Category Archives: Advances in Biochemical Engineering/Biotechnology

Improving Ethanolic Fermentation by Pentose-Utilizing S. cerevisiae

It soon became evident that the mere introduction ofpentose utilization path­ways in S. cerevisiae was not enough to render the recombinant strains traits for efficient ethanol fermentation [43] (strain RWB202, Tables 3 and 4), [47, 48,78,79] (strain TMB3001, Tables 1-3). A number of metabolic engin­eering strategies to enhance ethanolic xylose (and arabinose) fermentation in S. cerevisiae have been explored, the […]

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Other Biofuel Producing Nations

Other major biofuel producers include China, which has grown its bioethanol production sector rapidly since 2000 to become the third-largest single bioethanol producer after the USA. Total capacity from four plants in 2005 was about 1.3 billion L, but continued high prices for international oil has led the National Development and Reform Commission to announce that biofuel production will increase […]

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Random Methods

Random methods such as mutagenesis, adaptation, hybridization, and evo­lutionary engineering [130] have been employed to obtain improved xylose­utilizing [5,42,110,131] (strains TMB3400, C1, C5, BH42, RWB218, RWB202- AFX, H2490-4, Tables 1, 3, and 4) and arabinose-utilizing [71] S. cerevisiae strains. Some of the resultant strains have been analyzed in order to identify molecular traits related to the improved ethanolic fermentation of […]

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Limitations and Challenges

Because dependence on nutritional supplementation increases the process cost, the ideal biocatalyst should produce high amounts of ethanol in sim­ple mineral salts growth medium. While KO11 and LY01 both attained high ethanol yields and titers in rich media, these microbial biocatalysts perform poorly in minimal media. With nutritional supplementation, KO11 produced 45 g L-1 ethanol from 100 g L-1 glucose […]

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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 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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