scholarly journals Evolution of ecological dominance of yeast species in high-sugar environments

2015 ◽  
Author(s):  
Kathryn M Williams ◽  
Ping Liu ◽  
Justin C Fay
Keyword(s):  
Growth Rate ◽  
Yeast Species ◽  
Grape Juice ◽  
Relative Fitness ◽  
Intrinsic Growth Rate ◽  
Multiple Traits ◽  
High Sugar ◽  
Ecological Dominance ◽  
Fermentative Yeast ◽  
Wine Fermentations

In budding yeasts, fermentation in the presence of oxygen evolved around the time of a whole genome duplication (WGD) and is thought to confer dominance in high-sugar environments because ethanol is toxic to many species. While there are many fermentative yeast species, only Saccharomyces cerevisiae consistently dominates wine fermentations. In this study, we use co-culture experiments and intrinsic growth rate assays to examine the relative fitness of non-WGD and WGD yeast species across environments to assess when S. cerevisiae's ability to dominate high-sugar environments arose. We show that S. cerevisiae dominates nearly all other non-WGD and WGD species except for its sibling species S. paradoxus in both grape juice and a high-sugar rich medium. Of the species we tested, S. cerevisiae and S. paradoxus have evolved the highest ethanol tolerance and intrinsic growth rate in grape juice. However, the ability of S. cerevisiae and S. paradoxus to dominate certain species depends on the temperature and the type of high-sugar environment. Our results indicate that dominance of high-sugar environments evolved much more recently than the WGD, most likely just prior to or during the differentiation of Saccharomyces species, and that evolution of multiple traits contributes to S. cerevisiae's ability to dominate wine fermentations.

scholarly journals Evolution of ecological dominance of yeast species in high‐sugar environments

Evolution ◽  
2015 ◽  
Vol 69 (8) ◽  
pp. 2079-2093 ◽  
Author(s):  
Kathryn M. Williams ◽  
Ping Liu ◽  
Justin C. Fay
Keyword(s):  
Yeast Species ◽  
High Sugar ◽  
Ecological Dominance

scholarly journals Qualitative Analysis of the Effect of Weeds Removal in Paddy Ecosystems in Fallow Season

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Leru Zhou ◽  
Zhigang Liu ◽  
Tiejun Zhou
Keyword(s):  
Growth Rate ◽  
Equilibrium State ◽  
Excretion Rate ◽  
Critical Value ◽  
Inorganic Fertilizer ◽  
Paddy Fields ◽  
Asymptotically Stable ◽  
Intrinsic Growth Rate ◽  
Stable Conditions ◽  
Coexistence Equilibrium

In the paper, we introduce a differential equations model of paddy ecosystems in the fallow season to study the effect of weeds removal from the paddy fields. We found that there is an unstable equilibrium of the extinction of weeds and herbivores in the system. When the intensity of weeds removal meets certain conditions and the intrinsic growth rate of herbivores is higher than their excretion rate, there is a coexistence equilibrium state in the system. By linearizing the system and using the Routh–Hurwitz criterion, we obtained the local asymptotically stable conditions of the coexistence equilibrium state. The critical value formula of the Hopf bifurcation is presented too. The model demonstrates that weeds removal from paddy fields could largely reduce the weeds biomass in the equilibrium state, but it also decreases the herbivore biomass, which probably reduces the content of inorganic fertilizer in the soil. We found a particular intensity of weeds removal that could result in the minimum content of inorganic fertilizer, suggesting weeds removal should be kept away from this intensity.

scholarly journals ModifyingSaccharomyces cerevisiaeAdhesion Properties Regulates Yeast Ecosystem Dynamics

mSphere ◽  
2018 ◽  
Vol 3 (5) ◽  
Author(s):  
Debra Rossouw ◽  
Skye P. Meiring ◽  
Florian F. Bauer
Keyword(s):  
Gene Expression ◽  
Gene Family ◽  
Yeast Species ◽  
Genetic System ◽  
Physical Contact ◽  
Relative Fitness ◽  
Independent Evidence ◽  
Content Type ◽  
Metabolic Interactions ◽  
The Impact

ABSTRACTPhysical contact between yeast species, in addition to better-understood and reported metabolic interactions, has recently been proposed to significantly impact the relative fitness of these species in cocultures. Such data have been generated by using membrane bioreactors, which physically separate two yeast species. However, doubts persist about the degree that the various membrane systems allow for continuous and complete metabolic contact, including the exchange of proteins. Here, we provide independent evidence for the importance of physical contact by using a genetic system to modify the degree of physical contact and, therefore, the degree of asexual intraspecies and interspecies adhesion in yeast. Such adhesion is controlled by a family of structurally related cell wall proteins encoded by theFLOgene family. As previously shown, the expression of specific members of theFLOgene family inSaccharomyces cerevisiaedramatically changes the coadhesion patterns between this yeast and other yeast species. Here, we use this differential aggregation mediated byFLOgenes as a model to assess the impact of physical contact between different yeast species on the relative fitness of these species in simplified ecosystems. The identity of theFLOgene has a marked effect on the persistence of specific non-Saccharomycesyeasts over the course of extended growth periods in batch cultures. Remarkably,FLO1andFLO5expression often result in opposite outcomes. The data provide clear evidence for the role of physical contact in multispecies yeast ecosystems and suggest thatFLOgene expression may be a major factor in such interactions.IMPORTANCEThe impact of direct (physical) versus indirect (metabolic) interactions between different yeast species has attracted significant research interest in recent years. This is due to the growing interest in the use of multispecies consortia in bioprocesses of industrial relevance and the relevance of interspecies interactions in establishing stable synthetic ecosystems. Compartment bioreactors have traditionally been used in this regard but suffer from numerous limitations. Here, we provide independent evidence for the importance of physical contact by using a genetic system, based on theFLOgene family, to modify the degree of physical contact and, therefore, the degree of asexual intraspecies and interspecies adhesion in yeast. Our results show that interspecies contact significantly impacts population dynamics and the survival of individual species. Remarkably, different members of theFLOgene family often lead to very different population outcomes, further suggesting thatFLOgene expression may be a major factor in such interactions.

scholarly journals Using the intrinsic growth rate of the mosquito population improves spatio-temporal dengue risk estimation

Acta Tropica ◽  
2020 ◽  
Vol 208 ◽  
pp. 105519
Author(s):  
Luigi Sedda ◽  
Benjamín M. Taylor ◽  
Alvaro E. Eiras ◽  
João Trindade Marques ◽  
Rod J. Dillon
Keyword(s):  
Growth Rate ◽  
Risk Estimation ◽  
Mosquito Population ◽  
Intrinsic Growth Rate ◽  
Spatio Temporal

scholarly journals The Genus Metschnikowia in Enology

2020 ◽  
Vol 8 (7) ◽  
pp. 1038 ◽  
Author(s):  
Javier Vicente ◽  
Javier Ruiz ◽  
Ignacio Belda ◽  
Iván Benito-Vázquez ◽  
Domingo Marquina ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Antimicrobial Activity ◽  
Yeast Species ◽  
Sensory Profile ◽  
Wine Yeasts ◽  
Wine Quality ◽  
Widespread Occurrence ◽  
Spoilage Yeasts ◽  
Potential Antimicrobial Activity ◽  
Wine Fermentations

Over the last decade, several non-Saccharomyces species have been used as an alternative yeast for producing wines with sensorial properties that are distinctive in comparison to those produced using only Saccharomyces cerevisiae as the classical inoculum. Among the non-Saccharomyces wine yeasts, Metschnikowia is one of the most investigated genera due to its widespread occurrence and its impact in winemaking, and it has been found in grapevine phyllospheres, fruit flies, grapes, and wine fermentations as being part of the resident microbiota of wineries and wine-making equipment. The versatility that allows some Metschnikowia species to be used for winemaking relies on an ability to grow in combination with other yeast species, such as S. cerevisiae, during the first stages of wine fermentation, thereby modulating the synthesis of secondary metabolites during fermentation in order to improve the sensory profile of the wine. Metschnikowia exerts a moderate fermentation power, some interesting enzymatic activities involving aromatic and color precursors, and potential antimicrobial activity against spoilage yeasts and fungi, resulting in this yeast being considered an interesting tool for use in the improvement of wine quality. The abovementioned properties have mostly been determined from studies on Metschnikowia pulcherrima wine strains. However, M. fructicola and M. viticola have also recently been studied for winemaking purposes.

A performance evaluation of surplus production models with time-varying intrinsic growth in dynamic ecosystems

2019 ◽  
Vol 76 (12) ◽  
pp. 2245-2255 ◽  
Author(s):  
Geneviève M. Nesslage ◽  
Michael J. Wilberg
Keyword(s):  
Growth Rate ◽  
Time Series ◽  
Survey Data ◽  
Atlantic Menhaden ◽  
Data Sets ◽  
Time Varying ◽  
Intrinsic Growth Rate ◽  
Surplus Production ◽  
Production Models ◽  
Exploitation Rate

We conducted a simulation study to evaluate performance of surplus production models (SPMs) with a time-varying intrinsic growth rate (SPMTVr) for stocks with predation-driven changes in productivity. Data sets were simulated using an age-structured, linked, predator–prey model of Atlantic menhaden (Brevoortia tyrannus), a forage fish native to the Northwest Atlantic, and Atlantic striped bass (Morone saxatilis), its primary predator, with differing time series of fishing mortality on both predator and prey. Simulations generated test data sets for Atlantic menhaden SPMs that included either a static or time-varying intrinsic growth rate parameter. The SPMTVr largely produced more accurate, less variable estimates of exploitation rate and biomass than models with static intrinsic growth. We also applied SPMTVr to empirical Atlantic menhaden catch and survey data for 1964–2016. The SPMTVr fit the survey data well, estimated an intrinsic growth rate time series that mirrored long-term juvenile survey trends, and produced biomass and exploitation rate trends that mirrored a statistical catch-at-age model. The SPMTVr estimated dynamic, maximum sustainable yield (MSY)-based reference points that reflected changing stock productivity.

scholarly journals Alterations in Yeast Species Composition of Uninoculated Wine Ferments by the Addition of Sulphur Dioxide

Fermentation ◽  
2020 ◽  
Vol 6 (2) ◽  
pp. 62 ◽  
Author(s):  
Kathleen Cuijvers ◽  
Steven Van Den Heuvel ◽  
Cristian Varela ◽  
Mark Rullo ◽  
Mark Solomon ◽  
...  
Keyword(s):  
Community Structure ◽  
Sulphur Dioxide ◽  
Yeast Species ◽  
Grape Juice ◽  
Wine Yeast ◽  
Aroma Compound ◽  
Microbial Composition ◽  
Yeast Community ◽  
Selection For ◽  
Saccharomyces Yeasts

Uninoculated wine fermentations are conducted by a consortium of wine yeast and bacteria that establish themselves either from the grape surface or from the winery environment. Of the additives that are commonly used by winemakers, sulphur dioxide (SO2) represents the main antimicrobial preservative and its use can have drastic effects on the microbial composition of the fermentation. To investigate the effect of SO2 on the resident yeast community of uninoculated ferments, Chardonnay grape juice from 2018 and 2019 was treated with a variety of SO2 concentrations ranging up to 100 mg/L and was then allowed to undergo fermentation, with the yeast community structure being assessed via high-throughput meta-barcoding (phylotyping). While the addition of SO2 was shown to select against the presence of many species of non-Saccharomyces yeasts, there was a clear and increasing selection for the species Hanseniaspora osmophila as concentrations of SO2 rose above 40 mg/L in fermentations from both vintages. Chemical analysis of the wines resulting from these treatments showed significant increases in acetate esters, and specifically the desirable aroma compound 2-phenylethyl acetate, that accompanied the increase in abundance of H. osmophila. The ability to modulate the yeast community structure of an uninoculated ferment and the resulting chemical composition of the final wine, as demonstrated in this study, represents an important tool for winemakers to begin to be able to influence the organoleptic profile of uninoculated wines.

scholarly journals Demographic aspects of Chrysomya megacephala (Diptera, Calliphoridae) adults maintained under experimental conditions: reproductive rate estimates

2006 ◽  
Vol 49 (3) ◽  
pp. 457-461 ◽  
Author(s):  
Marcelo Henrique de Carvalho ◽  
Claudio José Von Zuben
Keyword(s):  
Growth Rate ◽  
Life Expectancy ◽  
Reproductive Rate ◽  
Demographic Parameters ◽  
Intrinsic Growth Rate ◽  
Experimental Conditions ◽  
Chrysomya Megacephala ◽  
Finite Growth ◽  
Life Expectancy Estimate ◽  
Age Estimates

The objective of this work was to evaluate some aspects of the populational ecology of Chrysomya megacephala, analyzing demographic aspects of adults kept under experimental conditions. Cages of C. megacephala adults were prepared with four different larval densities (100, 200, 400 and 800). For each cage, two tables were made: one with demographic parameters for the life expectancy estimate at the initial age (e0), and another with the reproductive rate and average reproduction age estimates. Populational parameters such as the intrinsic growth rate (r) and the finite growth rate (lambda) were calculated as well.

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