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1.
Chinese Journal of Biotechnology ; (12): 429-447, 2021.
Article in Chinese | WPRIM | ID: wpr-878573

ABSTRACT

Higher alcohols are one of the main by-products of Saccharomyces cerevisiae in brewing. High concentration of higher alcohols in alcoholic beverages easily causes headache, thirst and other symptoms after drinking. It is also the main reason for chronic drunkenness and difficulty in sobering up after intoxication. The main objective of this review is to present an overview of the flavor characteristics and metabolic pathways of higher alcohols as well as the application of mutagenesis breeding techniques in the regulation of higher alcohol metabolism in S. cerevisiae. In particular, we review the application of metabolic engineering technology in genetic modification of amino transferase, α-keto acid metabolism, acetate metabolism and carbon-nitrogen metabolism. Moreover, key challenges and future perspectives of realizing optimization of higher alcohols metabolism are discussed. This review is intended to provide a comprehensive understanding of metabolic regulation system of higher alcohols in S. cerevisiae and to provide insights into the rational development of the excellent industrial S. cerevisiae strains producing higher alcohols.


Subject(s)
Alcoholic Beverages , Alcohols/analysis , Fermentation , Saccharomyces cerevisiae/metabolism , Saccharomyces cerevisiae Proteins/metabolism
2.
São Paulo; s.n; 2010. 145 p. ilus, tab, graf.
Thesis in Portuguese | LILACS | ID: lil-595091

ABSTRACT

A aplicabilidade do processo de produção de microrganismos fotossintetizantes depende da obtenção de altas concentrações de biomassa e para isso seria interessante o emprego de fotobiorreatores tubulares. Eles permitem redução da área de cultivo e menor perda de CO2 e nitrogênio amoniacal por volatilização. Em uma primeira etapa deste trabalho, Arthrospira platensis foi cultivada por processo contínuo, avaliando-se diferentes valores de vazão específica de alimentação (D = 0,2 a 1,0 dia-1) e diferentes intensidades luminosas (I = 60 e 120 µmol fótons.m-2.s-1). Verificou-se que 120 µmol fótons.m-2.s-1 associada a D igual a 0,2 dia-1 resultou em maior valor de concentração celular em regime permanente (XP = 2446 ± 74 mg.L-1.d-1), mas o mesmo I associado a maior valor de D (0,6 dia-1) levou ao melhor valor de produtividade em células (PX = 938,73 mg.L-1.d-1). Foi possível a obtenção do regime permanente em quase todos os ensaios, o que indica que o cultivo contínuo de A. platensis em fotobiorreator tubular, usando uréia como fonte de nitrogênio, pode levar a resultados satisfatórios. Considerando a preocupação em relação à substituição de combustíveis fósseis por biocombustíveis, é iminente o crescente aumento da produção de etanol ainda nos próximos anos, e esse trabalho propõe o uso do CO2 liberado pela fermentação alcoólica na produção de microrganismos fotossintetizantes como A. platensis. Para isso, em uma segunda etapa, A. platensis foi cultivada por processo contínuo, com I igual a 120 µmol fótons.m-2.s-1, empregando uréia e CO2 proveniente de fermentação alcoólica para manutenção de pH e reposição da fonte de carbono. O uso desse CO2, sem tratamento prévio, associado a D igual a 0,6 dia-1 e concentração de uréia de 3,2 mM no meio de alimentação, permitiu a obtenção de PX igual a 839 ± 25 mg.L-1.d-1, o que está próximo de 938 ± 30mg.L-1.d-1, obtido com CO2 puro de cilindro. Estes resultados mostram que o uso de CO2 de fermentação alcoólica, associado a...


Appropriately designed tubular photobioreactors seem to be suitable for photosynthetic biomass production. It can reduce the cultivation area and provide lower loss of CO2 and ammoniacal nitrogen by volatilization. In a first step of this study, Arthrospira platensis was cultivated by continuous process, testing different values of dilution rate (D = 0.2 to 1.0 d-1) and light intensities (I = 60 and 120 µmol photons.m-2.s-1). The results of these runs showed that the maximum steady-state cell concentration (XS = 2446 ± 74 mg.L-1.d-1) was achieved at 120 µmol photons.m-2.s-1 and D of 0.2 d-1, but the same light intensity associated to higher dilution rate (0.6 d-1) provided the highest cell productivity (PX = 938 ± 30 mg.L-1.d-1), a value appreciably higher than that reported in other studies. Besides, steady-state conditions were achieved in most of the runs indicating that A. platensis continuous cultivation in the tubular photobioreactor, using urea as nitrogen source, can be performed effectively, thus appearing an interesting alternative for the large scale fixation of carbon dioxide to mitigate the green house effect. Taking into account the concern about the substitution of fossil fuel with biofuels, its evident that the ethanol production is going to increase even more in the next years, and this study propose the use of the CO2 released by the alcoholic fermentation for the production of photosynthetic microorganism such as A. platensis. For this purpose, in a second step, cultivations of A. platensis were carried out with 120 µmol photons.m-2.s-1 by continuous process, using urea and CO2 from Alcoholic fermentation for pH maintenance and carbon source replacement. The use of this CO2, without any treatment, associated with a D of 0.6 d-1 and feed urea concentration of 3.2 mM provide us a PX of 839 ± 25 mg.L-1.d-1, which is slightly lower than 938 ±30 mg.L-1.d-1, obtained with pure CO2 from cylinder. Our results showed that the use of CO2 from...


Subject(s)
Alcohols/analysis , Carbon Dioxide/chemistry , Fermentation , Bioreactors/statistics & numerical data , Spirulina/growth & development , Urea/chemical synthesis , Analysis of Variance , Biomass , Microbial Viability , Culture Media, Conditioned/chemistry
3.
Acta cient. venez ; 56(2): 54-59, 2005. graf
Article in Spanish | LILACS | ID: lil-537185

ABSTRACT

El comportamiento de fases en un sistema surfactante-agua-aceite se afecta por las llamadas variables de formulación, por ejemplo, por la naturaleza de los componentes o su ambiente fisicoquímico. Una de estas variables es la presencia del tipo y concentración de alcohol en el sistema. Para estudiar este efecto se realizaron barridos de formulación variando el número de óxido de etileno (EON) del sistema, por medio de la mezcla de un surfactante lipofílico con otro hidrofílico con el fin de hallar el sistema de máxima solubilidad (Winsor III óptimo) e incorporar en este sistema los alcoholes a diferentes concentraciones para observar el cambio de transición. El reparto se determinó por cromatografía líquida de alta resolución (HPLC). La adición de alcoholes lineales lipofílicos a estos sistemas proporciona mayor polaridad a la fase oleica y por ende mayor fraccionamiento hacia la misma. Se encontró que si la cadena alquílica del co-surfactante está por encima de un número de átomos de carbono promedio del alcohol (ACAN, acrónimo del inglés “alcohol carbon atom number”) igual a 4,5 el 50 por ciento del fraccionamiento no se ve afectado por el incremento de la concentración ni por el tipo de alcohol lipofílico.


Phase behavior in surfactant-water-oil systems is affected by the so-called formulation variables, for example, thenature of the components or their physiochemical environment. One of these variables is the presence of the type and concentration of the alcohol in the systems. The formulation scan varying the ethylene oxide number (EON) of the system were carried out, by means of the mixture of a lypophilic surfactant with another hydrophylic with the purpose of finding the maximum solubility system (Winsor III optimum) and to incorporate in this system the different alcohols with different concentrations to observe the transition change. The partititon coefficient was determined by high performance liquid cromatografic (HPLC). The addition of lineal lipophilics alcohols to these systems provides more polarity to the oil phase in consequence more fractionation towards it same one. It was found that if the alkyl chain of the co-surfactant is above an ACAN (alcohol atom carbon number) equal to 4,5 the 50 percent of fractionation is not affected by the increment of the concentration neither for the type of alcohol.


Subject(s)
Oils/analysis , Oils/chemistry , Surface-Active Agents/analysis , Surface-Active Agents/chemistry , Alcohols/analysis , Alcohols/adverse effects , Alcohols/chemistry , Chemistry
4.
Acta cient. venez ; 37(3): 318-24, 1986. ilus, tab
Article in Spanish | LILACS | ID: lil-44492

ABSTRACT

Se presenta una tecnología para la elaboración de cachirí (cachirí), bebida fermentada de yuca (Manihot esculenta Crantz) tradicionalmente consumida por algunas comunidades indígenas de Venezuela,Suriname y Guyana. En la tecnología propuesta se usó yuca fresca o harina de yuca como materia prima y el proceso comprendió tres etapas: 1) licuefacción, en la cual se utilizó alfa-amilasa y fue efectuada a 85-C y pH 6,0;2 sacarificación en la cual se empleó amiloglucosidasa y fue llevado a cabo a 60-C, pH 4,5; y 3) fermentación a 30-C y pH 4,5 empleando una levadura del género Saccharomyces. El mostro fermentado se clarificó, embotelló y pasteurizó. Esta bebida resultó ser un líquido de color ambar; de baja acidez (0,289g/100ml); con un nivel de etanol en el rango de 8,86 al 13,8% v/v y azúcares totales de 2.12% respectivamente. Las concentraciones de acetato de etilo, alcohol propílico, butílico y amílico, etc., fueron muy similares a los encontrados frecuentemente en vinos tradicionales


Subject(s)
Alcoholic Beverages , Alcohols/analysis , Fermentation , Indians, South American , Manihot , Plant Extracts
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