Papers by Volkmar Passoth
Biotechnology for biofuels and bioproducts, Mar 10, 2023
To show the peculiarities of regulation of fermentation and respiration in the respiratory yeast ... more To show the peculiarities of regulation of fermentation and respiration in the respiratory yeast P. stipitis, compared with S. cerevisiae.
Springer eBooks, 2003
To show the occurrence of cyanide-insensitive respiration in Pichia stipitis and the difference t... more To show the occurrence of cyanide-insensitive respiration in Pichia stipitis and the difference to other yeasts
Chapter 36 PROTOCOL Examination of Xylose Fermentation in Pichia stipitis by Means of the Sensoma... more Chapter 36 PROTOCOL Examination of Xylose Fermentation in Pichia stipitis by Means of the Sensomat System SANDRA FLUTHGRAF, ASTRID KIRCHHOFF, JAKOB DEBYE, VOLKMAR PASSOTH, and ULRICH KLINNER Aim To observe xylose fermentation of Pichia stipitis ...
Springer eBooks, 2003
To show the application of the yEGFP gene as a reporter of promoter activities of hypoxia-induced... more To show the application of the yEGFP gene as a reporter of promoter activities of hypoxia-induced genes in Pichia stipitis.
Bioresource Technology, 2000
... When the non-volatile fraction, obtained by roto-evaporation down to 10% (v/v) of the origina... more ... When the non-volatile fraction, obtained by roto-evaporation down to 10% (v/v) of the original volume, was diluted five times to obtain twice the concentration of non-volatile compounds in the original hydrolysate, the ethanol yield and productivity decreased to 46% and 36 ...
Current Microbiology, Oct 1, 1996
Microbial Cell Factories, Feb 3, 2020
Background: A possible future shortage of feed protein will force mankind to explore alternative ... more Background: A possible future shortage of feed protein will force mankind to explore alternative protein sources that can replace conventional soymeal or fishmeal. Several large industrial organic side-streams could potentially be upgraded to feed protein using a fermentation process to generate single cell protein. Yeast is the most widely accepted microorganism for production of single cell protein, because of its superior nutritional quality and acceptability among consumers. Here, we have assessed the growth of four different yeasts, Cyberlindnera jadinii, Wickerhamomyces anomalus, Blastobotrys adeninivorans and Thermosacc ® Dry (Saccharomyces cerevisiae), on media composed of enzymatically saccharified sulfite-pulped spruce wood and hydrolysates of by-products from chicken, and we have characterized the resulting yeast biomass. Results: Generally, the yeast grew very well on the spruce-and chicken-based medium, with typical yields amounting to 0.4-0.5 g of cell dry weight and 0.2-0.3 g of protein per g of sugar. B. adeninivorans stood out as the most versatile yeast in terms of nutrient consumption and in this case yields were as high as 0.9 g cells and 0.5 g protein per g of sugar. The next best performing yeast in terms of yield was W. anomalus with up to 0.6 g cells and 0.3 g protein per g sugar. Comparative compositional analyses of the yeasts revealed favorable amino acid profiles that were similar to the profiles of soymeal, and even more so, fish meal, especially for essential amino acids. Conclusions: The efficient conversion of industrial biomass streams to yeast biomass demonstrated in this study opens new avenues towards better valorization of these streams and development of sustainable feed ingredients. Furthermore, we conclude that production of W. anomalus or B. adeninivorans on this promising renewable medium may be potentially more efficient than production of the well-known feed ingredient C. jadinii. Further research should focus on medium optimization, development of semi-continuous and continues fermentation protocols and exploration of downstream processing methods that are beneficial for the nutritional values of the yeast for animal feed.
Antonie Van Leeuwenhoek International Journal of General and Molecular Microbiology, Oct 7, 2010
The first International Pichia anomala Symposium provided a survey of past, recent and ongoing re... more The first International Pichia anomala Symposium provided a survey of past, recent and ongoing research on this yeast. The research community working with this yeast has focussed on several areas. Based on molecular data, a revision of the taxonomy is required: the name P. anomala is no longer applicable, as the genus Pichia is polyphyletic. The current debate centres on whether the yeast should be designated as Wickerhamomyces anomalus or if the previous name, Hansenula anomala, should be reinstated. The anti-microbial activities of this yeast received considerable attention during the symposium. H. anomala has been extensively studied as a biopreservation agent in many different postharvest systems. Several mechanisms account for its anti-microbial activities, including the production of killer proteins and toxic volatile metabolites. Antiidiotypic antibodies generating an ''internal image'' of a killer protein have been found to possess therapeutic activity against a broad range of microorganisms. A great diversity of H. anomala strains was reported at the symposium. Strains have been isolated from several food and feed systems and even from the intestine and reproductive organs of a malaria vector (Anopheles stephensi). Feed and food supplemented with certain H. anomala strains show an improved quality due, for example, to the addition of advantageous proteins and phytase activity. However, a number of apparent opportunistic pathogenic strains have also been isolated. Strain differentiation, especially the recognition of potentially pathogenic isolates, is an important challenge for the future commercialisation of this yeast. Future industrial and agricultural application of this yeast also raises questions of the economics of large-scale production, its survival during storage (formulation) and of safety regulations, all of which require further investigation.
Springer eBooks, Dec 13, 2011
Biopreservation of moist animal feed provides an alternative to conventional conservation methods... more Biopreservation of moist animal feed provides an alternative to conventional conservation methods and is often beside of saving energy and antimicrobial chemicals a way to improve feed quality. In regions with temperate climate drying of cereal grains can require approximately 60% of the total energy input during plant husbandry. In tropical regions, drying can be incomplete due to high air humidity and improper handling of the material, resulting in a risk for contamination with mycotoxine forming moulds or pathogenic microorganisms. Microbial enzyme activities on feed and activation of intrinsic enzymes in plant material stored wet, increase the bioavalability of minerals and nutrients. For instance phytases can decrease the phytate content. Phytate is the main phosphate storage molecule in plants. It is only partially degraded in non-ruminants, resulting in phosphate release and eutrophication of water environments. Phytate is also an antinutrient, binding minerals and proteins and its degradation will improve the bioavailability of those substances. Biopreservation biomass can also be a locally produced protein source, which can replace soya. Soya production is frequently associated with negative environmental and socioeconomic consequences, and its worldwide trading requires energy for transport and handling. Translocation of nutrients between countries also precludes nutrient recirculation on arable land. Biopreservation often relies on spontaneous microbial developments, thus storage stability, feed hygiene, palatability and nutritional value may vary depending on the microbial composition. Microbial populations in feed are often monitored by traditional plate counting methods, but species identification of isolates demonstrated substantial changes in microbial populations even when plate counting indicated a stable flora. From economical, environmental and animal welfare perspectives it is of great interest to obtain a stable and predictable microbial population in the feed, which can be achieved by developing starter cultures.
Springer eBooks, 2017
Liquid biofuels have great potential to replace fossil transportation fuels. Bioethanol, the curr... more Liquid biofuels have great potential to replace fossil transportation fuels. Bioethanol, the current major biofuel, is mainly produced using the yeast Saccharomyces cerevisiae. However, present biofuels are largely generated from first generation, i.e. food grade, raw materials. Second generation, lignocellulosic biomass represents an abundant and cheap feedstock for bioethanol production; however, sugars present in cellulose and hemicellulose are difficult to access and not all of these sugars can be assimilated by S. cerevisiae. Other yeast species have been explored to ferment hemicellulose sugars such as xylose or to be specifically competitive in ethanol production. There are still attempts to introduce those species in industrial processes. The major approach has been to express heterologous genes enabling xylose assimilation in S. cerevisiae. Recently, by metabolic and evolutionary engineering in industrial isolates, S. cerevisiae strains applicable for industrial ethanol production from lignocellulose have been constructed. Apart from bioethanol, yeasts have been manipulated to produce butanol. Production of biodiesel and other advanced biofuels by oleaginous yeasts or engineered S. cerevisiae from lignocellulose has been proposed. Yeasts can also be used in side processes of biofuel production, such as preservation and pretreatment of biomass, or co-conversion of biomass to high value products.
Fems Yeast Research, May 8, 2015
This review summarizes the latest discoveries in the evolution of Dekkera bruxellensis, the physi... more This review summarizes the latest discoveries in the evolution of Dekkera bruxellensis, the physiology and metabolism of D. bruxellensis, its activity during wine fermentation and biotechnological potential in bioethanol industry.
Journal of Fungi, Mar 22, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Yeast, Jan 13, 2011
Scheffersomyces stipitis PJH was mutagenized by random integrative mutagenesis and the integrants... more Scheffersomyces stipitis PJH was mutagenized by random integrative mutagenesis and the integrants were screened for lacking the ability to grow with glutamate as sole carbon source. One of the two isolated mutants was damaged in the COX5 gene, which encodes a subunit of the cytochrome c oxidase. BLAST searches in the genome of Sc. stipitis revealed that only one singular COX5 gene exists in Sc. stipitis, in contrast to Saccharomyces cerevisiae, where two homologous genes are present. Mutant cells had lost the ability to grow with the amino acids glutamate, proline or aspartate and other non-fermentable carbon sources, such as acetic acid and ethanol, as sole carbon sources. Biomass formation of the mutant cells in medium containing glucose or xylose as carbon source was lower compared with the wild-type cells. However, yields and specific ethanol formation of the mutant were much higher, especially under conditions of higher aeration. The mutant cells lacked both cytochrome c oxidase activity and cyanide-sensitive respiration, whereas ADH and PDC activities were distinctly enhanced. SHAM-sensitive respiration was obviously essential for the fermentative metabolism, because SHAM completely abolished growth of the mutant cells with both glucose or xylose as carbon source.
Applied and Environmental Microbiology, Oct 21, 2011
Eleven of 13 Enterobacteriaceae species tested grew in moist stored wheat, highlighting a potenti... more Eleven of 13 Enterobacteriaceae species tested grew in moist stored wheat, highlighting a potential risk of this energy-saving airtight storage method. When Hansenula anomala was coinoculated, all Enterobacteriaceae species were significantly inhibited after 2 months of storage, six of them to below the detection limit.
Yeast, Mar 1, 2011
Scheffersomyces stipitis and the closely related yeast Candida shehatae assimilated the L-amino a... more Scheffersomyces stipitis and the closely related yeast Candida shehatae assimilated the L-amino acids glutamate, aspartate and proline as both carbon and nitrogen sole sources. We also found this rarely investigated ability in ascomycetous species such as Candida glabrata, C. reukaufii, C. utilis, Debaryomyces hansenii, Kluyveromyces lactis, K. marxianus, Candida albicans, L. elongisporus, Meyerozyma guilliermondii, C. maltosa, Pichia capsulata and Yarrowia lipolytica and in basidiomycetous species such as Rhodotorula rubra and Trichosporon beigelii. Glutamate was a very efficient carbon source for Sc. stipitis, which enabled a high biomass yield/mole, although the growth rate was lower when compared to growth on glucose medium. The cells secreted waste ammonium during growth on glutamate alone. In Sc. stipitis cultures grown in glucose medium containing glutamate as the nitrogen source the biomass yield was maximal, and ethanol concentration and specific ethanol formation rate were significantly higher than in glucose medium containing ammonium as the nitrogen source. Mainly C-assimilation of glutamate but also N-assimilation in glucose-containing medium correlated with enhanced activity of the NAD-dependent glutamate dehydrogenase 2 (GDH2). A gdh2 disruptant was unable to utilize glutamate as either a carbon or a nitrogen source; moreover, this disruptant was also unable to utilize aspartate as a carbon source. The mutation was complemented by retransformation of the GDH2 ORF into the gdh2 strain. The results show that Gdh2p plays a dual role in Sc. stipitis as both C-and N-catabolic enzyme, which indicates its role as an interface between the carbon and nitrogen metabolism of this yeast.
Journal of Applied Microbiology, 2010
Wet wheat distillers' grain is a co-product obtained from ethanol production, which is used in th... more Wet wheat distillers' grain is a co-product obtained from ethanol production, which is used in the animal feed industry. The use of such co-products to produce liquid feed avoids disposal issues and can decrease costs and the environmental burden of organic material (Scholten and Verdoes 1997; Brooks et al. 2001). Over the last decade there has been an increased usage of fermented wet feed for pigs world wide (Scholten et al. 1999; Canibe and Jensen 2003). During fermentation, microorganisms produce organic acids such as lactic and acetic acid, which reduce the pH of the feed to c. 3AE5-4AE5. Low pH and high concentrations of lactic and acetic acids in liquidfermented feed can prevent proliferation of Enterobacteriaceae along the animal gastrointestinal tract (
Research Square (Research Square), Dec 9, 2022
Background Lipid formation from glycerol was previously found to be activated in Rhodotorula toru... more Background Lipid formation from glycerol was previously found to be activated in Rhodotorula toruloides when the yeast was cultivated in a mixture of crude glycerol (CG) and hemicellulose hydrolysate (CGHH) compared to CG as the only carbon source. RNA samples from R. toruloides CBS14 cell cultures grown on either CG or CGHH were collected at different time points of cultivation, and a differential gene expression analysis was performed between cells grown at a similar physiological situation. Results We observed enhanced transcription of genes involved in oxidative phosphorylation and enzymes localized in mitochondria in CGHH compared to CG. Genes involved in protein turnover, including those encoding ribosomal proteins, translation elongation factors, and genes involved in building the proteasome also showed an enhanced transcription in CGHH compared to CG. At 10 h cultivation, another group of activated genes in CGHH was involved in β-oxidation, handling oxidative stress and degradation of xylose and aromatic compounds. Potential bypasses of the standard GUT1 and GUT2glycerol assimilation pathway were also expressed and upregulated in CGHH 10 h. When the additional carbon sources from HH were completely consumed, at CGHH 36 h, their transcription decreased and NAD +-dependent glycerol-3-phosphate dehydrogenase was upregulated compared to CG 60 h, generating NADH instead of NADPH with glycerol catabolism. TPI1 was upregulated in CGHH compared to cells grown on CG in all physiological situations, potentially channeling the DHAP formed through glycerol catabolism into glycolysis. The highest number of upregulated genes encoding glycolytic enzymes was found after 36 h in CGHH, when all additional carbon sources were already consumed. Conclusions We suspect that the physiological reason for the activation of metabolism, which was the basis for the accelerated glycerol assimilation and faster lipid production, was primarily the activation of enzymes that provide energy.
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Papers by Volkmar Passoth