Background The gut fermentation syndrome (GFS), also known as the endogenous alcohol fermentation syndrome or auto brewery syndrome, is a rare and underdiagnosed medical condition where consumed... Show moreBackground The gut fermentation syndrome (GFS), also known as the endogenous alcohol fermentation syndrome or auto brewery syndrome, is a rare and underdiagnosed medical condition where consumed carbohydrates are converted to alcohol by the microbiota in the gastrointestinal or urinary tract. The symptoms of GFS can have severe impact on patients' wellbeing and can have social and legal consequences. Unfortunately, not much is reported about GFS. The aim of this systematic review was to assess the evidence for GFS, causal micro-organisms, diagnostics, and possible treatments.Methods A protocol was developed prior to initiation of the systematic review (PROSPERO 207182).We performed a literature search for clinical studies on 1 September 2020 using PubMed and Embase. We included all clinical studies, including case reports that described the GFS.Results In total, 17 case reports were included, consisting of 20 patients diagnosed with GFS. The species that caused the GFS included Klebsiella pneumoniae, Candida albicans, C. glabrata, Saccharomyces cerevisiae, C. intermedia, C. parapsilosis, and C. kefyr.Conclusions GFS is a rare but underdiagnosed disease in daily practice. The disease is mostly reported by Saccharomyces and Candida genera, and some cases were previously treated with antibiotics. Studies in Nonalcoholic Fatty Liver disease suggest a bacterial origin of endogenous alcohol-production, which might also be causal micro-organisms in GFS. Current treatments for GFS include antibiotics, antifungal medication, low carbohydrate diet, and probiotics. There might be a potential role of fecal microbiota transplant in the treatment of GFS. Show less
Wiersma, S.J.; Mooiman, C.; Giera, M.; Pronk, J.T. 2020
Biosynthesis of sterols, which are considered essential components of virtually all eukaryotic membranes, requires molecular oxygen. Anaerobic growth of the yeast Saccharomyces cerevisiae therefore... Show moreBiosynthesis of sterols, which are considered essential components of virtually all eukaryotic membranes, requires molecular oxygen. Anaerobic growth of the yeast Saccharomyces cerevisiae therefore strictly depends on sterol supplementation of synthetic growth media. Neocallimastigomycota are a group of strictly anaerobic fungi which, instead of containing sterols, contain the pentacyclic triterpenoid "sterol surrogate" tetrahymanol, which is formed by cyclization of squalene. Here, we demonstrate that expression of the squalene-tetrahymanol cyclase gene TtTHC1 from the ciliate Tetrahymena thermophila enables synthesis of tetrahymanol by S. cerevisiae. Moreover, expression of TtTHC1 enabled exponential growth of anaerobic S. cerevisiae cultures in sterol-free synthetic media. After deletion of the ERG1 gene from a TiTHC1-expressing S. cerevisiae strain, native sterol synthesis was abolished and sustained sterol-free growth was demonstrated under anaerobic as well as aerobic conditions. Anaerobic cultures of TIT HO-expressing S. cerevisiae on sterol-free medium showed lower specific growth rates and biomass yields than ergosterol-supplemented cultures, while their ethanol yield was higher. This study demonstrated that acquisition of a functional squalene-tetrahymanol cyclase gene offers an immediate growth advantage to S. cerevisiae under anaerobic, sterol-limited conditions and provides the basis for a metabolic engineering strategy to eliminate the oxygen requirements associated with sterol synthesis in yeasts.IMPORTANCE The laboratory experiments described in this report simulate a proposed horizontal gene transfer event during the evolution of strictly anaerobic fungi. The demonstration that expression of a single heterologous gene sufficed to eliminate anaerobic sterol requirements in the model eukaryote Saccharomyces cerevisiae therefore contributes to our understanding of how sterol-independent eukaryotes evolved in anoxic environments. This report provides a proof of principle for a metabolic engineering strategy to eliminate sterol requirements in yeast strains that are applied in large-scale anaerobic industrial processes. The sterol-independent yeast strains described in this report provide a valuable platform for further studies on the physiological roles and impacts of sterols and sterol surrogates in eukaryotic cells. Show less
Identifying and elucidating the functions and activation of GPCRs will provide opportunities for novel drug discovery. We confirmed that a yeast system with an extended library of G... Show more Identifying and elucidating the functions and activation of GPCRs will provide opportunities for novel drug discovery. We confirmed that a yeast system with an extended library of G proteins is very well suited for the study of GPCR activation, G protein coupling profiles, receptor-G protein binding and G protein selectivity. For example, we used a scanning mutagenesis approach of the NPxxY(x)5,6F motif and of helix 8 of the adenosine A2B receptor (A2BR), and learned among others that amino acid residues in these motifs are crucial for receptor function, since alanine mutants of these amino acid residues led to a complete loss of function. Hopefully, such findings can contribute to further drug development. We also focused on structure-kinetics relationship (SKR) studies next to the more traditional Structure-affinity relationship (SAR) studies. We found two compounds showing longer residence times than nicotinic acid, which may provide clues for further drug discovery efforts on this receptor. All in all, the variety of methods described in this thesis provided us a detailed understanding of receptor function, suggesting that novel avenues for further drug discovery on these established targets is entirely feasible. Show less
Image analysis of objects in the microscope scale requires accuracy so that measurements can be used to differentiate between groups of objects that are being studied. This thesis deals... Show more Image analysis of objects in the microscope scale requires accuracy so that measurements can be used to differentiate between groups of objects that are being studied. This thesis deals with measurements in yeast biology that are obtained through microscope images. We study the algorithms and workflow of image analysis of yeast cells in order to understand and improve the measurement accuracy. The Saccharomyces cerevisiae cell is widely used as a model organism in the life sciences. It is essential to study the gene and protein behaviour within these cells, and consequently making it possible to find treatment and solutions for genetic and hereditary diseases. This is possible since many processes that occurs at the molecular level in this organism are similar to those in human cells. In the research group Imaging and Bioinformatics, we have developed a framework for analysis of yeast cells. This framework is intended to serve as a support for research in yeast biology. The framework is integrated in one application and presented via a GUI. The application integrates modules and algorithms including segmentation, measurement, analysis and visualization. Show less
Agrobacterium tumefaciens is a phytopathogen which is known to be the causal agent of crown gall disease in dicotyledonous plants. Virulent Agrobacterium strains are always carrier of a tumor... Show moreAgrobacterium tumefaciens is a phytopathogen which is known to be the causal agent of crown gall disease in dicotyledonous plants. Virulent Agrobacterium strains are always carrier of a tumor-inducing (Ti) plasmid. As a result of the expression of Vir proteins, a section of this plasmid termed the T-DNA is transferred via a type four secretion system (T4SS) as a T-strand to the recipient cell where it can integrate into the genomic DNA of the recipient cell. In this thesis the prerequisites of T-DNA circle formation using yeast as a model were assayed. It was found that the homologous repair (HR) protein Rad52 is of importance to the formation of T-DNA circles. In addition to this, the effects of double strand break (DSB) induction on the efficiency of T-DNA integration via the HR pathway in yeast and the role the nucleosome occupancy of the target locus has on DSB induction were assayed. It was found that a decrease in the nucleosome occupancy of a target locus had no measurable impact on the efficiency of T-DNA integration at this locus. However, the combined translocation of nuclease proteins aimed at the target locus and T-strands during AMT greatly facilitated HR-mediated integration of T-DNA. Show less
Agrobacterium tumefaciens is a gram-negative soil bacterium that induces plant tumors by transferring a segment of DNA, called T-DNA, into plant cells. Under laboratory conditions, Agrobacterium... Show moreAgrobacterium tumefaciens is a gram-negative soil bacterium that induces plant tumors by transferring a segment of DNA, called T-DNA, into plant cells. Under laboratory conditions, Agrobacterium can also transform many different non-plant organisms such as the yeast Saccharomyces cerevisiae. During this process, a number of virulence proteins, including VirF and VirE3, are translocated into the host cell. VirF contains an F-box domain and, according to current theory, in plants and in yeast may induce degradation of the virulence protein VirE2 and the transcription factor VIP1, required for the integration of the T-DNA into host chromosomal DNA. VirE3 functions as a potential plant transcriptional activator. In our study, we expressed the Agrobacterium virulence proteins VirF and VirE3 in Saccharomyces cerevisiae and Arabidopsis thaliana and studied the effect of virF and virE3 expression on the genome-wide transcription in S. cerevisiae and A.thaliana using DNA microarrays and RNA-sequencing. Show less
Boender, L.G.M.; Maris, A.J.A. van; Hulster, E.A.F. de; Almering, M.J.H.; Klei, I.J. van der; Veenhuis, M.; ... ; Daran-Lapujade, P. 2011
Saccharomyces cerevisiae is one of the few yeast species that can grow equally well without molecular oxygen (anaerobic) as with this compound present (aerobic). This property has made it one of... Show moreSaccharomyces cerevisiae is one of the few yeast species that can grow equally well without molecular oxygen (anaerobic) as with this compound present (aerobic). This property has made it one of the most abundantly used yeasts in industry, since anaerobic incubation plays a major part in alcohol and bread industry. With the experiments described in this thesis it has been shown that apart from metabolic changes, an adaptation of the cell wall and the plasma membrane is very important for anaerobic growth. There seems to be a connection between this adaptation and the import of sterols, which are essential when no molecular oxygen is present. The importance of these adaptations becomes clear when the genomes of the facultative anaerobic Saccharomyces cerevisiae and the obligatory aerobic Kluyveromyces lactis are compared. K. lactis does not have any genes that encode for a sterol import system.The adaptation of the cell wall and the plasma membrane to anaerobic conditions is extensive and regulated in a complex way, as is apparent from the transcriptome data. Our experiments show that Snf7 is, at least in part, responsible for these changes. Show less
