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BackgroundThe physiological characterization of microorganisms provides valuable information for bioprocess development. Chemostat cultivations are a powerful tool for this purpose, as they allow defined changes to one single parameter at a time, which is most commonly the growth rate. The subsequent establishment of a steady state then permits constant variables enabling the acquisition of reproducible data sets for comparing microbial performance under different conditions. We performed physiological characterizations of a 3-hydroxypropionic acid (3-HP) producing Saccharomyces cerevisiae strain in a miniaturized and parallelized chemostat cultivation system. The physiological conditions under investigation were various growth rates controlled by different nutrient limitations (C, N, P). Based on the cultivation parameters obtained subsequent fed-batch cultivations were designed.ResultsWe report technical advancements of a small-scale chemostat cultivation system and its applicability for reliable strain screening under different physiological conditions, i.e. varying dilution rates and different substrate limitations (C, N, P). Exploring the performance of an engineered 3-HP producing S. cerevisiae strain under carbon-limiting conditions revealed the highest 3-HP yields per substrate and biomass of 16.6 %C-mol and 0.43 g gCDW-1, respectively, at the lowest set dilution rate of 0.04 h-1. 3-HP production was further optimized by applying N- and P-limiting conditions, which resulted in a further increase in 3-HP yields revealing values of 21.1 %C-mol and 0.50 g gCDW-1 under phosphate-limiting conditions. The corresponding parameters favoring an increased 3-HP production, i.e. dilution rate as well as C- and P-limiting conditions, were transferred from the small-scale chemostat cultivation system to 1-L bench-top fermenters operating in fed-batch conditions, revealing 3-HP yields of 15.9 %C-mol and 0.45 g gCDW-1 under C-limiting, as well as 25.6 %C-mol and 0.50 g gCDW-1 under phosphate-limiting conditions.ConclusionsSmall-scale chemostat cultures are well suited for the physiological characterization of microorganisms, particularly for investigating the effect of changing cultivation parameters on microbial performance. In our study, optimal conditions for 3-HP production comprised (i) a low dilution rate of 0.04 h-1 under carbon-limiting conditions and (ii) the use of phosphate-limiting conditions. Similar 3-HP yields were achieved in chemostat and fed-batch cultures under both C- and P-limiting conditions proving the growth rate as robust parameter for process transfer and thus the small-scale chemostat system as powerful tool for process optimization.

Copyright of Journal der Deutschen Dermatologischen Gesellschaft is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Summary: Stevens‐Johnson syndrome and toxic epidermal necrolysis (SJS/TEN) are rare, predominantly drug‐induced, acute life‐threatening diseases of skin and mucosae. SJS and TEN are nowadays considered as variants of one disease entity with varying degrees of severity called epidermal necrolysis (EN). EN is associated with high morbidity and mortality and constitutes a major disease burden for affected patients. The guideline "Diagnosis and treatment of epidermal necrolysis (Stevens‐Johnson syndrome and toxic epidermal necrolysis)" was developed under systematic consideration of existing scientific literature and in a formal consensus process according to regulations issued by the Association of Scientific Medical Societies in Germany (AWMF) to establish an evidence‐based framework to support clinical decision‐making. The interdisciplinary guideline commission consisted of representatives from various specialist societies and of patient representatives. The guideline is aimed at specialists in the fields of dermatology, ophthalmology, plastic surgery, intensive care, and pediatrics in hospitals and offices, as well as other medical specialties involved in the diagnosis and treatment of EN. The guideline is also aimed at patients, their relatives, insurance funds, and policymakers. The second part is concerned with the topics of supportive therapy in the acute phase of EN and outpatient follow‐up treatment. [ABSTRACT FROM AUTHOR]

Copyright of Journal der Deutschen Dermatologischen Gesellschaft is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Summary: Stevens‐Johnson syndrome and toxic epidermal necrolysis (SJS/TEN) are rare, predominantly drug‐induced, acute, life‐threatening diseases of skin and mucosae. SJS and TEN are nowadays considered variants of one disease entity with varying degrees of severity called epidermal necrolysis (EN). EN is associated with high morbidity and mortality and constitutes a major disease burden for affected patients. The guideline "Diagnosis and treatment of epidermal necrolysis (Stevens‐Johnson syndrome and toxic epidermal necrolysis)" was developed under systematic consideration of existing scientific literature and in a formal consensus process according to regulations issued by the Association of Scientific Medical Societies in Germany (AWMF) to establish an evidence‐based framework to support clinical decision‐making. The interdisciplinary guideline commission consisted of representatives from various specialist societies and patient representatives. The guideline is aimed at specialists in the fields of dermatology, ophthalmology, plastic surgery, intensive care, and pediatrics in hospitals and offices, as well as other medical speciallved in the diagnosis and treatment of EN. The guideline is also aimed at patients, their relatives, insurance funds, and policymakers. This first part focuses on the diagnostic aspects, the initial management as well as the immunomodulating systemic therapy. [ABSTRACT FROM AUTHOR]

In physical foaming processes of thermoplastics, a liquid mixture consisting of a molten polymer with a dissolved blowing agent is extruded through a die or injected into a mold. The morphology of the foam matrix strongly depends on the mutual diffusion coefficient D11 of the liquid polymer-blowing agent mixture. For a better understanding of the underlying physical mechanisms during the foaming process and the development of corresponding models, accurate knowledge of D11 is needed. This work reports on the simultaneous measurement of D11 and the thermal diffusivity a of liquid mixtures consisting of polystyrene melts with dissolved nitrogen (N2) or carbon dioxide (CO2) at mass fractions wsolute up to 0.003 or 0.02 and temperatures T between (433 and 533) K using dynamic light scattering (DLS). The determined D11 range is between (1 and 4) × 109 m2⋅s−1 and are slightly larger for the mixtures containing N2 at a given T and wsolute. D11 could be determined with an average expanded relative uncertainty of 18%. Considering all investigated state points and the achieved experimental uncertainties, both D11 and a are independent on the amount of dissolved gas, despite relatively large mole fractions of the dissolved blowing agents xsolute of 0.997 and 0.93. [ABSTRACT FROM AUTHOR]