scholarly journals Responses of Saccharomyces cerevisiae Strains from Different Origins to Elevated Iron Concentrations

2016 ◽  
Vol 82 (6) ◽  
pp. 1906-1916 ◽  
Author(s):  
Carlos Andrés Martínez-Garay ◽  
Rosa de Llanos ◽  
Antonia María Romero ◽  
María Teresa Martínez-Pastor ◽  
Sergi Puig
Keyword(s):  
Oxidative Stress ◽  
Saccharomyces Cerevisiae ◽  
Iron Deficiency ◽  
Iron Concentration ◽  
Yeast Cells ◽  
Deficiency Anemia ◽  
Content Type ◽  
Yeast Strains ◽  
Resistant Strains ◽  
Iron Concentrations

ABSTRACTIron is an essential micronutrient for all eukaryotic organisms. However, the low solubility of ferric iron has tremendously increased the prevalence of iron deficiency anemia, especially in women and children, with dramatic consequences. Baker's yeastSaccharomyces cerevisiaeis used as a model eukaryotic organism, a fermentative microorganism, and a feed supplement. In this report, we explore the genetic diversity of 123 wild and domestic strains ofS. cerevisiaeisolated from different geographical origins and sources to characterize how yeast cells respond to elevated iron concentrations in the environment. By using two different forms of iron, we selected and characterized both iron-sensitive and iron-resistant yeast strains. We observed that when the iron concentration in the medium increases, iron-sensitive strains accumulate iron more rapidly than iron-resistant isolates. We observed that, consistent with excess iron leading to oxidative stress, the redox state of iron-sensitive strains was more oxidized than that of iron-resistant strains. Growth assays in the presence of different oxidative reagents ruled out that this phenotype was due to alterations in the general oxidative stress protection machinery. It was noteworthy that iron-resistant strains were more sensitive to iron deficiency conditions than iron-sensitive strains, which suggests that adaptation to either high or low iron is detrimental for the opposite condition. An initial gene expression analysis suggested that alterations in iron homeostasis genes could contribute to the different responses of distant iron-sensitive and iron-resistant yeast strains to elevated environmental iron levels.

scholarly journals Soybean Ferritin Expression in Saccharomyces cerevisiae Modulates Iron Accumulation and Resistance to Elevated Iron Concentrations

2016 ◽  
Vol 82 (10) ◽  
pp. 3052-3060 ◽  
Author(s):  
Rosa de Llanos ◽  
Carlos Andrés Martínez-Garay ◽  
Josep Fita-Torró ◽  
Antonia María Romero ◽  
María Teresa Martínez-Pastor ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Iron Deficiency ◽  
Iron Metabolism ◽  
Soybean Seed ◽  
Iron Accumulation ◽  
Yeast Cells ◽  
Nutritional Disorder ◽  
Iron Storage ◽  
Content Type ◽  
Iron Concentrations

ABSTRACTFungi, including the yeastSaccharomyces cerevisiae, lack ferritin and use vacuoles as iron storage organelles. This work explored how plant ferritin expression influenced baker's yeast iron metabolism. Soybean seed ferritin H1 (SFerH1) and SFerH2 genes were cloned and expressed in yeast cells. Both soybean ferritins assembled as multimeric complexes, which bound yeast intracellular ironin vivoand, consequently, induced the activation of the genes expressed during iron scarcity. Soybean ferritin protected yeast cells that lacked the Ccc1 vacuolar iron detoxification transporter from toxic iron levels by reducing cellular oxidation, thus allowing growth at high iron concentrations. Interestingly, when simultaneously expressed inccc1Δ cells, SFerH1 and SFerH2 assembled as heteropolymers, which further increased iron resistance and reduced the oxidative stress produced by excess iron compared to ferritin homopolymer complexes. Finally, soybean ferritin expression led to increased iron accumulation in both wild-type andccc1Δ yeast cells at certain environmental iron concentrations.IMPORTANCEIron deficiency is a worldwide nutritional disorder to which women and children are especially vulnerable. A common strategy to combat iron deficiency consists of dietary supplementation with inorganic iron salts, whose bioavailability is very low. Iron-enriched yeasts and cereals are alternative strategies to diminish iron deficiency. Animals and plants possess large ferritin complexes that accumulate, detoxify, or buffer excess cellular iron. However, the yeastSaccharomyces cerevisiaelacks ferritin and uses vacuoles as iron storage organelles. Here, we explored how soybean ferritin expression influenced yeast iron metabolism, confirming that yeasts that express soybean seed ferritin could be explored as a novel strategy to increase dietary iron absorption.

scholarly journals Sml1 Inhibits the DNA Repair Activity of Rev1 in Saccharomyces cerevisiae during Oxidative Stress

2020 ◽  
Vol 86 (7) ◽  
Author(s):  
Rui Yao ◽  
Pei Zhou ◽  
Chengjin Wu ◽  
Liming Liu ◽  
Jing Wu
Keyword(s):  
Oxidative Stress ◽  
Saccharomyces Cerevisiae ◽  
Dna Damage ◽  
Survival Rate ◽  
Type Strain ◽  
Mutation Frequency ◽  
Wild Type Strain ◽  
Yeast Cells ◽  
Wild Type ◽  
Content Type

ABSTRACT In Saccharomyces cerevisiae, Y family DNA polymerase Rev1 is involved in the repair of DNA damage by translesion DNA synthesis (TLS). In the current study, to elucidate the role of Rev1 in oxidative stress-induced DNA damage in S. cerevisiae, REV1 was deleted and overexpressed; transcriptome analysis of these mutants along with the wild-type strain was performed to screen potential genes that could be associated with REV1 during response to DNA damage. When the yeast cells were treated with 2 mM H2O2, the deletion of REV1 resulted in a 1.5- and 2.8-fold decrease in the survival rate and mutation frequency, respectively, whereas overexpression of REV1 increased the survival rate and mutation frequency by 1.1- and 2.9-fold, respectively, compared to the survival rate and mutation frequency of the wild-type strain. Transcriptome and phenotypic analyses identified that Sml1 aggravated oxidative stress in the yeast cells by inhibiting the activity of Rev1. This inhibition was due to the physical interaction between the BRCA1 C terminus (BRCT) domain of Rev1 and amino acid residues 36 to 70 of Sml1; the cell survival rate and mutation frequency increased by 1.8- and 3.1-fold, respectively, when this interaction was blocked. We also found that Sml1 inhibited Rev1 phosphorylation under oxidative stress and that deletion of SML1 increased the phosphorylation of Rev1 by 46%, whereas overexpression of SML1 reduced phosphorylation of Rev1. Overall, these findings demonstrate that Sml1 could be a novel regulator that mediates Rev1 dephosphorylation to inhibit its activity during oxidative stress. IMPORTANCE Rev1 was critical for cell growth in S. cerevisiae, and the deletion of REV1 caused a severe growth defect in cells exposed to oxidative stress (2 mM H2O2). Furthermore, we found that Sml1 physically interacted with Rev1 and inhibited Rev1 phosphorylation, thereby inhibiting Rev1 DNA antioxidant activity. These findings indicate that Sml1 could be a novel regulator for Rev1 in response to DNA damage by oxidative stress.

scholarly journals A Loss-of-Function Mutation in the PAS Kinase Rim15p Is Related to Defective Quiescence Entry and High Fermentation Rates of Saccharomyces cerevisiae Sake Yeast Strains

2012 ◽  
Vol 78 (11) ◽  
pp. 4008-4016 ◽  
Author(s):  
Daisuke Watanabe ◽  
Yuya Araki ◽  
Yan Zhou ◽  
Naoki Maeya ◽  
Takeshi Akao ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Frameshift Mutation ◽  
Laboratory Strain ◽  
Underlying Mechanism ◽  
Yeast Cells ◽  
Quiescent State ◽  
Loss Of Function ◽  
Content Type ◽  
Yeast Strains ◽  
Pas Kinase

ABSTRACTSake yeast cells have defective entry into the quiescent state, allowing them to sustain high fermentation rates. To reveal the underlying mechanism, we investigated the PAS kinase Rim15p, which orchestrates initiation of the quiescence program inSaccharomyces cerevisiae. We found that Rim15p is truncated at the carboxyl terminus in modern sake yeast strains as a result of a frameshift mutation. Introduction of this mutation or deletion of the full-lengthRIM15gene in a laboratory strain led to a defective stress response, decreased synthesis of the storage carbohydrates trehalose and glycogen, and impaired G1arrest, which together closely resemble the characteristic phenotypes of sake yeast. Notably, expression of a functionalRIM15gene in a modern sake strain suppressed all of these phenotypes, demonstrating that dysfunction of Rim15p prevents sake yeast cells from entering quiescence. Moreover, loss of Rim15p or its downstream targets Igo1p and Igo2p remarkably improved the fermentation rate in a laboratory strain. This finding verified that Rim15p-mediated entry into quiescence plays pivotal roles in the inhibition of ethanol fermentation. Taken together, our results suggest that the loss-of-function mutation in theRIM15gene may be the key genetic determinant of the increased ethanol production rates in modern sake yeast strains.

scholarly journals Nutrient Signaling via the TORC1-Greatwall-PP2AB55δ Pathway Is Responsible for the High Initial Rates of Alcoholic Fermentation in Sake Yeast Strains of Saccharomyces cerevisiae

2018 ◽  
Vol 85 (1) ◽  
Author(s):  
Daisuke Watanabe ◽  
Takuma Kajihara ◽  
Yukiko Sugimoto ◽  
Kenichi Takagi ◽  
Megumi Mizuno ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Kinase ◽  
Alcoholic Fermentation ◽  
Yeast Cells ◽  
Loss Of Function ◽  
Fermentation Performance ◽  
Content Type ◽  
Yeast Strains ◽  
Evolutionarily Conserved ◽  
Fermentation Control

ABSTRACT Saccharomyces cerevisiae sake yeast strain Kyokai no. 7 (K7) and its relatives carry a homozygous loss-of-function mutation in the RIM15 gene, which encodes a Greatwall family protein kinase. Disruption of RIM15 in nonsake yeast strains leads to improved alcoholic fermentation, indicating that the defect in Rim15p is associated with the enhanced fermentation performance of sake yeast cells. In order to understand how Rim15p mediates fermentation control, we here focused on target-of-rapamycin protein kinase complex 1 (TORC1) and protein phosphatase 2A with the B55δ regulatory subunit (PP2AB55δ), complexes that are known to act upstream and downstream of Rim15p, respectively. Several lines of evidence, including our previous transcriptomic analysis data, suggested enhanced TORC1 signaling in sake yeast cells during sake fermentation. Fermentation tests of the TORC1-related mutants using a laboratory strain revealed that TORC1 signaling positively regulates the initial fermentation rate in a Rim15p-dependent manner. Deletion of the CDC55 gene, encoding B55δ, abolished the high fermentation performance of Rim15p-deficient laboratory yeast and sake yeast cells, indicating that PP2AB55δ mediates the fermentation control by TORC1 and Rim15p. The TORC1-Greatwall-PP2AB55δ pathway similarly affected the fermentation rate in the fission yeast Schizosaccharomyces pombe, strongly suggesting that the evolutionarily conserved pathway governs alcoholic fermentation in yeasts. It is likely that elevated PP2AB55δ activity accounts for the high fermentation performance of sake yeast cells. Heterozygous loss-of-function mutations in CDC55 found in K7-related sake strains may indicate that the Rim15p-deficient phenotypes are disadvantageous to cell survival. IMPORTANCE The biochemical processes and enzymes responsible for glycolysis and alcoholic fermentation by the yeast S. cerevisiae have long been the subject of scientific research. Nevertheless, the factors determining fermentation performance in vivo are not fully understood. As a result, the industrial breeding of yeast strains has required empirical characterization of fermentation by screening numerous mutants through laborious fermentation tests. To establish a rational and efficient breeding strategy, key regulators of alcoholic fermentation need to be identified. In the present study, we focused on how sake yeast strains of S. cerevisiae have acquired high alcoholic fermentation performance. Our findings provide a rational molecular basis to design yeast strains with optimal fermentation performance for production of alcoholic beverages and bioethanol. In addition, as the evolutionarily conserved TORC1-Greatwall-PP2AB55δ pathway plays a major role in the glycolytic control, our work may contribute to research on carbohydrate metabolism in higher eukaryotes.

Fortification of tempeh with encapsulated iron improves iron status and gut microbiota composition in iron deficiency anemia condition

2018 ◽  
Vol 48 (6) ◽  
pp. 962-972 ◽  
Author(s):  
Rio Jati Kusuma ◽  
Aviria Ermamilia
Keyword(s):  
Iron Deficiency ◽  
Gut Microbiota ◽  
Iron Deficiency Anemia ◽  
Iron Status ◽  
Deficiency Anemia ◽  
Microbiota Composition ◽  
Iron Fortification ◽  
Iron Matrix ◽  
Content Type ◽  
Gut Microbiota Composition

Purpose Iron deficiency anemia (IDA) is one of the most major micronutrient deficiencies worldwide. Food fortification is one strategy for reducing IDA in the population despite concern regarding the gut pathogenic bacteria overgrowth. The purpose of this study was to evaluate the effect of iron encapsulation in banana peel matrix on iron status and gut microbiota composition in iron deficiency anemia. Design/methodology/approach Anemia was induced in 35 male Sprague Dawley rats of age two weeks by the administration of iron-free diet for two weeks. Rats then randomly divided into control, iron-fortified tempeh (temFe) dose 10 and 20 ppm, iron matrix-fortified tempeh dose 10 and 20 ppm and iron matrix fortified tempeh dose 10 and 20 ppm with probiotic mixture. Blood was drawn at Weeks 2 and 6 for hemoglobin and serum iron analysis. Rats were sacrificed at the end of Week 6, and cecal contents were collected for Lactobacillus, Bifidobacteria and Enterobactericeae analysis. Findings Hemoglobin and serum iron were significantly increased (p < 0.05) in all iron-fortified group with the highest value found in iron matrix dose 20 ppm (10.71 ± 0.15 g/dl and 335.83 ± 2.17 µg/dl, respectively). The cecal Lactobacillus and Bifidobacteria did not differ significantly between groups. Cecal Enterobactericeae was significantly different (p < 0.05) among groups with the lowest level in the temFe-20 (2.65 ± 0.78 log CFU) group. Research limitations/implications The use of commercial inoculum instead of pure Rhizopus oligosporus mold for developing the fortified tempeh may impact the effect of product on cecal gut microbiota composition, as different molds and lactic acid bacteria can grow in tempeh when using commercial inoculum. Social implications In Indonesia, iron fortification is conducted primarily in noodles and flour that limits the impact of iron fortification for reducing IDA in population. Iron fortification in food that was daily consumed by people, that is, tempeh, is potential strategy in reducing IDA in population. Originality/value Tempeh fortification using encapsulated iron improved iron status and gut microbiota composition in iron deficiency anemia.

scholarly journals New Lager Brewery Strains Obtained by Crossing Techniques Using Cachaça (Brazilian Spirit) Yeasts

2017 ◽  
Vol 83 (20) ◽  
Author(s):  
Bruna Inez Carvalho Figueiredo ◽  
Margarete Alice Fontes Saraiva ◽  
Paloma Patrick de Souza Pimenta ◽  
Miriam Conceição de Souza Testasicca ◽  
Geraldo Magela Santos Sampaio ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Low Temperature ◽  
Yeast Strain ◽  
Genetically Modified ◽  
Acetate Esters ◽  
Content Type ◽  
Yeast Strains ◽  
Lager Beer ◽  
New Yeast ◽  
Beer Production

ABSTRACT The development of hybrids has been an effective approach to generate novel yeast strains with optimal technological profile for use in beer production. This study describes the generation of a new yeast strain for lager beer production by direct mating between two Saccharomyces cerevisiae strains isolated from cachaça distilleries: one that was strongly flocculent, and the other with higher production of acetate esters. The first step in this procedure was to analyze the sporulation ability and reproductive cycle of strains belonging to a specific collection of yeasts isolated from cachaça fermentation vats. Most strains showed high rates of sporulation, spore viability, and homothallic behavior. In order to obtain new yeast strains with desirable properties useful for lager beer production, we compare haploid-to-haploid and diploid-to-diploid mating procedures. Moreover, an assessment of parental phenotype traits showed that the segregant diploid C2-1d generated from a diploid-to-diploid mating experiment showed good fermentation performance at low temperature, high flocculation capacity, and desirable production of acetate esters that was significantly better than that of one type lager strain. Therefore, strain C2-1d might be an important candidate for the production of lager beer, with distinct fruit traces and originating using a non-genetically modified organism (GMO) approach. IMPORTANCE Recent work has suggested the utilization of hybridization techniques for the generation of novel non-genetically modified brewing yeast strains with combined properties not commonly found in a unique yeast strain. We have observed remarkable traits, especially low temperature tolerance, maltotriose utilization, flocculation ability, and production of volatile aroma compounds, among a collection of Saccharomyces cerevisiae strains isolated from cachaça distilleries, which allow their utilization in the production of beer. The significance of our research is in the use of breeding/hybridization techniques to generate yeast strains that would be appropriate for producing new lager beers by exploring the capacity of cachaça yeast strains to flocculate and to ferment maltose at low temperature, with the concomitant production of flavoring compounds.

scholarly journals Ferroportin-Hepcidin Axis in Prepubertal Obese Children with Sufficient Daily Iron Intake

2018 ◽  
Vol 15 (10) ◽  
pp. 2156 ◽  
Author(s):  
Joanna Gajewska ◽  
Jadwiga Ambroszkiewicz ◽  
Witold Klemarczyk ◽  
Ewa Głąb-Jabłońska ◽  
Halina Weker ◽  
...  
Keyword(s):  
Iron Deficiency ◽  
Iron Status ◽  
Hematological Parameters ◽  
Daily Intake ◽  
Normal Weight ◽  
Deficiency Anemia ◽  
Dietary Iron ◽  
Iron Intake ◽  
Obese Children ◽  
Iron Concentrations

Iron metabolism may be disrupted in obesity, therefore, the present study assessed the iron status, especially ferroportin and hepcidin concentrations, as well as associations between the ferroportin-hepcidin axis and other iron markers in prepubertal obese children. The following were determined: serum ferroportin, hepcidin, ferritin, soluble transferrin receptor (sTfR), iron concentrations and values of hematological parameters as well as the daily dietary intake in 40 obese and 40 normal-weight children. The ferroportin/hepcidin and ferritin/hepcidin ratios were almost two-fold lower in obese children (p = 0.001; p = 0.026, respectively). Similar iron concentrations (13.2 vs. 15.2 µmol/L, p = 0.324), the sTfR/ferritin index (0.033 vs. 0.041, p = 0.384) and values of hematological parameters were found in obese and control groups, respectively. Iron daily intake in the obese children examined was consistent with recommendations. In this group, the ferroportin/hepcidin ratio positively correlated with energy intake (p = 0.012), dietary iron (p = 0.003) and vitamin B12 (p = 0.024). In the multivariate regression model an association between the ferroportin/hepcidin ratio and the sTfR/ferritin index in obese children (β = 0.399, p = 0.017) was found. These associations did not exist in the controls. The results obtained suggest that in obese children with sufficient iron intake, the altered ferroportin-hepcidin axis may occur without signs of iron deficiency or iron deficiency anemia. The role of other micronutrients, besides dietary iron, may also be considered in the iron status of these children.

scholarly journals Determination of the Global Pattern of Gene Expression in Yeast Cells by Intracellular Levels of Guanine Nucleotides

mBio ◽  
2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Andy Hesketh ◽  
Marta Vergnano ◽  
Stephen G. Oliver
Keyword(s):  
Gene Expression ◽  
Saccharomyces Cerevisiae ◽  
Carbon Source ◽  
Gene Transcription ◽  
Adenine Nucleotide ◽  
High Energy ◽  
Yeast Cells ◽  
Purine Nucleotides ◽  
Global Pattern ◽  
Content Type

ABSTRACT Correlations between gene transcription and the abundance of high-energy purine nucleotides in Saccharomyces cerevisiae have often been noted. However, there has been no systematic investigation of this phenomenon in the absence of confounding factors such as nutrient status and growth rate, and there is little hard evidence for a causal relationship. Whether transcription is fundamentally responsive to prevailing cellular energetic conditions via sensing of intracellular purine nucleotides, independently of specific nutrition, remains an important question. The controlled nutritional environment of chemostat culture revealed a strong correlation between ATP and GTP abundance and the transcription of genes required for growth. Short pathways for the inducible and futile consumption of ATP or GTP were engineered into S. cerevisiae, permitting analysis of the transcriptional effect of an increased demand for these nucleotides. During steady-state growth using the fermentable carbon source glucose, the futile consumption of ATP led to a decrease in intracellular ATP concentration but an increase in GTP and the guanylate energy charge (GEC). Expression of transcripts encoding proteins involved in ribosome biogenesis, and those controlled by promoters subject to SWI/SNF-dependent chromatin remodelling, was correlated with these nucleotide pool changes. Similar nucleotide abundance changes were observed using a nonfermentable carbon source, but an effect on the growth-associated transcriptional programme was absent. Induction of the GTP-cycling pathway had only marginal effects on nucleotide abundance and gene transcription. The transcriptional response of respiring cells to glucose was dampened in chemostats induced for ATP cycling, but not GTP cycling, and this was primarily associated with altered adenine nucleotide levels. IMPORTANCE This paper investigates whether, independently of the supply of any specific nutrient, gene transcription responds to the energy status of the cell by monitoring ATP and GTP levels. Short pathways for the inducible and futile consumption of ATP or GTP were engineered into the yeast Saccharomyces cerevisiae, and the effect of an increased demand for these purine nucleotides on gene transcription was analyzed. The resulting changes in transcription were most consistently associated with changes in GTP and GEC levels, although the reprogramming in gene expression during glucose repression is sensitive to adenine nucleotide levels. The results show that GTP levels play a central role in determining how genes act to respond to changes in energy supply and that any comprehensive understanding of the control of eukaryotic gene expression requires the elucidation of how changes in guanine nucleotide abundance are sensed and transduced to alter the global pattern of transcription.

scholarly journals Siderophore (from Synechococcus sp. PCC 7002)-Chelated Iron Promotes Iron Uptake in Caco-2 Cells and Ameliorates Iron Deficiency in Rats

Marine Drugs ◽  
2019 ◽  
Vol 17 (12) ◽  
pp. 709
Author(s):  
Xue Feng ◽  
Suisui Jiang ◽  
Fan Zhang ◽  
Runfang Wang ◽  
Yuanhui Zhao ◽  
...  
Keyword(s):  
Iron Deficiency ◽  
Rat Model ◽  
Ferrous Sulfate ◽  
Iron Absorption ◽  
Iron Concentration ◽  
Deficiency Anemia ◽  
Absorption Mechanism ◽  
Cell Monolayers ◽  
Chelated Iron ◽  
Synechococcus Sp

Siderophores are iron chelators with low molecular weight secreted by microorganisms. Siderophores have the potential to become natural iron fortifiers. To explore the feasibility of the application of Synechococcus sp. PCC7002-derived siderophores as iron fortifiers, Synechococcus sp. PCC7002, as a carrier, was fermented to produce siderophores. The absorption mechanism and anemia intervention effect of siderophores-chelated iron (SCI) were studied through the polarized Caco-2 Cell monolayers and the rat model of iron-deficiency anemia, respectively. The results indicated that siderophores (from Synechococcus sp. PCC7002) had an enhancing effect on iron absorption in polarized Caco-2 cell monolayers. The main absorption site of SCI was duodenum with pH 5.5, and the absorption methods included endocytosis and DMT1, with endocytosis being dominant. The effect of sodium phytate on SCI was less than that of ferrous sulfate. Therefore, SCI could resist inhibitory iron absorption factors in polarized Caco-2 cell monolayers. SCI showed significantly higher relative bioavailability (133.58 ± 15.42%) than ferrous sulfate (100 ± 14.84%) and ferric citrate (66.34 ± 8.715%) in the rat model. Food intake, hemoglobin concentration, and hematocrit and serum iron concentration of rats improved significantly after Fe-repletion. Overall, this study indicated that siderophores derived from Synechococcus sp. PCC7002 could be an effective and feasible iron nutritive fortifier.

scholarly journals Glucosylceramide Contained in Koji Mold-Cultured Cereal Confers Membrane and Flavor Modification and Stress Tolerance to Saccharomyces cerevisiae during Coculture Fermentation

2015 ◽  
Vol 81 (11) ◽  
pp. 3688-3698 ◽  
Author(s):  
Kazutaka Sawada ◽  
Tomoya Sato ◽  
Hiroshi Hamajima ◽  
Lahiru Niroshan Jayakody ◽  
Miyo Hirata ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Acetic Acid Bacteria ◽  
Yeast Cells ◽  
Membrane Properties ◽  
Yeast Culture ◽  
Content Type ◽  
Initial Stage ◽  
Alkaline Conditions ◽  
Metabolic Interactions ◽  
Alkali Tolerance

ABSTRACTIn nature, different microorganisms create communities through their physiochemical and metabolic interactions. Many fermenting microbes, such as yeasts, lactic acid bacteria, and acetic acid bacteria, secrete acidic substances and grow faster at acidic pH values. However, on the surface of cereals, the pH is neutral to alkaline. Therefore, in order to grow on cereals, microbes must adapt to the alkaline environment at the initial stage of colonization; such adaptations are also crucial for industrial fermentation. Here, we show that the yeastSaccharomyces cerevisiae, which is incapable of synthesizing glucosylceramide (GlcCer), adapted to alkaline conditions after exposure to GlcCer from koji cereal cultured withAspergillus kawachii. We also show that various species of GlcCer derived from different plants and fungi similarly conferred alkali tolerance to yeast. Although exogenous ceramide also enhanced the alkali tolerance of yeast, no discernible degradation of GlcCer to ceramide was observed in the yeast culture, suggesting that exogenous GlcCer itself exerted the activity. Exogenous GlcCer also increased ethanol tolerance and modified the flavor profile of the yeast cells by altering the membrane properties. These results indicate that GlcCer fromA. kawachiimodifies the physiology of the yeastS. cerevisiaeand demonstrate a new mechanism for cooperation between microbes in food fermentation.

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