RESUMEN
In this work, corn stover subjected to ammonia fiber expansion (AFEX™)1 pretreatment or alkaline pre-extraction followed by hydrogen peroxide post-treatment (AHP pretreatment) were compared for their enzymatic hydrolysis yields over a range of solids loadings, enzymes loadings, and enzyme combinations. Process techno-economic models were compared for cellulosic ethanol production for a biorefinery that handles 2000tons per day of corn stover employing a centralized biorefinery approach with AHP or a de-centralized AFEX pretreatment followed by biomass densification feeding a centralized biorefinery. A techno-economic analysis (TEA) of these scenarios shows that the AFEX process resulted in the highest capital investment but also has the lowest minimum ethanol selling price (MESP) at $2.09/gal, primarily due to good energy integration and an efficient ammonia recovery system. The economics of AHP could be made more competitive if oxidant loadings were reduced and the alkali and sugar losses were also decreased.
Asunto(s)
Biotecnología/métodos , Etanol/metabolismo , Zea mays/química , Amoníaco/química , Biomasa , Biotecnología/economía , Costos y Análisis de Costo , Enzimas/química , Enzimas/metabolismo , Etanol/economía , Peróxido de Hidrógeno/química , Hidrólisis , Monosacáridos/química , Brotes de la Planta/química , Brotes de la Planta/metabolismo , Hidróxido de Sodio/química , Zea mays/metabolismoRESUMEN
Although single-cell oil (SCO) has been studied for decades, lipid production from lignocellulosic biomass has received substantial attention only in recent years as biofuel research moves toward producing drop-in fuels. This review gives an overview of the feasibility and challenges that exist in realizing microbial lipid production from lignocellulosic biomass in a biorefinery. The aspects covered here include biorefinery technologies, the microbial oil market, oleaginous microbes, lipid accumulation metabolism, strain development, process configurations, lignocellulosic lipid production, technical hurdles, lipid recovery, and technoeconomics. The lignocellulosic SCO-based biorefinery will be feasible only if a combination of low- and high-value lipids are coproduced, while lignin and protein are upgraded to high-value products.
Asunto(s)
Bacterias/metabolismo , Biotecnología/métodos , Lignina/química , Lípidos/biosíntesis , Microalgas/metabolismo , Biocombustibles , Biomasa , Vías Biosintéticas , Lignina/metabolismo , Lípidos/química , Modelos BiológicosRESUMEN
Recovery and purification of organic acids produced in fermentation constitutes a significant fraction of total production cost. In this paper, the design and economic analysis of a process to recover succinic acid (SA) via dissolution and acidification of succinate salts in ethanol, followed by reactive distillation to form succinate esters, is presented. Process simulation was performed for a range of plant capacities (13-55 million kg/yr SA) and SA fermentation titers (50-100 kg/m(3)). Economics were evaluated for a recovery system installed within an existing fermentation facility producing succinate salts at a cost of $0.66/kg SA. For a SA processing capacity of 54.9 million kg/yr and a titer of 100 kg/m(3) SA, the model predicts a capital investment of $75 million and a net processing cost of $1.85 per kg SA. Required selling price of diethyl succinate for a 30% annual return on investment is $1.57 per kg.
Asunto(s)
Biotecnología/economía , Biotecnología/métodos , Fermentación , Ácido Succínico/economía , Ácido Succínico/metabolismo , Costos y Análisis de Costo , Destilación , Esterificación , Etanol/economía , Etanol/metabolismo , Succinatos/economía , Succinatos/metabolismoRESUMEN
La enfermedad periodontal presenta una etiología multifactorial donde están implicados varios factores de riesgo, entre ellos la interleuqina 1Beta, citoquina proinflamatoria asociada con reabsorción ósea y con el catabolismo de la matriz extracelular. Se han descrito polimorfismos genéticos en la interleuqina -1, entre ellos, la presencia del alelo 2 en la IL-1b+3953, asociada a pacientes no fumadores, 60 con enfermedad periodontal crónica moderada o severa y 60 pacientes sanos. Se realizaron evaluaciones clínicas para el grupo control; el grupo caso fue seleccionado radiográficamente. Para determinar el genotipo, se extrajo el DNA de muestras salivares, se utilizó el método de reacción en cadena de polimerasa (PCR), digestión de enzimas de restricción (RFLP) y electroforésis. Se encontró el alelo 2 para la IL-1â+3953 (genotipo homocigótico ½ + genotipo heterocigótico 2/2), en el 32.5 por ciento y no se observaron diferencias estadísticamente significativas entre casos y controles para la presencia del alelo 2 de la IL-1â+3953. (59 por ciento vs 41 por ciento). En este estudio no se encontró asociación entre el polimorfismo de la IL-1B+3953 y la presencia de enfermedad periodontal crónica severa. Se sugiere otros estudios donde se evalúen otros alelos para la interleuquina 1...