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8. Proline catabolism is a key factor facilitating Candida albicans pathogenicity

Author

Silao, Fitz Gerald S., primary, Jiang, Tong, additional, Bereczky-Veress, Biborka, additional, Kühbacher, Andreas, additional, Ryman, Kicki, additional, Uwamohoro, Nathalie, additional, Jenull, Sabrina, additional, Nogueira, Filomena, additional, Ward, Meliza, additional, Lion, Thomas, additional, Urban, Constantin F., additional, Rupp, Steffen, additional, Kuchler, Karl, additional, Chen, Changbin, additional, Peuckert, Christiane, additional, and Ljungdahl, Per O., additional

Published
2023
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15. Proline catabolism is a key factor facilitating Candida albicans pathogenicity

Author

Silao, Fitz Gerald S., Jiang, Tong, Bereczky-Veress, Biborka, Kühbacher, Andreas, Ryman, Kicki, Uwamahoro, Nathalie, Jenull, Sabrina, Nogueira, Filomena, Ward, Meliza, Lion, Thomas, Urban, Constantin F., Rupp, Steffen, Kuchler, Karl, Chen, Changbin, Peuckert, Christiane, Ljungdahl, Per O., Silao, Fitz Gerald S., Jiang, Tong, Bereczky-Veress, Biborka, Kühbacher, Andreas, Ryman, Kicki, Uwamahoro, Nathalie, Jenull, Sabrina, Nogueira, Filomena, Ward, Meliza, Lion, Thomas, Urban, Constantin F., Rupp, Steffen, Kuchler, Karl, Chen, Changbin, Peuckert, Christiane, and Ljungdahl, Per O.

Abstract

Candida albicans, the primary etiology of human mycoses, is well-adapted to catabolize proline to obtain energy to initiate morphological switching (yeast to hyphal) and for growth. We report that put1-/- and put2-/- strains, carrying defective Proline UTilization genes, display remarkable proline sensitivity with put2-/- mutants being hypersensitive due to the accumulation of the toxic intermediate pyrroline-5-carboxylate (P5C), which inhibits mitochondrial respiration. The put1-/- and put2-/- mutations attenuate virulence in Drosophila and murine candidemia models and decrease survival in human neutrophils and whole blood. Using intravital 2-photon microscopy and label-free non-linear imaging, we visualized the initial stages of C. albicans cells infecting a kidney in real-time, directly deep in the tissue of a living mouse, and observed morphological switching of wildtype but not of put2-/- cells. Multiple members of the Candida species complex, including C. auris, are capable of using proline as a sole energy source. Our results indicate that a tailored proline metabolic network tuned to the mammalian host environment is a key feature of opportunistic fungal pathogens.

Published
2023
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18. Proline catabolism is key to facilitatingCandida albicanspathogenicity

Author

Silao, Fitz Gerald S., primary, Jiang, Tong, additional, Bereczky-Veress, Biborka, additional, Kühbacher, Andreas, additional, Ryman, Kicki, additional, Uwamohoro, Nathalie, additional, Jenull, Sabrina, additional, Nogueira, Filomena, additional, Ward, Meliza, additional, Lion, Thomas, additional, Urban, Constantin F., additional, Rupp, Steffen, additional, Kuchler, Karl, additional, Chen, Changbin, additional, Peuckert, Christiane, additional, and Ljungdahl, Per O., additional

Published
2023
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20. New Bioproduction Systems: From Molecular Circuits to Novel Reactor Concepts in Cell-Free Biotechnology

Author

Rupp, Steffen, Scheper, T., Series editor, Belkin, Shimshon, Series editor, Doran, Pauline M, Series editor, Endo, Isao, Series editor, Gu, Man Bock, Series editor, Hu, Wei Shou, Series editor, Mattiasson, Bo, Series editor, Nielsen, Jens, Series editor, Stephanopoulos, Gregory N., Series editor, Ulber, Roland, Series editor, Zeng, An-Ping, Series editor, Zhong, Jian-Jiang, Series editor, and Zhou, Weichang, Series editor

Published
2013
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22. Techno-Economic Analysis as a Driver for Optimisation of Cellobiose Lipid Fermentation and Purification

Author

Oraby, Amira, Rupp, Steffen, Zibek, Susanne, and Publica

Subjects
Histology, biosurfactant (BS), cellobiose lipids (CL), Biomedical Engineering, techno-economic analysis (TEA), Bioengineering, fermentation, Biotechnology, process optimisation
Abstract

Cellobiose lipids (CL) are glycolipids synthesized by Ustilaginaceae species with potential application as detergents or in cosmetics. This study identified process optimisation potential for CL fermentation based on process modelling and techno-economic analysis. Using a stoichiometric equation based on laboratory data, we calculated the maximum possible CL yield YP/S of 0.45 gCL·gglucose-1 at the biomass yield of 0.10 gBiomass·gglucose-1 with an Ustilago maydis strain. Due to substrate inhibition that may occur at high glucose concentrations, a fed-batch process to increase biomass and CL concentrations was considered in our model. Simulation of different process scenarios showed that the choice of aeration units with high oxygen transfer rates and adaptation of power input to oxygen uptake can significantly decrease electricity consumption. We further assessed scenarios with different fermentation media and CL purification methods, suggesting additional process optimisation potential. Here the omission of vitamins from the fermentation medium proved to be a possible mean to enhance process economy, without compromising CL productivity.

Published
2022

25. Optimization and Kinetic Modeling of a Fed-Batch Fermentation for Mannosylerythritol Lipids (MEL) Production with Moesziomyces aphidis

Author

Beck, Alexander, Vogt, Franziska, Hägele, Lorena, Rupp, Steffen, Zibek, Susanne, and Publica

Subjects
bioreactor, biosurfactants, process engineering, mannosylerythritol lipids, kinetic modeling, ustilaginaceae
Abstract

Mannosylerythritol lipids are glycolipid biosurfactants with many interesting properties. Despite the general interest in those molecules and the need for a robust process, studies on their production in bioreactors are still scarce. In the current study, the fermentative production of MEL in a bioreactor with Moesziomyces aphidis was performed using a defined mineral salt medium. Several kinetic process parameters like substrate consumption rates and product formation rates were evaluated and subsequently enhanced by increasing the biomass concentration through an exponential fed-batch strategy. The fed-batch approaches resulted in two to three fold increased dry biomass concentrations of 10.9-15.5 g/L at the end of the growth phase, compared with 4.2 g/L in the batch process. Consequently, MEL formation rates were increased from 0.1 g/Lh up to around 0.4 g/Lh during the MEL production phase. Thus, a maximum concentration of up to 50.5 g/L MEL was obtained when oil was added in excess, but high concentrations of residual fatty acids were also present in the broth. By adjusting the oil feeding to biomass-specific hydrolysis and MEL production rates, a slightly lower MEL concentration of 34.3 g/L was obtained after 170 h, but at the same time a very pure crude lipid extract with more than 90% MEL and a much lower concentration of remaining fatty acids. With rapeseed oil as substrate, the ideal oil-to-biomass ratio for full substrate conversion was found to be around 10 goil/gbiomass. In addition, off-gas analysis and pH trends could be used to assess biomass growth and MEL production. Finally, kinetic models were developed and compared to the experimental data, allowing for a detailed prediction of the process behavior in future experiments.

Published
2022

29. Liposomal siRNA Formulations for the Treatment of Herpes Simplex Virus-1: In Vitro Characterization of Physicochemical Properties and Activity, and In Vivo Biodistribution and Toxicity Studies

Author

Jbara-Agbaria, Doaa, primary, Blondzik, Saskia, additional, Burger-Kentischer, Anke, additional, Agbaria, Majd, additional, Nordling-David, Mirjam M., additional, Giterman, Anna, additional, Aizik, Gil, additional, Rupp, Steffen, additional, and Golomb, Gershon, additional

Published
2022
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41. PHR1, a pH-regulated gene of Candida albicans encoding a glucan-remodelling enzyme, is required for adhesion and invasion

Author

Calderon, Julia, Zavrel, Martin, Ragni, Enrico, Fonzi, William A., Rupp, Steffen, and Popolo, Laura

Subjects
Candida albicans -- Physiological aspects, Candida albicans -- Genetic aspects, Candida albicans -- Research, Host-parasite relationships -- Physiological aspects, Host-parasite relationships -- Genetic aspects, Transferases -- Physiological aspects, Transferases -- Genetic aspects, Transferases -- Research, Biological sciences
Abstract

The fungal cell wall plays a crucial role in host-pathogen interactions. Its formation is the result of the coordinated activity of several extracellutar enzymes, which assemble the constituents, and remodel and hydrolyse them in the extracellular space. Canclida albicans Phrl and Phr2 proteins belong to family GH72 of the [beta]-(1,)-glucanosyltransferases and play a crucial role in cell wall assembly. PHR1 and PHR2, homologues of Saccharomyces cerevisiae GAS1, are differently regulated by extracellular pH. PHR1 is expressed when ambient pH is 5.5 or higher, whereas PHR2 has the reverse expression pattern. Their deletion causes a pH-conditional defect in morphogenesis and virulence. In this work we explored whether PHR1 deletion affects the ability of C. albicans to adhere to and invade human epithelia. PHR1 null mutants exhibited a marked reduction in adhesion to both abiotic surfaces and epithelial cell monolayers. In addition, the mutant was unable to penetrate and invade reconstituted human epithelia. Transcription profiling of selected hyphal-specific and adhesin-encoding genes indicated that in the PHR1 null mutant, HWP1 and ECE1 transcript levels were similarly reduced in both adhesion and suspension conditions. These results, combined with microscopy analysis of the septum position, suggest that PHR1 is not required for the induction of hyphal development but plays a key role in the maintenance of hyphal growth. Thus, the [beta]-(1,)-glucan processing catalysed by Phrl p is of fundamental importance in the maintenance of the morphological state on which the adhesive and invasive properties of C. albicans greatly depend. DOI 10.1099/mic.0.038000-0

Published
2010

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