Project description:Gliadins proteins make up around 30% of total wheat flour proteins. They are involved in many immune disorders affecting an increasing number of people who eat foods made with wheat flour. The triggering factor is the accumulation in the gut of immunogenic peptides derived from incomplete degradation of gliadins by gastric proteases. Previous research has revealed the effectiveness of sourdough-fermentation technology or related lactic acid bacteria in reducing wheat flour allergenic proteins. However, there are no single yeast cultures for producing reduced allergenicity wheat products. This study evaluated sourdough-related yeast Wickerhamomyces anomalus strains for their ability to hydrolyze gliadin proteins. All yeast strains were able to degrade gliadins and use them as carbon and nitrogen sources. The proliferation of the yeast strains depended on the gliadin addition; complete hydrolysis was observed after 24 h. The strain showing higher proteolytic activity fermented, acceptably wheat flour dough. The gliadin content of the leavened dough was reduced by 50%. Bread made from the W. anomalus-fermented dough showed a 78% reduction in immunogenic α-gliadins. 50% of the decrease was attributed to the proteolytic activity of the yeast cells, and the other 35% to the baking process. These results show the potential of the yeast W. anomalus as a starter for reducing immunogenicity wheat products.
Project description:In this study, we investigated the transcriptional response of the human isolate L. reuteri ATCC 55730 during sourdough fermentation by using whole-genome microarrays. Significant changes of mRNA levels were found for 101 genes involved in diverse cellular processes, e.g., carbohydrate and energy metabolism, cell envelope biosynthesis, exopolysaccharide production, stress responses, signal transduction and cobalamin biosynthesis. Our results evidence extensive changes of the organism’s gene expression to the growth in sourdough as compared to the growth in chemically defined medium, and thus allowed us to uncover pathways involved in the adaptation of L. reuteri to the ecological niche of sourdough. An impact of several genes of L. reuteri for effective growth in sourdough was shown by implementation of mutant strains in sourdough fermentation. This study contributes to the understanding of the molecular fundamentals of L. reuteri’s ecological competitiveness, and provides a basis for further exploration of genetic traits involved in adaptation to the food and/or intestinal environment. Keywords: environment-specific gene expression, sourdough fermentation, chemically defined medium, dye swap
Project description:A fruity aroma-producing yeast strain was isolated with the aim of improving the aroma of fermented lily rice wine, and identified as Wickerhamomyces anomalus HN006. In addition, the effects of adding solid residues of previous fermentation cycles, and of fungus α-amylase and W. anomalus HN006 supplementation on the biochemical parameters of lily rice wine were evaluated. The optimum quality of the wine, in terms of ethanol and residual sugar content, acidity levels and aroma, was obtained with 5% (w/v) solid residue addition, and supplementation with 10 U/g fungal α-amylase and 2% (v/v) W. anomalus inoculum on the 4th day of fermentation. Volatile compound profiles, the total amount of amino acids and the sensory characteristics of the lily rice wines produced by the two fermentation processes were also evaluated and compared. The lily rice wine obtained from our optimized experimental technology produced higher amounts of some esters, free fatty acids, alcohols, aldehydes, ketones, alkenes, volatile phenol and thiazole, in addition to higher total amino acid content and sensory scores compared to the traditionally brewed wine. Our process resulted in an intensification and improvement of lily rice wine aroma.
Project description:Wickerhamomyces anomalus has been previously classified as Hansenula anomala, Pichia anomala, and Candida pelliculosa and was recently reclassified in the genus Wickerhamomyces after phylogenetic analysis of its genetic sequence. An increasing number of reports of human infections by W. anomalus have emerged, suggesting that this microorganism is an emerging pathogen. The present review aimed to provide data on the epidemiology, antifungal resistance, clinical characteristics, treatment, and outcomes of fungemia by W. anomalus by extracting all the available information from published original reports in the literature. PubMed/Medline, Cochrane Library, and Scopus databases were searched for eligible articles reporting data on patients with this disease. In total, 36 studies involving 170 patients were included. The age of patients with fungemia by W. anomalus ranged from 0 to 89 years; the mean age was 22.8 years, the median age was 2.2 years, with more than 37 patients being less than one month old, and 54% (88 out of 163 patients) were male. Regarding patients' history, 70.4% had a central venous catheter use (CVC), 28.7% were on total parenteral nutrition (TPN), 97% of neonates were hospitalized in the neonatal ICU (NICU), and 39.4% of the rest of the patients were hospitalized in the intensive care unit (ICU). Previous antimicrobial use was noted in 65.9% of patients. The most common identification method was the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) in 34.1%, VITEK and VITEK 2 in 20.6%, and ID32 C in 15.3%. W. anomalus had minimal antifungal resistance to fluconazole, echinocandins, and amphotericin B, the most commonly used antifungals for treatment. Fever and sepsis were the most common clinical presentation noted in 95.8% and 86%, respectively. Overall mortality was 20% and was slightly higher in patients older than one year. Due to the rarity of this disease, future multicenter studies should be performed to adequately characterize patients' characteristics, treatment, and outcomes, which will increase our understanding and allow drawing safer conclusions regarding optimal management.
Project description:Sourdough is a very competitive and challenging environment for microorganisms. Usually, a stable microbiota composed of lactic acid bacteria (LAB) and yeasts comes to dominate this ecosystem. Although rich in carbohydrates, thus providing an ideal environment to grow, the low pH presents a particular challenge. The nature of the adaptation to this low pH was investigated for Lactobacillus plantarum IMDO 130201, an isolate from a laboratory wheat sourdough fermentation. Batch fermentations were carried out in wheat sourdough simulation medium, and total RNA was isolated from mid-exponential growth phase cultures, followed by differential gene expression analysis using a LAB functional gene microarray. At low pH values, an increased expression of genes involved in peptide and amino acid metabolism was observed as well as of genes involved in plantaricin production and lipoteichoic acid synthesis. The results highlight cellular mechanisms that allow L. plantarum to function at a low environmental pH.