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Current Biology : CB Oct 2021Many organisms consume pollen, yet mechanisms of its digestion remain a fundamental enigma in pollination biology, as pollen is protected by a recalcitrant outer shell....
Many organisms consume pollen, yet mechanisms of its digestion remain a fundamental enigma in pollination biology, as pollen is protected by a recalcitrant outer shell. Pollen is commonly found in floral nectar, as are nectar microbes, which are nearly ubiquitous among flowers. Nectar specialist bacteria, like Acinetobacter, can reach high densities (up to 10 cells/mL), despite the fact that floral nectar is nitrogen poor. Here, we show evidence that the genus Acinetobacter, prevalent nectar- and bee-associated bacteria, can induce pollen germination and bursting, gain access to protoplasm nutrients, and thereby grow to higher densities. Although induced germination had been suggested as a potential method in macroscopic pollen consumers, and fungal inhibition of pollen germination has been shown, direct biological induction of germination has not been empirically documented outside of plants.Acinetobacter pollinis SCC477 induced over 5× greater pollen germination and 20× greater pollen bursting than that of uninoculated pollen by 45 min. When provided with germinable pollen, A. pollinis stimulates protein release and grows to nearly twice the density compared to growth with ungerminable pollen, indicating that stimulation of germination benefits bacterial fitness. In contrast, a common nectar-inhabiting yeast (Metschnikowia) neither induced nor benefited from pollen germination. We conclude that Acinetobacter both specifically causes and benefits from inducing pollen germination and bursting. Further study of microbe-pollen interactions may inform many aspects of pollination ecology, including floral microbial ecology, pollinator nutrient acquisition from pollen, and cues of pollen germination for plant reproduction..
Topics: Animals; Bacteria; Bees; Flowers; Plant Nectar; Pollen; Pollination
PubMed: 34324834
DOI: 10.1016/j.cub.2021.07.016 -
Food Chemistry Feb 2022Black currants (Ribes nigrum) were fermented with Saccharomyces and non-Saccharomyces yeasts without added sugar to yield low-ethanol-content beverages. The effects of...
Comparison of volatile compounds and sensory profiles of alcoholic black currant (Ribes nigrum) beverages produced with Saccharomyces, Torulaspora, and Metschnikowia yeasts.
Black currants (Ribes nigrum) were fermented with Saccharomyces and non-Saccharomyces yeasts without added sugar to yield low-ethanol-content beverages. The effects of yeasts on the volatile compounds and sensory characteristics were analysed by HS-SPME-GC-MS, GC-O, and generic descriptive analysis. Ninety-eight volatile compounds were identified from the black currant juice and fermented beverages. Significant increases in the contents of esters (131 %), higher alcohols (391 %), and fatty acids (not present in juice sample) compared to initial juice were observed depending on the yeasts used. GC-O analysis revealed the higher impact of esters on the sensory properties of Saccharomyces bayanus-fermented beverage compared to the Torulaspora delbrueckii-fermented beverage. In the sensory evaluation, non-Saccharomyces yeasts resulted in a higher 'black currant odour'. However, all beverages were intensely sour, which can be a significant challenge in the development of alcoholic berry beverages.
Topics: Alcoholic Beverages; Fermentation; Metschnikowia; Ribes; Saccharomyces; Torulaspora; Wine; Yeasts
PubMed: 34520974
DOI: 10.1016/j.foodchem.2021.131049 -
Microorganisms Sep 2022Non-conventional yeasts (NCY) (i.e., non-) may be used as alternative starters to promote biodiversity and quality of fermented foods and beverages (e.g., wine, beer,...
BACKGROUND
Non-conventional yeasts (NCY) (i.e., non-) may be used as alternative starters to promote biodiversity and quality of fermented foods and beverages (e.g., wine, beer, bakery products).
METHODS
A total of 32 wine-associated yeasts (Campania region, Italy) were genetically identified and screened for decarboxylase activity and leavening ability. The best selected strains were used to study the leavening kinetics in model doughs (MDs). A commercial strain of was used as the control. The volatile organic profiles of the inoculated MDs were analyzed by solid phase microextraction/gas chromatography-mass spectrometry (SPME/GC-MS).
RESULTS
Most of strains belonged to the NCY species , , , , and , while a few strains were . Most strains of lacked decarboxylase activity and showed a high leaving activity after 24 h of incubation that was comparable to the strains. The selected strains generated a different flavor profile of the doughs compared to the strains. In particular, NCY reduced the fraction of aldehydes that were potentially involved in oxidative phenomena.
CONCLUSIONS
The use of NCY could be advantageous in the bakery industry, as they can provide greater diversity than -based products, and may be useful in reducing and avoiding yeast intolerance.
PubMed: 36144451
DOI: 10.3390/microorganisms10091849 -
Microorganisms Jun 2022The total diversity of bacterial and fungal communities associated with the phyllosphere (fruits and leaves) of the 'Williams' pear variety was analyzed in two...
The total diversity of bacterial and fungal communities associated with the phyllosphere (fruits and leaves) of the 'Williams' pear variety was analyzed in two phenological stages during fruit development and maturation. The antagonistic potential of autochthonous bacterial and yeast isolates against phytopathogenic fungi was also evaluated. A metabarcoding approach revealed , , , , and as dominant bacterial constituents of the pear phyllosphere, whilst most abundant among the fungal representatives identified were , , , , and . The traditional culturable approach revealed that the genus with , , and was most prevalent. The most frequently cultivated fungal representatives belonged to the genus with six identified species. A broad range of the antagonistic activity was detected for the and yeasts, significantly affecting the growth of many fungal isolates in the range of 53-70%. was the most susceptible fungal isolate. The autochthonous antagonistic yeasts and might be powerful biological control agents of postharvest diseases caused by spp. and common pathogens like , , , and .
PubMed: 35889000
DOI: 10.3390/microorganisms10071282 -
Journal of Food Science and Technology Nov 2019Non- yeasts are metabolically active during grape must fermentations and can contribute with enzymes and metabolites to enhance the complexity and to define the final...
Non- yeasts are metabolically active during grape must fermentations and can contribute with enzymes and metabolites to enhance the complexity and to define the final wine aroma. Nowadays, the use of non- yeasts in combination with is a state-of-the art strategy to improve wine composition and/or wine sensory properties. The present paper deals with the new yeast strains of and , that were selected as representatives of the yeast microbiota isolated from grapes and grape juice of Aglianico cultivar. was utilized both as single strain starter and in combination with in experimental fermentations of Aglianico must. The dynamic of yeast populations was evaluated during the fermentation process analyzing the wine volatile compounds profile. The volatile compounds were identified by SPME-GC/MS. The results, showed that the multiple indigenous yeast starter was able to modulate the volatile compounds profiles and improve the aromatic complexity of wine, with a higher content of esters and terpenes.
PubMed: 31741522
DOI: 10.1007/s13197-019-03970-9 -
Heliyon Apr 2024, a novel endophytic yeast strain isolated from calyx, possesses strong antimicrobial activity. We investigated its potential use as an environmentally safe food...
, a novel endophytic yeast strain isolated from calyx, possesses strong antimicrobial activity. We investigated its potential use as an environmentally safe food biocontrol agent through genomics, transcriptomics, and metabolomics. Secondary metabolites were isolated from , followed by chemical structure elucidation, gene cluster identification, and RNA sequencing. Pulcherrimin was isolated using 2 M NaOH, its structure was confirmed, and the yield was quantified. Biocontrol efficacy of on persimmon fruits and calyx was evaluated by assessing lesion diameter and disease incidence. Following compounds were isolated from co-culture with and : fusaric acid, benzoic acid, benzeneacetic acid, 4-hydroxybenzeneacetic acid, 4-(-2-hydoxyethyl)-benzoic acid, cyclo (Leu-Leu), benzenemethanol, 4-hydroxy-benzaldehide, 2-hydroxy-4-methoxy-benzoic acid, 4-hydroxy-benzoic acid, lumichrome, heptadecanoic acid, and nonadecanoic acid. Exposing to different growth media conditions (with or without sugar) resulted in the isolation of five compounds: Tyrosol, Cyclo (Pro-Val), cyclo(L-Pro-L-Tyr), cyclo(Leu-Leu), and cyclo(l-tyrosilylicine). Differentially expressed gene analysis revealed 3264 genes that were significantly expressed (fold change ≥2 and p-value ≤0.05) during growth in different media, of which only 270 (8.27%) showed altered expression in all sample combinations with Luria-Bertani Agar as control. Minimal media with ferric ions and tween-80 triggered the most gene expression changes, with the highest levels of gene expression and pulcherrimin yield (262.166 mg/L) among all media treatments. also produced a higher amount of pulcherrimin (209.733 mg/L) than (152.8 mg/L). inhibited the growth of in persimmon fruit and calyx. Toxicity evaluation of extracts showed no harmful effects on the liver and mitochondria of zebrafish, and no potential risk of cardiotoxicity in hERG-HEK293 cell lines. Thus, can be commercialized as a potent and safe biocontrol agent for preserving food products.
PubMed: 38571591
DOI: 10.1016/j.heliyon.2024.e28464 -
Metabolites Aug 2020Yeasts constitute a dietary source for the spotted wing drosophila (SWD) and produce compounds that attract these flies. The study of the chemical composition of the...
Yeasts constitute a dietary source for the spotted wing drosophila (SWD) and produce compounds that attract these flies. The study of the chemical composition of the yeast communities associated with SWD should therefore help to understand the relationship between the biology of the insect and the yeast's metabolism. In the present study, the lipidome of five yeast species isolated from grapes infested by SWD (three strains, sp., , and ) and a laboratory strain of was explored using an untargeted approach. Additionally, the lipid profile of two species, and , which were reported to elicit different responses on SWD flies based on feeding and behavioral trials, was compared with a chemical enrichment approach. Overall, 171 lipids were annotated. The yeast species could be distinguished from each other based on their lipid profile, except for the three strains of which were very similar to each other. The chemical enrichment analysis emphasized diversities between and , that could not be detected based on their global lipid profile. The information concerning differences between species in their lipidome may be of interest to future entomological studies concerning the yeast-insect interaction and could help to explain the responses of SWD to diverse yeast species.
PubMed: 32872268
DOI: 10.3390/metabo10090352 -
Foods (Basel, Switzerland) Aug 2020The influence of fruit varieties on yeast ecology during spontaneous plum mash fermentation was investigated. Yeast colonies were isolated from mashes obtained from four...
The influence of fruit varieties on yeast ecology during spontaneous plum mash fermentation was investigated. Yeast colonies were isolated from mashes obtained from four plum varieties throughout fermentation in laboratory conditions during two consecutive years. The yeast strains were differentiated by random amplification of polymorphic DNA (RAPD-PCR) and identified by the 26S rDNA D1/D2 sequence analysis. , spp. and were the dominant yeasts during the early stages of plum mash fermentation, while the middle and end phases were dominated by . The strains of , , , and were also detected in fermenting plum mashes. sp. M1, H1 and H2 strains were detected in all samples, irrespective of the tested variety and year. Investigation of the impact of individual yeast strains on the production of volatile compounds showed the potential possibility of using them as starter cultures.
PubMed: 32759797
DOI: 10.3390/foods9081054 -
Applied and Environmental Microbiology Nov 2019Yeasts form mutualistic interactions with insects. Hallmarks of this interaction include provision of essential nutrients, while insects facilitate yeast dispersal and...
Yeasts form mutualistic interactions with insects. Hallmarks of this interaction include provision of essential nutrients, while insects facilitate yeast dispersal and growth on plant substrates. A phylogenetically ancient chemical dialogue coordinates this interaction, where the vocabulary, the volatile chemicals that mediate the insect response, remains largely unknown. Here, we used gas chromatography-mass spectrometry, followed by hierarchical cluster and orthogonal partial least-squares discriminant analyses, to profile the volatomes of six spp., , and brewer's yeast (). The yeasts, which are all found in association with insects feeding on foliage or fruit, emit characteristic, species-specific volatile blends that reflect the phylogenetic context. Species specificity of these volatome profiles aligned with differential feeding of cotton leafworm () larvae on these yeasts. Bioactivity correlates with yeast ecology; phylloplane species elicited a stronger response than fruit yeasts, and larval discrimination may provide a mechanism for establishment of insect-yeast associations. The yeast volatomes contained a suite of insect attractants known from plant and especially floral headspace, including ()-hexenyl acetate, ethyl (2,4)-deca-2,4-dienoate (pear ester), (3)-4,8-dimethylnona-1,3,7-triene (DMNT), linalool, α-terpineol, β-myrcene, or (,)-α-farnesene. A wide overlap of yeast and plant volatiles, notably floral scents, further emphasizes the prominent role of yeasts in plant-microbe-insect relationships, including pollination. The knowledge of insect-yeast interactions can be readily brought to practical application, as live yeasts or yeast metabolites mediating insect attraction provide an ample toolbox for the development of sustainable insect management. Yeasts interface insect herbivores with their food plants. Communication depends on volatile metabolites, and decoding this chemical dialogue is key to understanding the ecology of insect-yeast interactions. This study explores the volatomes of eight yeast species which have been isolated from foliage, from flowers or fruit, and from plant-feeding insects. These yeasts each release a rich bouquet of volatile metabolites, including a suite of known insect attractants from plant and floral scent. This overlap underlines the phylogenetic dimension of insect-yeast associations, which according to the fossil record long predate the appearance of flowering plants. Volatome composition is characteristic for each species, aligns with yeast taxonomy, and is further reflected by a differential behavioral response of cotton leafworm larvae, which naturally feed on foliage of a wide spectrum of broad-leaved plants. Larval discrimination may establish and maintain associations with yeasts and is also a substrate for designing sustainable insect management techniques.
Topics: Acyclic Monoterpenes; Animals; Cryptococcus; Cyclohexane Monoterpenes; Flowers; Fruit; Gas Chromatography-Mass Spectrometry; Herbivory; Host Microbial Interactions; Insecta; Larva; Metabolome; Metschnikowia; Odorants; Pheromones; Phylogeny; Saccharomyces cerevisiae; Smell; Spodoptera; Volatile Organic Compounds; Yeasts
PubMed: 31444202
DOI: 10.1128/AEM.01761-19 -
Nitrogen Preferences during Alcoholic Fermentation of Different Non- Yeasts of Oenological Interest.Microorganisms Jan 2020Non- yeasts have long been considered spoilage microorganisms. Currently, oenological interest in those species is increasing, mostly due to their positive contribution...
Non- yeasts have long been considered spoilage microorganisms. Currently, oenological interest in those species is increasing, mostly due to their positive contribution to wine quality. In this work, the fermentative capacity and nitrogen consumption of several non- wine yeast ( and ) were analyzed. For this purpose, synthetic must with three different nitrogen compositions was used: a mixture of amino acids and ammonium, only organic or inorganic nitrogen. The fermentation kinetics, nitrogen consumption, and yeast growth were measured over time. Our results showed that the good fermentative strains, and , had high similarities with in terms of growth, fermentation profile, and nitrogen assimilation preferences, although presented an impaired behavior when only amino acids or ammonia were used, being strain-specific. was the non- strain least affected by the nitrogen composition of the medium. The other two poor fermentative strains, and , behaved similarly regarding amino acid uptake, which occurred earlier than that of the good fermentative species in the absence of ammonia. The results obtained in single non- fermentations highlighted the importance of controlling nitrogen requirements of the wine yeasts, mainly in sequential fermentations, in order to manage a proper nitrogen supplementation, when needed.
PubMed: 31979188
DOI: 10.3390/microorganisms8020157