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Frontiers in Microbiology 2023Finding alternatives to the use of chemical inputs to preserve the sanitary and organoleptic quality of food and beverages is essential to meet public health... (Review)
Review
Finding alternatives to the use of chemical inputs to preserve the sanitary and organoleptic quality of food and beverages is essential to meet public health requirements and consumer preferences. In oenology, numerous manufacturers already offer a diverse range of bio-protection yeasts to protect must against microbiological alterations and therefore limit or eliminate sulphites during winemaking. Bio-protection involves selecting non- yeasts belonging to different genera and species to induce negative interactions with indigenous microorganisms, thereby limiting their development and their impact on the matrix. Although the effectiveness of bio-protection in the winemaking industry has been reported in numerous journals, the underlying mechanisms are not yet well understood. The aim of this review is to examine the current state of the art of field trials and laboratory studies that demonstrate the effects of using yeasts for bio-protection, as well as the interaction mechanisms that may be responsible for these effects. It focuses on the yeast , particularly recommended for the bio-protection of grape musts.
PubMed: 37664122
DOI: 10.3389/fmicb.2023.1252973 -
Microbial Biotechnology Sep 2013Competition between microbial species is a product of, yet can lead to a reduction in, the microbial diversity of specific habitats. Microbial habitats can resemble... (Review)
Review
Competition between microbial species is a product of, yet can lead to a reduction in, the microbial diversity of specific habitats. Microbial habitats can resemble ecological battlefields where microbial cells struggle to dominate and/or annihilate each other and we explore the hypothesis that (like plant weeds) some microbes are genetically hard-wired to behave in a vigorous and ecologically aggressive manner. These 'microbial weeds' are able to dominate the communities that develop in fertile but uncolonized--or at least partially vacant--habitats via traits enabling them to out-grow competitors; robust tolerances to habitat-relevant stress parameters and highly efficient energy-generation systems; avoidance of or resistance to viral infection, predation and grazers; potent antimicrobial systems; and exceptional abilities to sequester and store resources. In addition, those associated with nutritionally complex habitats are extraordinarily versatile in their utilization of diverse substrates. Weed species typically deploy multiple types of antimicrobial including toxins; volatile organic compounds that act as either hydrophobic or highly chaotropic stressors; biosurfactants; organic acids; and moderately chaotropic solutes that are produced in bulk quantities (e.g. acetone, ethanol). Whereas ability to dominate communities is habitat-specific we suggest that some microbial species are archetypal weeds including generalists such as: Pichia anomala, Acinetobacter spp. and Pseudomonas putida; specialists such as Dunaliella salina, Saccharomyces cerevisiae, Lactobacillus spp. and other lactic acid bacteria; freshwater autotrophs Gonyostomum semen and Microcystis aeruginosa; obligate anaerobes such as Clostridium acetobutylicum; facultative pathogens such as Rhodotorula mucilaginosa, Pantoea ananatis and Pseudomonas aeruginosa; and other extremotolerant and extremophilic microbes such as Aspergillus spp., Salinibacter ruber and Haloquadratum walsbyi. Some microbes, such as Escherichia coli, Mycobacterium smegmatis and Pseudoxylaria spp., exhibit characteristics of both weed and non-weed species. We propose that the concept of nonweeds represents a 'dustbin' group that includes species such as Synodropsis spp., Polypaecilum pisce, Metschnikowia orientalis, Salmonella spp., and Caulobacter crescentus. We show that microbial weeds are conceptually distinct from plant weeds, microbial copiotrophs, r-strategists, and other ecophysiological groups of microorganism. Microbial weed species are unlikely to emerge from stationary-phase or other types of closed communities; it is open habitats that select for weed phenotypes. Specific characteristics that are common to diverse types of open habitat are identified, and implications of weed biology and open-habitat ecology are discussed in the context of further studies needed in the fields of environmental and applied microbiology.
Topics: Biota; Environmental Microbiology; Microbial Interactions; Selection, Genetic
PubMed: 23336673
DOI: 10.1111/1751-7915.12027 -
FEMS Microbiology Ecology Jul 2023Bee-fungus associations are common, and while most studies focus on entomopathogens, emerging evidence suggests that bees associate with a variety of symbiotic fungi... (Review)
Review
Bee-fungus associations are common, and while most studies focus on entomopathogens, emerging evidence suggests that bees associate with a variety of symbiotic fungi that can influence bee behavior and health. Here, we review nonpathogenic fungal taxa associated with different bee species and bee-related habitats. We synthesize results of studies examining fungal effects on bee behavior, development, survival, and fitness. We find that fungal communities differ across habitats, with some groups restricted mostly to flowers (Metschnikowia), while others are present almost exclusively in stored provisions (Zygosaccharomyces). Starmerella yeasts are found in multiple habitats in association with many bee species. Bee species differ widely in the abundance and identity of fungi hosted. Functional studies suggest that yeasts affect bee foraging, development, and pathogen interactions, though few bee and fungal taxa have been examined in this context. Rarely, fungi are obligately beneficial symbionts of bees, whereas most are facultative bee associates with unknown or ecologically contextual effects. Fungicides can reduce fungal abundance and alter fungal communities associated with bees, potentially disrupting bee-fungi associations. We recommend that future study focus on fungi associated with non-honeybee species and examine multiple bee life stages to document fungal composition, abundance, and mechanistic effects on bees.
Topics: Bees; Animals; Fungicides, Industrial; Ecosystem; Mycobiome; Porifera; Metschnikowia; Fungi
PubMed: 37422442
DOI: 10.1093/femsec/fiad077 -
Foods (Basel, Switzerland) Nov 2022On the one hand, the species Lachancea thermotolerans is known for its high genetic diversity, allowing for the existence of strains that produce high concentrations of...
On the one hand, the species Lachancea thermotolerans is known for its high genetic diversity, allowing for the existence of strains that produce high concentrations of lactic acid. In contrast, the species Metschnikowia pulcherrima is renowned for its high enzymatic activity capable of producing aromatic esters during fermentation. By enhancing acidity and boosting the concentration of aromatic compounds, both species are currently used to enhance the organoleptic profile of wines. In this regard, ternary fermentations with M. pulcherrima and L. thermotolerans were carried out and the wines produced were further analysed with GC-FID, FTIR, and UV-Vis spectrophotometry. The outcomes showed that the species M. pulcherrima favored an increase in ethyl lactate (between 37 and 41 mg/L) along with an increased concentration of 2-phenylethyl alcohol (between 30 and 35 mg/L), whereas the species L. thermotolerans was able to produce 1 g/L of lactic acid in ternary fermentations. Additionally, pH levels were slightly lower in these fermentations and the color of the white wines produced showed less chemical oxidation as hue values were lower than the control. Finally, the ternary fermentations of L. thermotolerans and M. pulcherrima had higher overall rating in the tasting. In conclusion, ternary fermentations involving these two non-Saccharomyces species are suggested as a substitute for spontaneous fermentations in the production of wines from neutral varieties to express freshness more vividly. This biotechnology may be further favored by the possibility of applying emerging technologies for the removal of microorganisms in grapes and musts.
PubMed: 36429326
DOI: 10.3390/foods11223734 -
International Journal of Molecular... Jan 2021The surfaces of grapes are covered by different yeast species that are important in the first stages of the fermentation process. In recent years, non- yeasts such as ,... (Review)
Review
The surfaces of grapes are covered by different yeast species that are important in the first stages of the fermentation process. In recent years, non- yeasts such as , , , and have become popular with regard to winemaking and improved wine quality. For that reason, several manufacturers started to offer commercially available strains of these non- species. stands out, mainly due to its contribution to wine aroma, glycerol, ethanol yield, and killer factor. The metabolism of the yeast allows it to increase volatile molecules such as esters and varietal thiols (aroma-active compounds), which increase the quality of specific varietal wines or neutral ones. It is considered a low- or non-fermentative yeast, so subsequent inoculation of a more fermentative yeast such as is indispensable to achieve a proper fermented alcohol. The impact of is not limited to the grape wine industry; it has also been successfully employed in beer, cider, durian, and tequila fermentation, among others, acting as a promising tool in those fermentation processes. Although no species other than is available in the regular market, several recent scientific studies show interesting improvements in some wine quality parameters such as aroma, polysaccharides, acid management, and color stability. This could motivate yeast manufacturers to develop products based on those species in the near future.
Topics: Bioengineering; Ecology; Fermentation; Food Quality; Industrial Microbiology; Pichia; Vitis; Wine
PubMed: 33530422
DOI: 10.3390/ijms22031196 -
Frontiers in Bioscience (Elite Edition) Jan 2023The vineyard is a great reservoir of autochthonous yeast strains whose composition is defined by different regional (edaphology, orography or climatology) and...
BACKGROUND
The vineyard is a great reservoir of autochthonous yeast strains whose composition is defined by different regional (edaphology, orography or climatology) and anthropological factors (cultivation systems or cultural practices). Most of this yeast diversity corresponds to non- strains, some of which have potential use in winemaking.
METHODS
The oenological potential of 29 different native non- strains belonging to 4 species (, , and spp.) was evaluated, using the autochthonous XG3 strain as a control. Microfermentations with pure culture of each strain were performed in duplicate and the basic parameters and major volatiles of wines were analysed following official methodology. The best strain within each species was selected using a quantification matrix including the relevant oenological characteristics.
RESULTS
The fermentative ability of non- was lower than in all cases, but with differences among species. and showed higher fermentation rates than , whereas spp. presented a low fermentative power. At chemical level all non- strains reduced the alcoholic content, the higher alcohols and the volatile acidity of wines and increased the content of glycerol, with differences among strains within a given species. and increased the total acidity of wines. The latter and spp. strains produced lactic acid, which decreased the wine pH in the case of . According to their oenological traits the best rated strains of each species were Lt93, Td315, Mf278 and Sb474. In addition, the data obtained in pure fermentations were correlated to those chemical and aromatic compounds obtained with these non- strains in sequential fermentations.
CONCLUSIONS
Autochthonous strains of non- yeast species contribute distinctive chemical characteristics to the wines. The correlations observed between wines fermented with the different non- indigenous strains in pure and sequential fermentations suggest that their contribution to wine properties remains stable regardless of must composition or winemaking techniques.
Topics: Saccharomyces cerevisiae; Vitis; Wine; Glycerol
PubMed: 36959102
DOI: 10.31083/j.fbe1501001 -
Molecules (Basel, Switzerland) Jan 2021Wine fermentation processes are driven by complex microbial systems, which comprise eukaryotic and prokaryotic microorganisms that participate in several biochemical... (Review)
Review
Wine fermentation processes are driven by complex microbial systems, which comprise eukaryotic and prokaryotic microorganisms that participate in several biochemical interactions with the must and wine chemicals and modulate the organoleptic properties of wine. Among these, yeasts play a fundamental role, since they carry out the alcoholic fermentation (AF), converting sugars to ethanol and CO together with a wide range of volatile organic compounds. The contribution of , the reference organism associated with AF, has been extensively studied. However, in the last decade, selected strains received considerable commercial and oenological interest due to their specific pro-technological aptitudes and the positive influence on sensory quality. This review aims to highlight the inter-specific variability within the heterogeneous class of non- in terms of synthesis and release of volatile organic compounds during controlled AF in wine. In particular, we reported findings on the presence of model non- organisms, including spp. and , in combination with . The evidence is discussed from both basic and applicative scientific perspective. In particular, the oenological significance in different kind of wines has been underlined.
Topics: Fermentation; Hanseniaspora; Metschnikowia; Odorants; Pichia; Saccharomycetales; Torulaspora; Volatile Organic Compounds; Wine
PubMed: 33530641
DOI: 10.3390/molecules26030644 -
Molecules (Basel, Switzerland) Mar 2022Pulcherrimin is a secondary metabolite of yeasts belonging to the clade, and pulcherrimin formation is responsible for the antimicrobial action of its producers....
Pulcherrimin is a secondary metabolite of yeasts belonging to the clade, and pulcherrimin formation is responsible for the antimicrobial action of its producers. Understanding the environmental function of this metabolite can provide insight into various microbial interactions and enables the efficient development of new effective bioproducts and methods. In this study, we evaluated the antimicrobial and antiadhesive action of yeast pulcherrimin, as well as its protective properties under selected stressful conditions. Classical microbiological plate methods, microscopy, and physico-chemical testing were used. The results show that pure pulcherrimin does not have antimicrobial properties, but its unique hydrophilic nature may hinder the adhesion of hydrophilic bacterial cells to abiotic surfaces. Pulcherrimin also proved to be a good cell protectant against UV-C radiation at both high and low temperatures.
Topics: Anti-Bacterial Agents; Bone Plates; Cold Temperature; Microbial Interactions; Microbiological Techniques
PubMed: 35335219
DOI: 10.3390/molecules27061855 -
PloS One 2021Currently, one of the most important challenges is to provide sufficient and affordable food and energy for a fast-growing world population, alongside preserving natural...
Inoculation of pear flowers with Metschnikowia reukaufii and Acinetobacter nectaris enhances attraction of honeybees and hoverflies, but does not increase fruit and seed set.
Currently, one of the most important challenges is to provide sufficient and affordable food and energy for a fast-growing world population, alongside preserving natural habitats and maintaining biodiversity. About 35% of the global food production depends on animals for pollination. In recent years, an alarming worldwide decline in pollinators has been reported, putting our food production under additional pressure. Therefore, there is an urgent need to find sustainable ways to ensure this crucial ecosystem service. Recent studies have shown that floral nectar is generally colonized by microorganisms, specifically yeasts and bacteria, which may alter nectar chemistry and enhance attraction of pollinators. In this study, we investigated changes in pollinator foraging behavior and pollination success in European pear (Pyrus communis L.) cultivars 'Regal Red' and 'Sweet Sensation' (red sports of 'Doyenné de Comice') after flower inoculation with the typical nectar-inhabiting microorganisms Metschnikowia reukaufii and Acinetobacter nectaris, and a combination of both. Pollination success was monitored by measuring the number of flower visits, fruit set and seed set in two consecutive years, 2019 and 2020. Results revealed that application of a mixture of M. reukaufii and A. nectaris resulted in significantly higher visitation rates of honeybees and hoverflies. By contrast, no effects on flower visits were found when yeasts and bacteria were applied separately. Fruit set and seed set were not significantly affected by any of the inoculation treatments. The only factors affecting fruit set were initial number of flower clusters on the trees and the year. The absence of treatment effects can most likely be attributed to the fact that pollination was not a limiting factor for fruit set in our experiments. Altogether, our results show that inoculation of flowers with nectar microbes can modify pollinator foraging patterns, but did not lead to increased pollination success under the conditions tested.
Topics: Animals; Bees; Flowers; Fruit; Plant Nectar; Pollination; Pyrus
PubMed: 33886638
DOI: 10.1371/journal.pone.0250203 -
Ecology and Evolution Dec 2022Host immune traits arise from both genetic and environmental sources of variation. When immune traits have a strong genetic basis, the presence and severity of disease...
Host immune traits arise from both genetic and environmental sources of variation. When immune traits have a strong genetic basis, the presence and severity of disease in a population may influence the distribution of those traits. Our study addressed how two immune-related traits (gut penetrability and the hemocyte response) are shaped by genetic and environmental sources of variation, and how the presence of a virulent disease altered the relative frequency of these traits in natural populations. hosts were sampled from five Indiana lakes between June and December 2017 before and during epidemics of their fungal pathogen, . Collected were experimentally exposed to and assayed for their gut penetrability, hemocyte response, and multi-locus genotype. Mixed-effects models were constructed to partition variance in immune traits between genetic and environmental sources. We then isolated the genetic sources to produce genotype-specific estimates of immune traits for each multi-locus genotype. Finally, we assessed the relative frequency and dynamics of genotypes during epidemics and asked whether genotypes with more robust immune responses increased in frequency during epidemics. Although genotype was an important source of variation for both gut penetrability and the hemocyte response, environmental factors (e.g., resource availability, prevalence, and co-infection) still explained a large portion of observed variation, suggesting a high degree of flexibility in immune traits. Additionally, no significant associations were detected between a genotype's immune traits and its frequency in a population. Our study highlights the power of variance partitioning in understanding the factors driving variation in traits and motivates further research on immunological flexibility and the ecological drivers of immune variation.
PubMed: 36545366
DOI: 10.1002/ece3.9640