Category Archives: Advances in Biochemical Engineering/Biotechnology

Evaluation of New Thermostable Enzyme Mixtures

Mixtures of selected thermostable enzymes (Table 2) were first evaluated for their hydrolytic efficiency by measuring the FPU activities at different tem­peratures (Fig. 3). The temperature optima of the new thermostable mixtures in the FPU activity assay were 5-10 °C higher than those of the commercial enzyme mixtures when a relatively short reaction time (60 min) in this assay was […]

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Xylose Isomerase: Properties and Occurrence

Xylose isomerase (XI, D-xylose ketol isomerase, EC 5.3.1.5) catalyses the re­versible isomerisation of D-xylose to D-xylulose. This enzyme has been the subject of much applied research because it also catalyses the isomerisation of D-glucose and D-fructose. In this role of “glucose isomerase”, xylose iso — merase is applied on a huge scale for the production of high-fructose corn syrup and […]

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Proteomics

Proteomics is the quantitative study of all proteins expressed in a cell under defined conditions. Proteomics represents one of the more challeng­ing x-omes given that analytical methods enabling measurement of all pro­teins with the sensitivity, accuracy, and precision required have only recently been developed [62,72]. Rapid advances in protein analytical technologies, fueled by the addition of mass spectrometry (MS), liquid […]

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Impact of Process Steps on Enzyme Dosage and Cost

The amount and types of enzymes required for the saccharification of cel­lulose and hemicellulose are strongly dependent on the biomass being hy­drolyzed and the type and severity of pretreatment. Ultimately the selection of biomass feedstock will be based on local availability and economy of sup­ply. In the early stages of commercial development, feedstocks with the great­est potential for demonstrating economic […]

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Sugar Transport

The transport of pentose sugars in S. cerevisiae occurs through hexose trans­porters [80,81], albeit with an affinity one to two orders of magnitude lower than for hexose sugars [47,82]. Therefore, pentose transport was early con­sidered a rate-controlling step for ethanolic pentose fermentation [47]. Nev­ertheless, a metabolic control analysis study demonstrated that transport controlled xylose conversion only in strains with high […]

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Baker’s Yeast (5. cerevisiae) as a CBP Host

Despite the status of S. cerevisiae as a proven industrial microorganism, con­ferring the ability to rapidly convert pretreated cellulose to ethanol is a daunt­ing proposition. Apart from essential traits, such as high ethanol yield and productivity, industrial strains need to concurrently ferment both hexoses and pentoses under robust industrial conditions that require minimum nutri­ent requirements and high ethanol and inhibitor […]

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