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There is considerable interest in exploiting the novel physical and biological properties of microbial exopolysaccharides in industry and medicine. For economic and scientific reasons, large scale production under carefully monitored and controlled conditions is required. Producing exopolysaccharides in industrial fermenters poses several complex bioengineering and microbiological challenges relating primarily to the very high viscosities of such culture media, which are often exacerbated by the producing organism''s morphology. What these problems are, and the strategies for dealing with them are discussed critically in this review, using pullulan, curdlan, xanthan, and fungal ββ-glucans as examples of industrially produced microbial exopolysaccharides. The role of fermenter configuration in their production is also examined. [ABSTRACT FROM AUTHOR]

We tested the hypothesis that endogenously produced hydrogen sulfide (H2S) can potentially contribute to the adrenergic stress response in rainbow trout by initiating catecholamine secretion from chromaffin cells. During acute hypoxia (water P02 = 35 mmHg), plasma H2S levels were significantly elevated concurrently with a rise in circulating catecholamine concentrations. Tissues enriched with chromaffin cells (posterior cardinal vein and anterior kidney) produced H2S in vitro when incubated with L-cysteine. In both tissues, the production of H2S was eliminated by adding the cystathionine β-synthase inhibitor, aminooxyacetate. Cystathionine β-synthase and cystathionine γ-lyase were cloned and sequenced and the results of real-time PCR demonstrated that with the exception of white muscle, mRNA for both enzymes was broadly distributed within the tissues that were examined. Electrical field stimulation of an in situ saline-perfused posterior cardinal vein preparation caused the appearance of H2S and catecholamines in the outfiowing perfusate. Perfusion with the cholinergic receptor agonist carbachol (1 X 10-6 M) or depolarizing levels of KCI (1 X 10-2 M) caused secretion of catecholamines without altering H2S output, suggesting that neuronal excitation is required for H2S release. Addition of H2S (at concentrations exceeding 5 X 10-7 M) to the perfusion fluid resulted in a marked stimulation of catecholamine secretion that was not observed when Ca2+-free perfusate was used. These data, together with the finding that H2S-induced catecholamine secretion was unaltered by the nicotinic receptor blocker hexamethonium, suggest that H2S is able to directly elicit catecholamine secretion via membrane depolarization followed by Ca2+-mediated exocytosis. [ABSTRACT FROM AUTHOR]

Although host proteases are often considered to have a negative impact upon heterologous protein production by filamentous fungi, relatively little is known about the pattern of their appearance in recombinant fungal bioprocesses. In the present study, we investigated extracellular proteases from a filamentous fungus, Aspergillus niger B1-D, genetically modified to secrete hen egg white lysozyme (HEWL). Our findings indicate that extracellular protease activity is only detected after the carbon source is completely utilised in batch cultures. The proteases are predominantly acid proteases and have optimal temperature for activity at around 45°C. Their activity could be partially inhibited by protease inhibitors, indicating the existence of at least four kinds of proteases in these culture fluids, aspartic-, serine-, cysteine-, and metallo-proteases. Oxygen enrichment does not have any noticeable effects on extracellular protease activity except that the onset of protease activity appears earlier in oxygen enrichment runs. Oxygen enrichment stimulates HEWL production substantially, and we propose that it is related to fungal morphology. Thermal stress imposed by raising process temperature (from 25 to 30 and 35°C) in early exponential phase, led to appearance of protease activity in the medium following the heat shock. Continued cultivation at high temperatures significantly reduced HEWL production, which was associated with increased activity of the extracellular proteases in these cultures. [ABSTRACT FROM AUTHOR]

The Pichia pastoris expression system is being used successfully for the production of various recombinant heterologous proteins. Recent developments with respect to the Pichia expression system have had an impact on not only the expression levels that can be achieved, but also the bioactivity of various heterologous proteins. We review here some of these recent developments, as well as strategies for reducing proteolytic degradation of the expressed recombinant protein at cultivation, cellular and protein levels. The problems associated with post-translational modifications performed on recombinant proteins by P. pastoris are discussed, including the effects on bioactivity and function of these proteins, and some engineering strategies for minimizing unwanted glycosylations. We pay particular attention to the importance of optimizing the physicochemical environment for efficient and maximal recombinant protein production in bioreactors and the role of process control in optimizing protein production is reviewed. Finally, future aspects of the use of the P. pastoris expression system are discussed with regard to the production of complex membrane proteins, such as G protein-coupled receptors, and the industrial and clinical importance of these proteins. Copyright © 2005 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

It has been known for many years that oxygen (O2) may have toxic effects on aerobically growing microorganisms, mainly due to the threat arising from reactive oxygen species (ROS). In submerged culture industrial fermentation processes, maintenance of adequate levels of O2 (usually measured as dissolved oxygen tension (DOT)) can often be critical to the success of the manufacturing process. In viscous cultures of filamentous cultures, actively respiring, supplying adequate levels of O2 to the cultures by conventional air sparging is difficult and various strategies have been adopted to improve or enhance O2 transfer. However, adoption of those strategies to maintain adequate levels of DOT, that is, to avoid O2 limitation, may expose the fungi to potential oxidative damage caused by enhanced flux through the respiratory system. In the past, there have been numerous studies investigating the effects of DOT on fungal bioprocesses. Generally, in these studies moderately enhanced levels of O2 supply resulted in improvement in growth, product formation and acceptable morphological changes, while the negative impact of higher levels of DOT on morphology and product synthesis were generally assumed to be a consequence of "oxidative stress." However, very little research has actually been focused on investigation of this implicit link, and the mechanisms by which such effects might be mediated within industrial fungal processes. To elucidate this neglected topic, this review first surveys the basic knowledge of the chemistry of ROS, defensive systems in fungi and the effects of DOT on fungal growth, metabolism and morphology. The physiological responses of fungal cells to oxidative stress imposed by artificial and endogenous stressors are then critically reviewed. It is clear that fungi have a range of methods available to minimize the negative impacts of elevated ROS, but also that development of the... [ABSTRACT FROM AUTHOR]

The application of Fourier Transform near infrared spectroscopy (FT-NIRS) to near real-time monitoring of polysaccharide and biomass concentration was investigated using a gellan-producing strain of Sphingomonas paucimobilis grown in a stirred tank reactor. Successful models for both biomass and gellan were constructed despite the physichochemical complexity of the viscous process fluid. Modelling of biomass proved more challenging than for gellan, partly because of the low range of biomass concentration but a model with a good correlation coefficient (0.94) was formulated based on second derivative spectra. The gellan model was highly satisfactory, with an excellent correlation coefficient (0.98), again based on second derivative spectra. No sample pre-treatment was required and all spectral scanning was carried out on whole broth. Additionally, both models should be robust in practice since both were formulated using low numbers of factors. Thus, the near real time simultaneous monitoring of gellan and biomass in this highly complex matrix using FT-NIRS potentially opens the way to greatly improved process control strategies. [ABSTRACT FROM AUTHOR]

Mid-infrared spectroscopy (MIRS) was used to simultaneously detect and predict concentrations of d-sorbitol and l-sorbose during a Gluconobacter suboxydans biotransformation. Quantitative models for both these compounds were developed for the entire time-course of the process and validated externally using samples not included in the original modelling exercise, giving standard errors of prediction of 3.29 and 3.3% for sorbitol and sorbose, respectively, and a correlation coefficient close to 1. [ABSTRACT FROM AUTHOR]

Near infrared spectroscopy (NIRS) was used to monitor an industrial bioprocess for the production of the antibiotic, tylosin, using a segmented modelling approach. Models were built over the entire time course of the fermentation from 0 to 150 h, and also in two distinct phases or segments of the bioprocess from 50 to 100 h (synthetic phase) and from 100 to 150 h (stationary phase). All models were validated externally and the performance of the full range and segmented models compared. The standard error of prediction (SEP) of the segmented models was less in both 50–100 h and 100–150 h and the correlation highest in the 50–100 h range. This would suggest that data segmentation is potentially a useful method of accommodating the impact of the pronounced matrix changes which occur in some bioprocesses in NIRS models for key analytes. While there are many reports on bioprocess monitoring using NIRS, there have been no previous studies on the use of segmented NIR models within a bioprocess as a means of accommodating matrix change. [ABSTRACT FROM AUTHOR]

The article cites a study which investigates the interactive effects of race, recidivism, and type of crime in incarcerated adult males on the Problem Solving Inventory and Minnesota Multiphasic Personality Inventory (MMPI) scales. The MMPI is an objective personality inventory that is used to assess abnormal behavior. Subjects were 52 volunteers selected from a pool of 61. Nine subjects were discarded from the sample because of missing data. Some of the significant results found in the analyses of these data are limited in their interpretability because the scale score means fall within the normal ranges of MMPI scores.

Inflammatory myofibroblastic tumor (IMT) is a tumor of unknown neoplastic potential that rarely arises in the genitourinary tract. We present the case of an otherwise healthy 16-year old boy with gross hematuria who underwent cystoscopy and transurethral resection of the bladder tumor without complication. Biopsy and immunohistochemistry were consistent with anaplastic lymphoma kinase-positive IMT. In addition to presenting this case of IMT, we review presentations, management and prognosis of bladder IMT. [ABSTRACT FROM AUTHOR]

The article reports that the scientists of SLAC National Accelerator Laboratory in Menlo Park, California, have successfully completed a free-electron laser (FEL) facility which can achieve lasing at a wavelength of 1.5 Å. Experts believe that this FEL, the first to operate in the hard X-ray regime, will open up vast new areas for scientific exploration in the field of light-source science. They state that this source will help in study of atomic and molecular science.

The article discusses on the free-electron lasers (FELs) operating at X-ray wavelengths to gather detailed information on how matter interacts and arranges itself at atomic and molecular scales. It states that the output from the FEL is around 108 brighter than current synchrotron sources. The information gathered by the X-ray FELs about molecules, atoms and their electronic states are more efficient than current synchrotron X-ray sources.