scholarly journals Temperature-dependent genetics of thermotolerance between yeast species

2022 ◽  
Author(s):  
Melanie Bernette Abrams ◽  
Rachel B Brem
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Yeast Species ◽  
Molecular Genetic ◽  
Test Case ◽  
Temperature Dependent ◽  
Temperature Growth ◽  
Adaptive Mutations ◽  
Focal Species ◽  
Biological Interest ◽  
Genetic Mechanisms

Many traits of industrial and basic biological interest arose long ago, and manifest now as fixed differences between a focal species and its reproductively isolated relatives. In these systems, extant individuals can hold clues to the mechanisms by which phenotypes evolved in their ancestors. We harnessed yeast thermotolerance as a test case for such molecular-genetic inferences. In viability experiments, we showed that extant Saccharomyces cerevisiae survived at temperatures where cultures of its sister species S. paradoxus died out. Then, focusing on loci that contribute to this difference, we found that the genetic mechanisms of high-temperature growth changed with temperature. We also uncovered a robust signature of positive selection at thermotolerance loci in S. cerevisiae population sequences. We interpret these results in light of a model of gradual acquisition of thermotolerance in the S. cerevisiae lineage along a temperature cline. We propose that in an ancestral S. cerevisiae population, alleles conferring defects at a given temperature would have been resolved by adaptive mutations, expanding the range and setting the stage for further temperature advances. Together, our results and interpretation underscore the power of genetic approaches to explore how an ancient trait came to be.

Inhibition of Yeast Growth by Tryptamine and Recovery with Tryptophan

2020 ◽  
Vol 16 (1) ◽  
pp. 48-52 ◽  
Author(s):  
Chandrika Kadkol ◽  
Ian Macreadie
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Carbon Source ◽  
Competitive Inhibition ◽  
Yeast Species ◽  
Inhibitory Effect ◽  
The Body ◽  
Inhibitory Effects ◽  
Trna Synthetases ◽  
Fermentative Growth ◽  
Biogenic Monoamine

Background: Tryptamine, a biogenic monoamine that is present in trace levels in the mammalian central nervous system, has probable roles as a neurotransmitter and/or a neuromodulator and may be associated with various neuropsychiatric disorders. One of the ways tryptamine may affect the body is by the competitive inhibition of the attachment of tryptophan to tryptophanyl tRNA synthetases. Methods: This study has explored the effects of tryptamine on growth of six yeast species (Saccharomyces cerevisiae, Candida glabrata, C. krusei, C. dubliniensis, C. tropicalis and C. lusitaniae) in media with glucose or ethanol as the carbon source, as well as recovery of growth inhibition by the addition of tryptophan. Results: Tryptamine was found to have an inhibitory effect on respiratory growth of all yeast species when grown with ethanol as the carbon source. Tryptamine also inhibited fermentative growth of Saccharomyces cerevisiae, C. krusei and C. tropicalis with glucose as the carbon source. In most cases the inhibitory effects were reduced by added tryptophan. Conclusion: The results obtained in this study are consistent with tryptamine competing with tryptophan to bind mitochondrial and cytoplasmic tryptophanyl tRNA synthetases in yeast: effects on mitochondrial and cytoplasmic protein synthesis can be studied as a function of growth with glucose or ethanol as a carbon source. Of the yeast species tested, there is variation in the sensitivity to tryptamine and the rescue by tryptophan. The current study suggests appropriate yeast strains and approaches for further studies.

An investigation into yeast-baculovirus synergism for the improved control of Thaumatotibia leucotreta, an economically important pest of citrus

2021 ◽  
Author(s):  
◽  
Marcél Van der Merwe
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Yeast Species ◽  
Larval Mortality ◽  
Cydia Pomonella ◽  
Oviposition Preference ◽  
Field Trials ◽  
Multiple Choice Tests ◽  
Thaumatotibia Leucotreta ◽  
Choice Tests ◽  
Pichia Kluyveri

A mutualistic association between Cydia pomonella and yeasts belonging to the genus Metschnikowia has previously been demonstrated. Larval feeding galleries inoculated with M. andauensis, reduced larval mortality and enhanced larval development. Additionally, adult C. pomonella female oviposition preference was also shown to be influenced by the volatiles produced by M. andauensis. This mutualistic relationship was manipulated for biological control purposes, by combining M. pulcherrima with the baculovirus Cydia pomonella granulovirus. The combination of M. pulcherrima with brown cane sugar and CpGV in laboratory assays and field trials resulted in a significant increase in larval mortality. A similar observation was made when M. pulcherrima was substituted for Saccharomyces cerevisiae. This indicates that yeasts harbour the potential for use in biological control, especially when combined with other well-established biocontrol methods. Thaumatotibia leucotreta is a phytophagous insect endemic to southern Africa. It is highly significant to the South African citrus industry due to its classification as a phytosanitary pest by most international markets. An integrated pest management programme has been implemented to control T. leucotreta. The baculovirus Cryptophlebia leucotreta granulovirus forms one component of this programme and is highly effective. In this study, we proposed to determine which yeast species occur naturally in the gut of T. leucotreta larvae and to examine whether any of the isolated yeast species, when combined with the CrleGV-SA, enhance its effectiveness. Firstly, Navel oranges infested with T. leucotreta larvae were collected from geographically distinct citrus-producing regions across South Africa. This led to the isolation and identification of six yeast species from the gut of T. leucotreta larvae via PCR amplification and sequencing of the internal transcribed spacer region and D1/D2 domain of the large subunit. Six yeast species were identified, viz. Meyerozyma guilliermondii, Hanseniaspora uvarum, Clavispora lusitaniae, Kluyveromyces marxianus, Pichia kudriavzevii and Pichia kluyveri. Additionally, Saccharomyces cerevisiae was included as a control in all trials due to its commercial availability and use in the artificial diet used to rear T. leucotreta. Secondly, larval development and attraction assays were conducted with the isolated yeast species. Thaumatotibia leucotreta larvae that fed on Navel oranges inoculated with M. guilliermondii, P. kluyveri, H. uvarum, and S. cerevisiae had accelerated developmental periods and reduced mortality rates. Additionally, it was demonstrated that T. leucotreta neonates were attracted to YPD broth cultures inoculated with P. kluyveri, H. uvarum, P. kudriavzevii and K. marxianus for feeding. Thirdly, oviposition preference assays were conducted with adult T. leucotreta females to determine whether the isolated yeast species influence their egg-laying in two-choice and multiple-choice tests. Navel oranges were inoculated with a specific yeast isolate, and mated adult females were left to oviposit. Meyerozyma guilliermondii, P. kudriavzevii and H. uvarum were shown to influence adult T. leucotreta female oviposition preference in two-choice tests. However, multiple-choice tests using the aforementioned yeast species did not mimic these results. Lastly, a series of detached fruit bioassays were performed to determine the optimal yeast:virus ratio, test all isolated yeast species in combination with CrleGV-SA and to further enhance yeast/virus formulation through the addition of an adjuvant and surfactant. CrleGV-SA was applied at a lethal concentration that would kill 50 % of T. leucotreta larvae. The optimal yeast concentration to use alongside CrleGV-SA was determined. Pichia kluyveri, P. kudriavzevii, K. marxianus and S. cerevisiae in combination with CrleGV-SA increased larval mortality compared to CrleGV-SA alone. The inclusion of molasses and BREAK-THRU® S 240 to P. kudriavzevii and S. cerevisiae plus CrleGV-SA formulations greatly enhanced their efficacy. Additionally, semi-field trials were initiated using P. kudriavzevii and S. cerevisiae, with promising preliminary results being obtained, although more replicates need to be performed. The experiments performed in this study provide a platform for further research into the application of a yeast/virus combination as a novel control and monitoring option for T. leucotreta in the field.

scholarly journals Method-Dependent Epidemiological Cutoff Values for Detection of Triazole Resistance in Candida and Aspergillus Species for the Sensititre YeastOne Colorimetric Broth and Etest Agar Diffusion Methods

2018 ◽  
Vol 63 (1) ◽  
Author(s):  
A. Espinel-Ingroff ◽  
J. Turnidge ◽  
A. Alastruey-Izquierdo ◽  
F. Botterel ◽  
E. Canton ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Species Complex ◽  
Susceptibility Testing ◽  
Yeast Species ◽  
Sensu Stricto ◽  
Wild Type ◽  
Pichia Kudriavzevii ◽  
Cutoff Value ◽  
Content Type ◽  
Clavispora Lusitaniae

ABSTRACT Although the Sensititre Yeast-One (SYO) and Etest methods are widely utilized, interpretive criteria are not available for triazole susceptibility testing of Candida or Aspergillus species. We collected fluconazole, itraconazole, posaconazole, and voriconazole SYO and Etest MICs from 39 laboratories representing all continents for (method/agent-dependent) 11,171 Candida albicans, 215 C. dubliniensis, 4,418 C. glabrata species complex, 157 C. guilliermondii (Meyerozyma guilliermondii), 676 C. krusei (Pichia kudriavzevii), 298 C. lusitaniae (Clavispora lusitaniae), 911 C. parapsilosis sensu stricto, 3,691 C. parapsilosis species complex, 36 C. metapsilosis, 110 C. orthopsilosis, 1,854 C. tropicalis, 244 Saccharomyces cerevisiae, 1,409 Aspergillus fumigatus, 389 A. flavus, 130 A. nidulans, 233 A. niger, and 302 A. terreus complex isolates. SYO/Etest MICs for 282 confirmed non-wild-type (non-WT) isolates were included: ERG11 (C. albicans), ERG11 and MRR1 (C. parapsilosis), cyp51A (A. fumigatus), and CDR2 and CDR1 overexpression (C. albicans and C. glabrata, respectively). Interlaboratory modal agreement was superior by SYO for yeast species and by the Etest for Aspergillus spp. Distributions fulfilling CLSI criteria for epidemiological cutoff value (ECV) definition were pooled, and we proposed SYO ECVs for S. cerevisiae and 9 yeast and 3 Aspergillus species and Etest ECVs for 5 yeast and 4 Aspergillus species. The posaconazole SYO ECV of 0.06 µg/ml for C. albicans and the Etest itraconazole ECV of 2 µg/ml for A. fumigatus were the best predictors of non-WT isolates. These findings support the need for method-dependent ECVs, as, overall, the SYO appears to perform better for susceptibility testing of yeast species and the Etest appears to perform better for susceptibility testing of Aspergillus spp. Further evaluations should be conducted with more Candida mutants.

scholarly journals Screening of whole yeast free-cells and optimization of pH and temperature for fructooligosaccharides production

2017 ◽  
Vol 39 (2) ◽  
pp. 189
Author(s):  
Flávia Deffert ◽  
Bruna Carla Agustini ◽  
Geraldo Picheth ◽  
Tania Maria Bordin Bonfim
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Maximum Concentration ◽  
Lower Cost ◽  
Yeast Species ◽  
Molecular Techniques ◽  
Free Cells ◽  
Influence Of Ph

Fructooligosaccharides are catalyzed by β–fructofuranosidase enzyme, produced by many microorganisms. However, in order to achieve a more profitable, low time-consuming process with lower cost, researchers have sought alternatives. This study aimed to select and identify yeasts able to produce fructooligosaccharides and evaluate the influence of pH and temperature on their synthesis. Yeast suspensions, solutions of 500 g L-1 sucrose and three values of pH (4.5, 5.5, and 6.5) and temperature (40, 50, and 60ºC) were tested. Yeast species were identified by molecular techniques. Among 141 yeast isolates from grapes, 65 were able to synthesize fructooligosaccharides. The maximum concentration of fructooligosaccharides was 4.8% (w v-1), and Saccharomyces cerevisiae 222 produced 1-kestose and nystose. 

scholarly journals Evolutionary adaptation after crippling cell polarization follows reproducible trajectories

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Liedewij Laan ◽  
John H Koschwanez ◽  
Andrew W Murray
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Polarization ◽  
Functional Modules ◽  
Evolutionary Adaptation ◽  
Biological Functions ◽  
Fixed Sequence ◽  
Evolutionary Trajectory ◽  
Adaptive Mutations ◽  
Rapid Divergence ◽  
Polarity Gene

Cells are organized by functional modules, which typically contain components whose removal severely compromises the module's function. Despite their importance, these components are not absolutely conserved between parts of the tree of life, suggesting that cells can evolve to perform the same biological functions with different proteins. We evolved Saccharomyces cerevisiae for 1000 generations without the important polarity gene BEM1. Initially the bem1∆ lineages rapidly increase in fitness and then slowly reach >90% of the fitness of their BEM1 ancestors at the end of the evolution. Sequencing their genomes and monitoring polarization reveals a common evolutionary trajectory, with a fixed sequence of adaptive mutations, each improving cell polarization by inactivating proteins. Our results show that organisms can be evolutionarily robust to physiologically destructive perturbations and suggest that recovery by gene inactivation can lead to rapid divergence in the parts list for cell biologically important functions.

scholarly journals Divergent MLS1 promoters lie on a fitness plateau for gene expression

2015 ◽  
Author(s):  
Andrew C Bergen ◽  
Gerilyn M Olsen ◽  
Justin C Fay
Keyword(s):  
Gene Expression ◽  
Saccharomyces Cerevisiae ◽  
Dynamic Response ◽  
Yeast Species ◽  
Glucose Repression ◽  
Gene Activation ◽  
Malate Synthase ◽  
Expression Divergence ◽  
Fitness Effects ◽  
Single Promoter

Qualitative patterns of gene activation and repression are often conserved despite an abundance of quantitative variation in expression levels within and between species. A major challenge to interpreting patterns of expression divergence is knowing which changes in gene expression affect fitness. To characterize the fitness effects of gene expression divergence we placed orthologous promoters from eight yeast species upstream of malate synthase (MLS1) in Saccharomyces cerevisiae. As expected, we found these promoters varied in their expression level under activated and repressed conditions as well as in their dynamic response following loss of glucose repression. Despite these differences, only a single promoter driving near basal levels of expression caused a detectable loss of fitness. We conclude that the MLS1 promoter lies on a fitness plateau whereby even large changes in gene expression can be tolerated without a substantial loss of fitness.

Sign in / Sign up

Export Citation Format

Share Document