l-Arabinose triggers its own uptake via induction of the arabinose-specific Gal2p transporter in an industrial strain.

Bioethanol production processes with using lignocellulosic biomass as feedstock are challenged by the simultaneous utilization of pentose and hexose sugars from biomass hydrolysates. The pentose uptake into the cell represents a crucial role for the efficiency of the process. The focus of the here presented study was to understand the uptake and conversion of the pentose l-arabinose in and reveal its regulation by d-glucose and d-galactose.

The transporter AraT enables high-affinity, glucose-insensitive l-arabinose transport in .

Background: l-Arabinose occurs at economically relevant levels in lignocellulosic hydrolysates. Its low-affinity uptake via the Gal2 galactose transporter is inhibited by d-glucose. Especially at low concentrations of l-arabinose, uptake is an important rate-controlling step in the complete conversion of these feedstocks by engineered pentose-metabolizing strains.

Saccharomyces cerevisiae strains for second-generation ethanol production: from academic exploration to industrial implementation.

The recent start-up of several full-scale 'second generation' ethanol plants marks a major milestone in the development of Saccharomyces cerevisiae strains for fermentation of lignocellulosic hydrolysates of agricultural residues and energy crops. After a discussion of the challenges that these novel industrial contexts impose on yeast strains, this minireview describes key metabolic engineering strategies that have been developed to address these challenges. Additionally, it outlines how proof-of-concept studies, often developed in academic settings, can be used for the development of robust strain platforms that meet the requirements for industrial application.

Improved Xylose Metabolism by a Mutant of Saccharomyces cerevisiae.

Engineering for the utilization of pentose sugars is an important goal for the production of second-generation bioethanol and biochemicals. However, lacks specific pentose transporters, and in the presence of glucose, pentoses enter the cell inefficiently via endogenous hexose transporters (HXTs). By means of engineering, we have developed a quadruple hexokinase deletion mutant of that evolved into a strain that efficiently utilizes d-xylose in the presence of high d-glucose concentrations.

Improving pentose fermentation by preventing ubiquitination of hexose transporters in Saccharomyces cerevisiae.

Background: Engineering of the yeast Saccharomyces cerevisiae for improved utilization of pentose sugars is vital for cost-efficient cellulosic bioethanol production. Although endogenous hexose transporters (Hxt) can be engineered into specific pentose transporters, they remain subjected to glucose-regulated protein degradation. Therefore, in the absence of glucose or when the glucose is exhausted from the medium, some Hxt proteins with high xylose transport capacity are rapidly degraded and removed from the cytoplasmic membrane.

An engineered cryptic Hxt11 sugar transporter facilitates glucose-xylose co-consumption in Saccharomyces cerevisiae.

Background: The yeast Saccharomyces cerevisiae is unable to ferment pentose sugars like d-xylose. Through the introduction of the respective metabolic pathway, S. cerevisiae is able to ferment xylose but first utilizes d-glucose before the d-xylose can be transported and metabolized.

Engineering of an endogenous hexose transporter into a specific D-xylose transporter facilitates glucose-xylose co-consumption in Saccharomyces cerevisiae.

Background: Engineering of Saccharomyces cerevisiae for the simultaneous utilization of hexose and pentose sugars is vital for cost-efficient cellulosic bioethanol production. This yeast lacks specific pentose transporters and depends on endogenous hexose transporters for low affinity pentose uptake. Consequently, engineered xylose-fermenting yeast strains first utilize D-glucose before D-xylose can be transported and metabolized.

Searching for microbial protein over-expression in a complex matrix using automated high throughput MS-based proteomics tools.

In the discovery of new enzymes genomic and cDNA expression libraries containing thousands of differential clones are generated to obtain biodiversity. These libraries need to be screened for the activity of interest. Removing so-called empty and redundant clones significantly reduces the size of these expression libraries and therefore speeds up new enzyme discovery.

De novo sequencing, assembly and analysis of the genome of the laboratory strain Saccharomyces cerevisiae CEN.PK113-7D, a model for modern industrial biotechnology.

Saccharomyces cerevisiae CEN.PK 113-7D is widely used for metabolic engineering and systems biology research in industry and academia. We sequenced, assembled, annotated and analyzed its genome.

Degeneration of penicillin production in ethanol-limited chemostat cultivations of Penicillium chrysogenum: A systems biology approach.

Background: In microbial production of non-catabolic products such as antibiotics a loss of production capacity upon long-term cultivation (for example chemostat), a phenomenon called strain degeneration, is often observed. In this study a systems biology approach, monitoring changes from gene to produced flux, was used to study degeneration of penicillin production in a high producing Penicillium chrysogenum strain during prolonged ethanol-limited chemostat cultivations.

Results: During these cultivations, the biomass specific penicillin production rate decreased more than 10-fold in less than 22 generations.

Exploring and dissecting genome-wide gene expression responses of Penicillium chrysogenum to phenylacetic acid consumption and penicillinG production.

Background: Since the discovery of the antibacterial activity of penicillin by Fleming 80 years ago, improvements of penicillin titer were essentially achieved by classical strain improvement through mutagenesis and screening. The recent sequencing of Penicillium chrysogenum strain Wisconsin1255-54 and the availability of genomics tools such as DNA-microarray offer new perspective.

Results: In studies on beta-lactam production by P.

Comparison of outcomes in high-risk patients>70 years of age with aortic valvuloplasty and percutaneous coronary intervention versus aortic valvuloplasty alone.

The goal of this study was to compare outcomes of combined balloon aortic valvuloplasty (BAV) plus percutaneous coronary intervention (PCI) with BAV alone in a surgically high risk, older (>70 years) population with both aortic stenosis (AS) and coronary artery disease (CAD). The medical records, coronary angiograms, and procedural reports of 100 consecutive patients who underwent BAV and coronary angiography at our institution from July 2003 to November 2006 were reviewed. Seventeen patients (mean age 86.

Production of functionally active Penicillium chrysogenum isopenicillin N synthase in the yeast Hansenula polymorpha.

Background: beta-Lactams like penicillin and cephalosporin are among the oldest known antibiotics used against bacterial infections. Industrially, penicillin is produced by the filamentous fungus Penicillium chrysogenum. Our goal is to introduce the entire penicillin biosynthesis pathway into the methylotrophic yeast Hansenula polymorpha.

Feasibility of transcatheter intervention for severe aortic stenosis in patients >or=90 years of age: aortic valvuloplasty revisited.

Objectives: The goals of this study were to determine the feasibility, safety, and early outcomes of balloon aortic valvuloplasty (BAV) for severe aortic stenosis in a nonagenarian population.

Background: This very elderly population is expanding rapidly, has a high incidence of aortic stenosis, and uncommonly undergoes surgical aortic valve replacement. These patients may best be treated with a transcatheter approach due to comorbidities, surgical risk, and personal preference.