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Frontiers in Microbiology 2023Our recent research study focused on Miang fermentation revealed that tannin-tolerant yeasts and bacteria play vital roles in the Miang production process. A high...
Our recent research study focused on Miang fermentation revealed that tannin-tolerant yeasts and bacteria play vital roles in the Miang production process. A high proportion of yeast species are associated with plants, insects, or both, and nectar is one of the unexplored sources of yeast biodiversity. Therefore, this study aimed to isolate and identify yeasts of tea flowers of var. and to investigate their tannin tolerance, which is a property essential to Miang production processes. A total of 82 yeasts were recovered from a total of 53 flower samples in Northern Thailand. It was found that two and eight yeast strains were distinct from all other known species within the genera and , respectively. These yeast strains were described as three new species, namely, , , and . The identification of these species was based on phenotypic (morphological, biochemical, and physiological characteristics) and phylogenetic analyses of a combination of the internal transcribed spacer (ITS) regions and the D1/D2 domains of the large subunit (LSU) ribosomal RNA gene. The yeast diversity in tea flowers acquired from Chiang Mai, Lampang, and Nan provinces had a positive correlation with those acquired from Phayao, Chiang Rai, and Phrae, respectively. , , and were the species uniquely found in tea flowers collected from Nan and Phrae, Chiang Mai, and Lampang provinces, respectively. Some of the tannin-tolerant and/or tannase-producing yeasts were associated with yeasts in the commercial Miang process and those found during Miang production, i.e., , , , , , , , and . In conclusion, these studies suggest that floral nectar could support the formation of yeast communities that are beneficial for Miang production.
PubMed: 36876082
DOI: 10.3389/fmicb.2023.1043430 -
Microbial Biotechnology May 2023The recent introduction of non-conventional yeast species as companion wine starters has prompted a growing interest in microbial interactions during wine fermentation....
The recent introduction of non-conventional yeast species as companion wine starters has prompted a growing interest in microbial interactions during wine fermentation. There is evidence of interactions through interference and exploitation competition, as well as interactions depending on physical contact. Furthermore, the results of some transcriptomic analyses suggest interspecific communication, but the molecules or biological structures involved in recognition are not well understood. In this work, we explored extracellular vesicles (EVs) as possible mediators of interspecific communication between wine yeasts. The transcriptomic response of Saccharomyces cerevisiae after 3 h of contact with a fraction enriched in EVs of Metschnikowia pulcherrima was compared with that induced by active M. pulcherrima cells. Interestingly, there is a high level of overlap between the transcriptomic profiles of yeast cells challenged by either M. pulcherrima whole cells or the EV-enriched fraction. The results indicate an upregulation of yeast metabolism in response to competing species (in line with previous results). This finding points to the presence of a signal, in the EV-enriched fraction, that can be perceived by the yeast cells as a cue for the presence of competitors, even in the absence of metabolically active cells of the other species.
Topics: Saccharomyces cerevisiae; Wine; Coculture Techniques; Fermentation; Extracellular Vesicles
PubMed: 36840970
DOI: 10.1111/1751-7915.14240 -
Microorganisms Feb 2023Four non-conventional oleaginous and pigmented yeast strains of , , , and were used in this study. Complex yeast extracts were prepared and tested for biological...
Four non-conventional oleaginous and pigmented yeast strains of , , , and were used in this study. Complex yeast extracts were prepared and tested for biological activity, safety, and effect on human health. In this paper, we measured the antioxidant activity and antimicrobial effect of yeast biomass as a whole and their extracts to compare the influence of carotenoids and other bioactive substances in the studied biomass. All yeast extracts exhibited a significant dose-dependent antimicrobial effect against both G+ and G- bacteria and had a strong antioxidant effect. No cytotoxicity in the mouse melanoma B16F1 cell line was found in concentrations up to 20% of rehydrated biomass in cell medium. All of the extracts were cytotoxic at a concentration of 5 mg of extract/g of dry biomass. All the pigmented yeast extracts showed some positive results for apoptosis of murine melanoma cell lines and are therefore strong candidates positively effect human health. Red yeast cell biomass is a prospective material with many attractive biological functions and can be used in the food industry, as a pharmaceutical material, or in the feed industry.
PubMed: 36838460
DOI: 10.3390/microorganisms11020492 -
Foods (Basel, Switzerland) Feb 2023Although bioprotection is now recognised as an alternative to SO for limiting microbial spoilage, it does not guarantee protection against oxidation. This limits its...
Although bioprotection is now recognised as an alternative to SO for limiting microbial spoilage, it does not guarantee protection against oxidation. This limits its application, more specifically for rosé winemaking. Oenological tannins present antioxidant properties, which could represent an interesting alternative to SO to protect must and wines against oxidation. A combination of the inoculation of a bioprotectant yeast strain and the addition of oenological tannins was tested to eliminate sulfites during the pre-fermentative step of rosé winemaking. In this experiment carried out in a winery, two oenological tannins were compared: quebracho and gall nut tannins. The antioxidant efficiency of tannins was compared to that of SO. Colorimetric assays associated with chemical analyses of anthocyanins and phenolic compounds confirmed that the use of bioprotection alone did not protect the wine from oxidation. An addition of oenological tannins on musts stabilized the colour of bioprotected rosé wine in a similar way that SO addition did. Quebracho tannins appeared more efficient than gall nut tannins. The colour differences observed cannot be explained either by the concentration or forms of anthocyanins. However, the addition of tannins led to better protection of oxidation-sensitive phenolic compounds comparable to that obtained with the addition of sulfites.
PubMed: 36832809
DOI: 10.3390/foods12040735 -
Antioxidants (Basel, Switzerland) Feb 2023Catarratto is one of the most widely cultivated grape varieties in Sicily. It is an indigenous non-aromatic white grape variety. Despite its widespread use in...
Catarratto is one of the most widely cultivated grape varieties in Sicily. It is an indigenous non-aromatic white grape variety. Despite its widespread use in winemaking, knowledge of the aroma and chemical and microbiological properties of Catarratto wines is quite limited. The influence of combined with on the aromatic expression of Catarratto wines was investigated with and without the addition of glutathione-rich inactivated yeast. The substance is a natural specific inactivated yeast with a guaranteed glutathione level used to limit oxidative processes. The aromatic profiles of the final wines were determined through analysis of the volatile organic compounds using a solid-phase microextraction technique that identified 26 aromatic compounds. The addition of in combination with the natural antioxidant undoubtedly increased the aromatic complexity of the wines. Dodecanal was exclusively detected in the wines processed with glutathione-rich inactivated yeasts. Furthermore, the presence of this natural antioxidant increased the concentration of six esters above the perception threshold. Sensory analysis was also performed with a panel of trained judges who confirmed the aromatic differences among the wines. These results suggest the suitability of glutathione-rich inactivated yeasts for determining the oxidative stability of Catarratto wines, thus preserving its aromatic compounds and colour.
PubMed: 36829997
DOI: 10.3390/antiox12020439 -
Biology Jan 2023Geographic location and, particularly, soil and climate exert influence on the typicality of a wine from a specific region, which is often justified by the , and these...
Geographic location and, particularly, soil and climate exert influence on the typicality of a wine from a specific region, which is often justified by the , and these factors also influence the epiphytic flora associated with the surface of the grape berries. In the present study, the microbiome associated with the surface of berries obtained from ten vineyards of the variety located in different geographical locations in mainland Portugal was determined and analyzed. The removal of microbial flora from the surface of the berries was carried out by washing and sonication, after which the extraction and purification of the respective DNA was carried out. High-throughput short amplicon sequencing of the fungal ITS region and the bacterial 16S region was performed, allowing for the determination of the microbial consortium associated with wine grapes. Analysis of α-diversity demonstrated that parcels from the Monção and Melgaço sub-region present a significantly ( < 0.05) lower fungal diversity and species richness when compared to the plots analyzed from other regions/sub-regions. The ubiquitous presence of spp., a yeast with enologic potential interest in all parcels from Monção and Melgaço, was also observed.
PubMed: 36829425
DOI: 10.3390/biology12020146 -
Food Technology and Biotechnology Dec 2022Wine yeasts are a heterogeneous microbial group with high enzymatic potential that makes them a useful tool in winemaking. With a better understanding of their...
RESEARCH BACKGROUND
Wine yeasts are a heterogeneous microbial group with high enzymatic potential that makes them a useful tool in winemaking. With a better understanding of their oenological properties, selection procedures can be optimised to obtain more efficient strains. The present study aims to isolate and select yeasts from wine grape surface by studying their production of enzymes that hydrolyse plant cell wall polymers and by linking them to different technological parameters and antioxidant activity of wines.
EXPERIMENTAL APPROACH
Yeasts that are able to produce carbohydrolases and related enzymes of oenological importance were firstly selected on plates and subsequently identified. Then, a secondary selection of yeasts was carried out according to technological effects of their extracellular enzyme extracts on short macerations. In this way, the colour extraction, total polyphenol content, clarification, filterability and antioxidant activity were studied. This approach makes it possible to correlate the microorganism capacity to produce cell wall-depolymerizing enzymes with their technological effects.
RESULTS AND CONCLUSIONS
From 366 isolates, 96 strains (26.2%) showed at least one of the polysaccharidase activities and 55 strains (57.3%) of them exhibited activities of multiple enzymes that degrade plant cell wall polymers. Sixteen strains were selected and identified as , , and . Pectinolytic enzymes had the highest hydrolytic activity. had a broader enzyme blend and higher activity, dominated by pectinases and followed by xylanases and cellulases. Moreover, the m7-2 strain produced high amounts of polysaccharidase and this was strain-dependent. Strains that produced enzyme extracts with a wide range of activities that were also the highest, also had the best chromatic and technological properties. Cluster analysis confirmed that R-22, m11-2, m86-1 and m86-2 and m7-2 could be correlated with a better effect on filterability, clarification and extraction of bioactive compounds, encouraging future studies regarding their application in winemaking.
NOVELTY AND SCIENTIFIC CONTRIBUTION
The study of yeast multi-enzymatic systems impacting the grape maceration process enables a proper selection criterion for wine yeasts to improve colour extraction, technological parameters and antioxidant activity of Malbec wine. This work shows that and have a high enzymatic potential for oenological purposes.
PubMed: 36816877
DOI: 10.17113/ftb.60.04.22.7777 -
Nectar compounds impact bacterial and fungal growth and shift community dynamics in a nectar analog.Environmental Microbiology Reports Jun 2023Floral nectar is frequently colonised by microbes. However, nectar microbial communities are typically species-poor and dominated by few cosmopolitan genera. One...
Floral nectar is frequently colonised by microbes. However, nectar microbial communities are typically species-poor and dominated by few cosmopolitan genera. One hypothesis is that nectar constituents may act as environmental filters. We tested how five non-sugar nectar compounds as well as elevated sugar impacted the growth of 12 fungal and bacterial species isolated from nectar, pollinators, and the environment. We hypothesised that nectar isolated microbes would have the least growth suppression. Additionally, to test if nectar compounds could affect the outcome of competition between microbes, we grew a subset of microbes in co-culture across a subset of treatments. We found that some compounds such as H O suppressed microbial growth across many but not all microbes tested. Other compounds were more specialised in the microbes they impacted. As hypothesised, the nectar specialist yeast Metschnikowia reukaufii was unaffected by most nectar compounds assayed. However, many non-nectar specialist microbes remained unaffected by nectar compounds thought to reduce microbial growth. Our results show that nectar chemistry can influence microbial communities but that microbe-specific responses to nectar compounds are common. Nectar chemistry also affected the outcome of species interactions among microbial taxa, suggesting that non-sugar compounds can affect microbial community assembly in flowers.
Topics: Plant Nectar; Pollination; Flowers; Yeasts; Bacteria
PubMed: 36779256
DOI: 10.1111/1758-2229.13139 -
Foods (Basel, Switzerland) Jan 2023A fermentation of Fiano di Avellino grape must was carried out at 9°C with the aim of selecting cryotolerant yeast strains and testing their fermentative performances...
A fermentation of Fiano di Avellino grape must was carried out at 9°C with the aim of selecting cryotolerant yeast strains and testing their fermentative performances and volatile production following molecular characterization. A total of 20 yeast cultures were isolated at different fermentation stages. Based on molecular identification and characterization, (.) , (.) , (.) , (.) , , and were found to be the yeast species dominating the fermentation. has been rarely isolated in vineyards and never in the cellar environment. Moreover, in this study, is detected for the first time in vine-wine environments. Both and co-occurred with when grapes were micro-fermented at low temperatures. The growth kinetics of the three species were greatly affected by the fermentation temperature. As a consequence, Fiano wines obtained with and significantly differed from those made by in terms of chemical and volatile composition.
PubMed: 36766056
DOI: 10.3390/foods12030526 -
Ecology and Evolution Feb 2023Organisms are increasingly facing multiple stressors, which can simultaneously interact to cause unpredictable impacts compared with a single stressor alone. Recent...
Organisms are increasingly facing multiple stressors, which can simultaneously interact to cause unpredictable impacts compared with a single stressor alone. Recent evidence suggests that phenotypic plasticity can allow for rapid responses to altered environments, including biotic and abiotic stressors, both within a generation and across generations (transgenerational plasticity). Parents can potentially "prime" their offspring to better cope with similar stressors or, alternatively, might produce offspring that are less fit because of energetic constraints. At present, it remains unclear exactly how biotic and abiotic stressors jointly mediate the responses of transgenerational plasticity and whether this plasticity is adaptive. Here, we test the effects of biotic and abiotic environmental changes on within- and transgenerational plasticity using a - zooplankton-fungal parasite system. By exposing parents and their offspring consecutively to the single and combined effects of elevated temperature and parasite infection, we showed that transgenerational plasticity induced by temperature and parasite stress influenced host fecundity and lifespan; offsprings of mothers who were exposed to one of the stressors were better able to tolerate elevated temperature, compared with the offspring of mothers who were exposed to neither or both stressors. Yet, the negative effects caused by parasite infection were much stronger, and this greater reduction in host fitness was not mitigated by transgenerational plasticity. We also showed that elevated temperature led to a lower average immune response, and that the relationship between immune response and lifetime fecundity reversed under elevated temperature: the daughters of exposed mothers showed decreased fecundity with increased hemocyte production at ambient temperature but the opposite relationship at elevated temperature. Together, our results highlight the need to address questions at the interface of multiple stressors and transgenerational plasticity and the importance of considering multiple fitness-associated traits when evaluating the adaptive value of transgenerational plasticity under changing environments.
PubMed: 36760704
DOI: 10.1002/ece3.9767