faster nor higher increase in product yield and reaction efficiency compared to its initial concentration of 30 g·L−1. The proposed method could be an alternative for utilization of a petrochemical waste into industry applicated chemicals.
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Wu B, Liu Y, Liao W, Chen S. A numerical model for predicting diffusivity in a biocatalyst particle with heterogeneous reactions. AIChE J 2008. [DOI: 10.1002/aic.11542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Influence of immobilization parameters on endopolygalacturonase productivity by hybrid Aspergillus sp. HL entrapped in calcium alginate. Biochem Eng J 2006. [DOI: 10.1016/j.bej.2006.09.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Lactic acid fermentation by cells of Lactobacillus rhamnosus immobilized in polyacrylamide gel. World J Microbiol Biotechnol 2005. [DOI: 10.1007/s11274-005-9039-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Gutenwik J, Nilsson B, Axelsson A. Determination of protein diffusion coefficients in agarose gel with a diffusion cell. Biochem Eng J 2004. [DOI: 10.1016/j.bej.2003.09.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Current Awareness on Yeast. Yeast 2003. [DOI: 10.1002/yea.940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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