Isolation of local strains of the yeast Metschnikowia for biocontrol and lipid production purposes.

The bioprospection of indigenous microorganism strains with biotechnological potential represents a prominent trend. Metschnikowia yeasts exhibit diverse capabilities, such as ethanol reduction in winemaking, biocontrol potential, and lipid production. In this work, local Metschnikowia strains were isolated from different fruits by their ability to produce pulcherrimic acid, a molecule that has been linked to biocontrol activity and that binds iron giving colored colonies. Five strains were selected, each from one of five distinct sources. All of them were identified as M. pulcherrima. All five were able inhibit other yeasts and one M. pulcherrima, called M7, inhibited the growth of Aspergillus nidulans. The selected strains accumulated lipid bodies in stationary phase. Certain non-conventional yeasts like Hanseniaspora vineae are very sensitive to biomass drying, but cell extracts from M. pulcherrima added to the growth media as a source of antioxidant lipids increased their tolerance to drying. All strains isolated showed good stress tolerance (particularly to heat) and have nutrient requirements similar to a commercial M. pulcherrima strain. In addition, the M7 strain had a good growth in sugarcane and beet molasses and behaved like Saccharomyces cerevisiae in a growth medium derived from agricultural waste, a persimmon hydrolysate. Therefore, the isolation of local strains of Metschnikowia able to grow in a variety of substrates is a good source of biocontrol agents.

Aspergillus ochraceus biocontrol by Hanseniaspora opuntiae in vitro and on coffee fruits.

Aspergillus ochraceus is an ochratoxin-producing fungus which contaminates coffee. In this study the antifungal effect of the yeast Hanseniaspora opuntiae on three Aspergillus ochraceus strains (IOC 4417, IOC 4462, Ao 14) was evaluated in vitro and on coffee fruits. H. opuntiae (106 and 107 cells mL-1) reduced in vitro fungal growth from 82% to 87%, when co-cultivated with A. ochraceus. The yeast cell free supernatant (CFS) inhibited conidial germination from 76.5% to 92.5%, and hyphal growth from 54% to 78%. The yeast (107 and 109 cells mL-1) applied on coffee fruits delayed fruit decay by A. ochraceus (IOC 4417 and Ao 14) until the 9th day, and was significantly different (p < 0.05) from the controls. Furthermore, the ultrastructure of the yeast-fungus interaction on the coffee fruit surface showed yeast attachment to A. ochraceus hyphae, and morphological alterations in fungal structures, with hyphal abnormalities, such as tortuous hyphae with irregular, non-uniform surface compared to the control without yeast. H. opuntiae showed efficacy as biocontrol agent and, to the best of our knowledge, this is the first study on the antifungal activity of H. opuntiae against A. ochraceus on coffee fruits Nevertheless, application of H. opuntiae to the crop in the field requires further studies.

Ecological linkages between biotechnologically relevant autochthonous microorganisms and phenolic compounds in sugar apple fruit (Annona squamosa L.).

Our study investigated the potential of Annona squamosa (L.) fruit as a reservoir of yeasts and lactic acid bacteria having biotechnological implications, and phenolics capable of modifying the ecology of microbial consortia. Only a single species of lactic acid bacteria (Enterococcus faecalis) was identified, while Annona fruit seemed to be a preferred niche for yeasts (Saccharomyces cerevisiae, Hanseniaspora uvarum), which were differentially distributed in the fruit. In order to identify ecological implications for inherent phenolics, the antimicrobial potential of water- and methanol/water-soluble extracts from peel and pulp was studied. Pulp extracts did not show any antimicrobial activity against the microbial indicators, while some Gram-positive bacteria (Staphylococcus aureus, Staphylococcus saprophyticus, Listeria monocytogenes, Bacillus megaterium) were susceptible to peel extracts. Among lactic acid bacteria used as indicators, only Lactococcus lactis and Weissella cibaria were inhibited. The chemical profiling of methanol/water-soluble phenolics from Annona peel reported a full panel of 41 phenolics, mainly procyanidins and catechin derivatives. The antimicrobial activity was associated to specific compounds (procyanidin dimer type B [isomer 1], rutin [isomer 2], catechin diglucopyranoside), in addition to unidentified catechin derivatives. E. faecalis, which was detected in the epiphytic microbiota, was well adapted to the phenolics from the peel. Peel phenolics had a growth-promoting effect toward the autochthonous yeasts S. cerevisiae and H. uvarum.

Yeasts from fermented Brazilian fruits as biotechnological tools for increasing phenolics bioaccessibility and improving the volatile profile in derived pulps.

Caatinga Biome fruits have been scarcely explored as a source of biotechnological yeasts. This study isolated yeasts from naturally fermented Caatinga fruits and evaluated Hanseniaspora opuntiae125,Issatchenkia terricola 129, and Hanseniaspora opuntiae 148 on fermentation of soursop and umbu-cajá pulps. All strains were able to ferment the pulps (72 h), increasing (p < 0.05) acetic acid, phenolics concentration and bioaccessibility, and maintaining counts above 7 log CFU/mL after fermentation and/or in vitro digestion. H. opuntiae 125 showed the highest counts (8.43-8.76 log CFU/mL; p < 0.05) in pulps and, higher organic acids production, increased survival to digestion, and higher bioaccessibility of various phenolics (p < 0.05) in the umbu-cajá pulp.I. terricola129 andH. opuntiae 148 showed higher metabolic activity, concentration and bioaccessibility of specific phenolics in umbu-cajá and soursop pulps, respectively (p < 0.05). Volatiles varied (p < 0.05) with the yeast strain. Generally, the yeast biotechnological performance for pulp fermentation was better on its fruit source.

The relative abundances of yeasts attractive to Drosophila suzukii differ between fruit types and are greatest on raspberries.

Fungal metabolic volatiles attract Drosophila suzukii which oviposits in ripening fruits, but there are few data describing the fungal microbiomes of commercial fruits susceptible to this insect pest. We tested the hypothesis that fruit type and ripening stage have a significant effect on fruit surface fungal communities using DNA metabarcoding approaches and found strong support for differences in all three fungal community biodiversity metrics analysed (numbers, types, and abundances of taxa). There was an average fivefold greater difference in fungal communities between sites with different fruit types (strawberry, cherry, raspberry, and blueberry) than across fruit developmental stages, demonstrating site and/or fruit type is the greater factor defining fungal community assemblage. The addition of a fungal internal standard (Plectosphaerella cucumerina) showed cherry had relatively static fungal populations across ripening. Raspberry had a greater prevalence of Saccharomycetales yeasts attractive to D. suzukii, including Hanseniaspora uvarum, which aligns with reports that raspberry is among the fruits with greatest susceptibility and attraction to D. suzukii. Greater knowledge of how yeast communities change during fruit maturation and between species or sites may be valuable for developing methods to manipulate fruit microbiomes for use in integrated pest management strategies to control D. suzukii.

Hanseniaspora uvarum Attracts Drosophila suzukii (Diptera: Drosophilidae) With High Specificity.

Since the early phase of the intercontinental dispersal of Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), fermentation baits have been used for monitoring. Self-made lures and commercial products are often based on wine and vinegar. From an ecological perspective, the formulation of these baits is expected to target especially vinegar flies associated with overripe fruit, such as Drosophila melanogaster (Meigen) (Diptera: Drosophilidae). Hanseniaspora uvarum (Niehaus) (Ascomycota: Saccharomyceta) is a yeast closely associated with D. suzukii and fruit, and furthermore attractive to the flies. Based on this relation, H. uvarum might represent a suitable substrate for the development of lures that are more specific than vinegar and wine. In the field, we therefore, compared H. uvarum to a commercial bait that was based on vinegar and wine with respect to the number of trapped D. suzukii relative to other drosophilids and arthropods. Trap captures were higher with the commercial bait but specificity for D. suzukii was greater with H. uvarum. Moreover, H. uvarum headspace extracts, as well as a synthetic blend of H. uvarum volatiles, were assayed for attraction of D suzukii in a wind tunnel and in the field. Headspace extracts and the synthetic blend induced strong upwind flight in the wind tunnel and confirmed attraction to H. uvarum volatiles. Furthermore, baited with H. uvarum headspace extract and a drowning solution of aqueous acetic acid and ethanol, 74% of field captured arthropods were D. suzukii. Our findings suggest that synthetic yeast headspace formulations might advance the development of more selective monitoring traps with reduced by-catch.

Impact of diseases and pests on premature fruit drop in sweet orange orchards in São Paulo state citrus belt, Brazil.

BACKGROUND: Despite technical improvements in the citrus chain and leadership in orange production achieved in the past decades, premature fruit drop remains a major component of crop loss in São Paulo state citrus belt, the largest sweet orange production area in the world. The present study aimed to determine, during five consecutive seasons, the impact of the diseases and pests on premature fruit drop in the orange belt. RESULTS: Fruit drop due to the main diseases and pests averaged approximately 11.0%, which corresponded to approximately 63% of the annual fruit drop. The average fruit drop rate due to fruit borer and fruit flies combined was 4.0%, Huanglongbing (HLB) 3.3%, black spot 2.6%, leprosis 1.0% and citrus canker 0.3%. The average amount of fruit drop (million 40.8 kg boxes) and value of crop losses (million US$ dollars), in five seasons, were 12.7 and 66.2 for fruit borer/fruit flies, 11.0 and 57.9 for HLB, 8.1 and 42.2 for black spot, 3.1 and 15.6 for leprosis, and 0.9 and 4.9 for citrus canker, respectively. CONCLUSION: Fruit borer and fruit flies (combined), HLB, black spot, leprosis and citrus canker are, in this order, the main diseases and pests in the orange belt of São Paulo state. All of these causes significantly increased the overall fruit drop rate in the evaluated seasons. The results will contribute to the development of the Brazilian citrus industry, while showing to other citrus-growing regions the potential that diseases and pests have to jeopardize production. © 2022 Society of Chemical Industry.

Field and greenhouse application of an attract-and-kill formulation based on the yeast Hanseniaspora uvarum and the insecticide spinosad to control Drosophila suzukii in grapes.

BACKGROUND: The invasive insect Drosophila suzukii (Matsumura) is an important pest of several red grape varieties. The yeast Hanseniaspora uvarum (Niehaus), which is associated with D. suzukii, strongly attracts flies and stimulates them to feed on yeast-laden food. In the present study, a formulation based on H. uvarum culture with spinosad insecticide was applied to the foliage of vineyards and control of D. suzukii was compared to applying spinosad to the whole plant. After successful H. uvarum and insecticide application in the vineyard, we tested additional H. uvarum-based formulations with spinosad in a greenhouse to determine their capacity to control D. suzukii. RESULTS: Application of the H. uvarum-spinosad formulation at 36.4 g of spinosad per hectare reduced the D. suzukii field infestation at the same rate as applying 120 g of spinosad per hectare and prevented spinosad residues on grapes. Leaves treated with H. uvarum and spinosad in the field and transferred to a laboratory assay caused high mortality to flies and reduced the number of eggs laid on fruits. Formulations with spinosad applied in the greenhouse showed that both H. uvarum culture and the yeast cell-free supernatant of a centrifuged culture increased fly mortality and reduced the number of eggs laid compared to the unsprayed control. CONCLUSION: In comparison to typical spinosad spray applications, the use of H. uvarum in combination with spinosad as an attract-and-kill formulation against D. suzukii reduces pesticide residues on the fruits by targeting the treatment to the canopy and decreasing the amount of insecticide per hectare without compromising control efficacy.

Behavioral manipulation of Drosophila suzukii for pest control: high attraction to yeast enhances insecticide efficacy when applied on leaves.

BACKGROUND: The invasive pest, Drosophila suzukii attacks fresh soft-skinned fruit. Broad-spectrum insecticides are implemented for control but there is a need to reduce environmental risks and insecticide residues on fruits. Hanseniaspora uvarum is a yeast frequently found on ripe fruits and associated with D. suzukii. We aim to exploit the ecological association and attraction of D. suzukii to H. uvarum by developing an attract-and-kill strategy, with spray-application on canopy but not fruit. We therefore investigated D. suzukii attraction, egg-laying and mortality when exposed to insecticidal yeast-based formulations. RESULTS: Hanseniaspora uvarum strongly attracted D. suzukii when applied on leaves of grapevine, Vitis vinifera. Notably, this attractiveness was competitive to ripe grape berries that were susceptible to D. suzukii infestation. Moreover, adding H. uvarum enhanced the efficacy of insecticidal formulations against D. suzukii. Flies exposed to leaves treated with yeast-insecticide formulations showed higher mortality and laid a lower number of eggs compared to flies exposed to insecticide alone. In a wind tunnel, all treatments containing H. uvarum alone or in combination with insecticides, caused similar upwind flight and landing at the odor source, which provides evidence that the addition of insecticide did not reduce D. suzukii attraction to yeast. CONCLUSION: Hanseniaspora uvarum can be used to manipulate the behavior of D. suzukii by attracting flies to insecticide formulations. Yeast attraction is competitive to grape berries and improves insecticide effectiveness, suggesting that sprays covering canopy only, could reduce residues on fruit without compromising management efficacy.

Traditional uses, bioactive composition, pharmacology, and toxicology of Phyllanthus emblica fruits: A comprehensive review.

ETHNOPHARMACOLOGICAL RELEVANCE: The fruits of Phyllanthus emblica Linn or Emblica officinalis Gaertn (Phyllanthaceae), (FPE) commonly known as Indian gooseberry or Amla, gained immense importance in indigenous traditional medicinal systems, including Ayurveda, for its medicinal and nutritional benefits. It is used to cure several diseases such as common cold, fever, cough, asthma, bronchitis, diabetes, cephalalgia, ophthalmopathy, dyspepsia, colic, flatulence, hyperacidity, peptic ulcer, erysipelas, skin diseases, leprosy, hematogenesis, inflammation, anemia, emaciation, hepatopathy, jaundice, diarrhea, dysentery, hemorrhages, leucorrhea, menorrhagia, cardiac disorders, and premature greying of hair. AIM OF THE STUDY: In the present review, we presented a comprehensive analysis of the ethnopharmacology, bioactive composition, and toxicity of P. emblica to identify the gap between research and the current applications and to help explore the trends and perspectives for future studies. MATERIALS AND METHODS: We collected the literature published before April 2021 on the phytochemistry, pharmacology, and toxicity of FPE. Literature in English from scientific databases such as PubMed, ScienceDirect, Wiley, Springer, and Google Scholar, books. These reports were analyzed and summarized to prepare this review. The plant taxonomy was verified by "The Plant List" database (http://www.theplantlist.org). RESULTS AND CONCLUSION: s: FPE have been used as a rich source of vitamin C, minerals, and amino acids. Several bioactive molecules were isolated and identified from FPE such as tannins, flavonoids, saponins, terpenoids, alkaloids, ascorbic acid etc. The in vitro and in vivo pharmacological studies on FPE revealed its antimicrobial, antioxidant, anti-inflammatory, anti-diabetic, anticancer, radioprotective, hepatoprotective, immunomodulatory, hypolipidemic, anti-venom, wound healing, HIV-reverse transcriptase effect. Toxicological studies on fruits indicated the absence of any adverse effect even at a high dose after oral administration. CONCLUSIONS: Although FPE showed remarkable therapeutic activities against several diseases such as diabetes, cancer, inflammation, hepatitis B virus, and malaria, there were several drawbacks in some previous reports including the lack of information on the drug dose, standards, controls, and mechanism of action of the extract. Further in-depth studies are required to explain the mechanism of action of the extracts to reveal the role of the bioactive compounds in the reported activities.

Diversity of Mycobiota in Spanish Grape Berries and Selection of Hanseniaspora uvarum U1 to Prevent Mycotoxin Contamination.

The occurrence of mycotoxins on grapes poses a high risk for food safety; thus, it is necessary to implement effective prevention methods. In this work, a metagenomic approach revealed the presence of important mycotoxigenic fungi in grape berries, including Aspergillus flavus, Aspergillus niger aggregate species, or Aspergillus section Circumdati. However, A. carbonarius was not detected in any sample. One of the samples was not contaminated by any mycotoxigenic species, and, therefore, it was selected for the isolation of potential biocontrol agents. In this context, Hanseniaspora uvarum U1 was selected for biocontrol in vitro assays. The results showed that this yeast is able to reduce the growth rate of the main ochratoxigenic and aflatoxigenic Aspergillus spp. occurring on grapes. Moreover, H. uvarum U1 seems to be an effective detoxifying agent for aflatoxin B1 and ochratoxin A, probably mediated by the mechanisms of adsorption to the cell wall and other active mechanisms. Therefore, H. uvarum U1 should be considered in an integrated approach to preventing AFB1 and OTA in grapes due to its potential as a biocontrol and detoxifying agent.

Selective Extraction of Piceatannol from Passiflora edulis by-Products: Application of HSPs Strategy and Inhibition of Neurodegenerative Enzymes.

Passiflora edulis by-products (PFBP) are a rich source of polyphenols, of which piceatannol has gained special attention recently. However, there are few studies involving environmentally safe methods for obtaining extracts rich in piceatannol. This work aimed to concentrate piceatannol from defatted PFBP (d-PFBP) by means of pressurized liquid extraction (PLE) and conventional extraction, using the bio-based solvents selected with the Hansen solubility parameters approach. The relative energy distance (Ra) between solvent and solute was: Benzyl Alcohol (BnOH) < Ethyl Acetate (EtOAc) < Ethanol (EtOH) < EtOH:H2O. Nonetheless, EtOH presented the best selectivity for piceatannol. Multi-cycle PLE at 110 °C was able to concentrate piceatannol 2.4 times more than conventional extraction. PLE exhibited a dependence on kinetic parameters and temperature, which could be associated with hydrogen bonding forces and the dielectric constant of the solvents. The acetylcholinesterase (AChE) and lipoxygenase (LOX) IC50 were 29.420 µg/mL and 27.682 µg/mL, respectively. The results reinforce the demand for processes to concentrate natural extracts from food by-products.

Native yeast and non-yeast fungal communities of Cabernet Sauvignon berries from two Washington State vineyards, and persistence in spontaneous fermentation.

To address a knowledge gap about the grape berry mycobiome from Washington State vineyards, next-generation sequencing of the internal transcribed spacer region (ITS1) was used to identify native yeast and fungal species on berries of cultivar 'Cabernet Sauvignon' from two vineyards at veraison and harvest in 2015 and 2016. Four hundred fifty-six different yeast amplicon sequence variants (ASV), representing 184 distinct taxa, and 2467 non-yeast fungal ASV (791 distinct taxa) were identified in this study. A set of 50 recurrent yeast taxa, including Phaeococcomyces, Vishniacozyma and Metschnikowia, were found at both locations and sampling years. These yeast species were monitored from the vineyard into laboratory-scale spontaneous fermentations. Taxa assignable to Metschnikowia and Saccharomyces persisted during fermentation, whereas Curvibasidium, which also has possible impact on biocontrol and wine quality, did not. Sulfite generally reduced yeast diversity and richness, but its effect on the abundance of specific yeasts during fermentation was negligible. Among the 106 recurring non-yeast fungal taxa, Alternaria, Cladosporium and Ulocladium were especially abundant in the vineyard. Vineyard location was the primary factor that accounted for the variation among both communities, followed by year and berry developmental stage. The Washington mycobiomes were compared to those from other parts of the world. Sixteen recurrent yeast species appeared to be unique to Washington State vineyards. This subset also contained a higher proportion of species associated with cold and extreme environments, relative to other localities. Certain yeast and non-yeast fungal species known to suppress diseases or modify wine sensory properties were present in Washington vineyards, and likely have consequences to vineyard health and wine quality.

Hot air treatment reduces postharvest decay in Chinese bayberries during storage by affecting fungal community composition.

Chinese bayberry fruit were treated with hot air (HA) at 48 ℃ for 3 h and then stored at 4 ℃ for 15 d. Changes in fungal communities were analyzed by high-throughput sequencing (HTS), and decay and fruit quality were monitored during storage. The results showed that HA treatment effectively maintains fruit quality and the richness and diversity of fungal communities. Heat treatment inhibited decay development and reduced the growth of fungi in the genera Botryotinia spp., Davidiella spp., Hanseniaspora spp., and Candida spp. Canonical correspondence analysis further revealed that Botryotinia spp. and Davidiella spp. were positively correlated with fruit decay and weight loss. FUNGuild analysis demonstrated that HA-treated bayberries had a lower relative abundance within the plant pathogen guild, but higher relative abundance within the endophyte guild. The results suggest that HA treatment reduces pathogens by favoring the increase of endophytes, providing new insight into the decay development and quality changes during the storage of postharvest Chinese bayberries.

Impact of Background Fruit Odors on Attraction of Drosophila suzukii (Diptera: Drosophilidae) to Its Symbiotic Yeast.

Background odors produced by plants in the environment can interfere with the response of insects to a point-releasing attractant, especially when their compositions overlap. In this study, a series of binary choice tests was conducted in a wind tunnel to investigate whether background odors emitted from cherry, blueberry, blackberry, or raspberry fruits would affect the level of Drosophila suzukii (Matsumura) attraction to its symbiotic yeast, Hanseniaspora uvarum (Niehaus) (Saccharomycetales: Saccharomycetaceae). Whether an increase in the intensity of background odors would affect the attractiveness of H. uvarum to D. suzukii was also investigated, either by increasing the number of cherry or raspberry fruit per cup or by increasing the number of fruit cups surrounding the cup baited with the yeast. In wind tunnel assays, background fruit odors interfering with D. suzukii attraction to the yeast varied among fruit types. Raspberry odor inhibited the attractiveness of H. uvarum to the fly the most, followed by blackberry odor, whereas cherry and blueberry odors had no significant impact on the attraction. An increase in the intensity of odors by adding more cherry or raspberry fruit per cup did not increase the impact of fruit odor on the attraction; however, adding more raspberry cups around H. uvarum linearly decreased its attractiveness, suggesting that background host fruit abundance and likely increase in host odor may influence D. suzukii attraction to yeast odor depending on host species.

Effect of Debaryomyces hansenii and the antifungal PgAFP protein on Alternaria spp. growth, toxin production, and RHO1 gene expression in a tomato-based medium.

Tomato fruit is susceptible to Alternaria spp. spoilage, which poses a health risk due to their mycotoxin production. Biopreservation relies on the use of whole microorganisms or their metabolites to manage spoilage microorganisms including filamentous fungi. However, the use of treatments at fungistatic level might activate intracellular pathways, which can cause an increment in mycotoxin accumulation. The objective of this work was to evaluate the effect of two strains of Debaryomyces hansenii and the antifungal protein PgAFP at 10 and 40 µg/mL. Both growth and production of two of the most common mycotoxins (tenuazonic acid and alternariol monomethyl ether) by Alternaria tenuissima sp.-grp. and Alternaria arborescens sp.-grp. on a tomato-based matrix, were analysed at 12 °C. Additionally, the impact of these biocontrol agents on the stress-related RHO1 gene expression was assessed. All treatments reduced mycotoxin accumulation (from 27 to 92% of inhibition). Their mode of action against Alternaria spp. in tomato seems unrelated to damages to fungal cell wall integrity at the genomic level. Therefore, the two D. hansenii strains (CECT 10352 and CECT 10353) and the antifungal protein PgAFP at 10 µg/mL are suggested as biocontrol strategies in tomato fruit at postharvest stage.

Impact of antagonistic yeasts from wine grapes on growth and mycotoxin production by Alternaria alternata.

AIMS: Alternaria alternata is a major contaminant of wine grapes, meaning a health risk for wine consumers due to the accumulation of toxic metabolites. To develop a successful biofungicide, the effectiveness of epiphytic wine grape yeasts against A. alternata growth and toxin production was assessed in vitro under temperature and aW conditions that simulate those present in the field. METHODS AND RESULTS: The effect of 14 antagonistic yeasts was evaluated on growth and alternariol (AOH), alternariol monomethyl ether (AME) and tenuazonic acid (TA) production by three A. alternata strains in a synthetic medium with composition similar to grape (SN) at three temperatures (15, 25 and 30°C). All Metschnikowia sp. yeast strains evaluated completely prevented A. alternata growth and mycotoxin production at all temperatures in SN medium. Meanwhile, the growth inhibition exerted by Starmerella bacillaris yeast strains was higher at 30°C, followed by 25 and 15°C, being able to show a stimulating or inhibiting effect. Hanseniaspora uvarum yeast strains showed a growth promoting activity higher at 15°C, followed by 25 and 30°C. Even at conditions where A. alternata growth was stimulated by the S. bacillaris and H. uvarum yeasts, high inhibitions of mycotoxin production (AOH, AME and TA) were observed, indicating a complex interaction between growth and mycotoxin production. CONCLUSION: There is a significant influence of temperature on the effectiveness of biocontrol against A. alternata growth and mycotoxin production. Metschnikowia sp. strains are good candidates to compose a biofungicide against A. alternata. SIGNIFICANCE AND IMPACT OF THE STUDY: Among the different antagonistic yeasts evaluated, only Metschnikowia sp. strains were equally effective reducing A. alternata growth and mycotoxin at different temperatures underlining the importance of considering environmental factors in the selection of the antagonists.

Selection and application of antifungal VOCs-producing yeasts as biocontrol agents of grey mould in fruits.

Rotting caused by grey mould (Botrytis cinerea) is a concerning disease for numerous crops both pre- and postharvest stages. Application of antagonistic yeasts is a promising strategy for controlling grey mould incidence which could mitigate undesirable consequences of using synthetic fungicides. In this work, a screening for detection of yeasts isolated from figs producers of antifungal volatile organic compounds (VOCs) were performed by confrontation in double dishes systems. Eleven out of 34 yeasts confronted reduced B. cinerea growth parameter in vitro. This reduction was correlated (p ≤ 0.050) with the production of 10 volatile compounds: two acids (acetic acid and octanoic acid), 7 esters (Ethyl propionate, n-Propyl acetate, Isobutyl acetate, 2-methylbutyl acetate, furfuryl acetate, phenylmethyl acetate, 2-phenylethyl acetate) and one ketone (Heptan-2-one). In bases on in vitro assay, Hanseniaspora uvarum 793 was applied to in vivo assays with strawberries and cherries. The reduction of incidence of B. cinerea in strawberries at 7 °C and 25 °C was 54.9 and 72.1% after 6 and 3 days, respectively. The reduction of incidence of B. cinerea in cherries at 7 °C and 25 °C was 48.9 and 45.6% after 5 and 4 days, respectively. These results showed that VOCs produced by Hanseniaspora uvarum 793 are effective in the control of incidence of Botrytis cinerea in fruits, being a potential alternative to chemical fungicide.

Preparation and characterization of bacterial cellulose produced from fruit and vegetable peels by Komagataeibacter hansenii GA2016.

This study focused on the investigation of bacterial cellulose production potency of some fruit and vegetable peels (cucumber, melon, kiwifruit, tomato, apple, quince and pomegranate) with Komagataeibacter hansenii GA2016. Fruit and vegetable peels were hydrolyzed, used for bacterial cellulose (BC) production and their chemical, physical, thermal and structural features were compared to BC from Hestrin-Schramm medium (HSBC) and plant cellulose (CP). Except for pomegranate peel hydrolysate, all the fruit and vegetable peel hydrolysates supplied to K. hansenii GA2016 supported the BC production. Among the fruit and vegetable peel hydrolysates, the highest BC production was observed in kiwifruit peel hydrolysate (11.53%), while the lowest production was observed in apple peel hydrolysate (1.54%). Water-holding capacities of the BCs were ranged from 627.50% to 928.79% and higher than HSBC (609.30%), average fiber diameters were ranged from 47.64 nm to 61.11 nm and thinner than HSBC (74.29) and CP (10,420 nm), crystallinities were ranged from 80.27% to 92.96%, thermal capacities BCs were higher than HSBC and CP. For the BC productions, utilization of the fruit and vegetable peels as the sole nutrient source could reduce the production costs and among the polysaccharides, increase the use of BC in industry.

Yeasts Associated with Various Amazonian Native Fruits.

Yeasts, commonly present on the surface of fruits, are of industrial interest for the production of enzymes, flavorings, and bioactive compounds, and have many other scientific uses. The Amazonian rainforest may be a good source of new species or strains of yeasts, but their presence on Amazonian fruits is unknown. The aim of this study was to identify and characterize yeasts isolated from Amazonian native fruits using molecular and phenotypic methods. In total, 81 yeast isolates were obtained from 10 fruits species. Rep-PCR showed 29 strain profiles. Using a combination of restriction-fragment length polymorphism (RFLP) of the 5.8S-ITS region and D1/D2 sequencing of the 26S rRNA gene, 16 species were identified belonging to genera Candida, Debaryomyces, Hanseniaspora, Kodamaea, Martiniozyma, and Meyerozyma. The most dominant species were Candida tropicalis, Debaryomyces hansenii, Hanseniaspora opuntiae, and Hanseniaspora thailandica. H. opuntiae and H. thailandica showed the highest number of the strain profiles. Phenotypic profiles were variable between species, and even among strains. Screening for hydrolases showed lipolytic activity in only one isolate, while proteolytic, cellulolytic and amylolytic capabilities were not detected. Yeast presence among fruits varied, with cidra (Citrus medica) and ungurahui (Oenocarpus bataua) having the highest number of species associated. This investigation broadens the understanding and possible biotechnological uses of yeast strains obtained from Amazonian native fruits.Yeasts, commonly present on the surface of fruits, are of industrial interest for the production of enzymes, flavorings, and bioactive compounds, and have many other scientific uses. The Amazonian rainforest may be a good source of new species or strains of yeasts, but their presence on Amazonian fruits is unknown. The aim of this study was to identify and characterize yeasts isolated from Amazonian native fruits using molecular and phenotypic methods. In total, 81 yeast isolates were obtained from 10 fruits species. Rep-PCR showed 29 strain profiles. Using a combination of restriction-fragment length polymorphism (RFLP) of the 5.8S-ITS region and D1/D2 sequencing of the 26S rRNA gene, 16 species were identified belonging to genera Candida, Debaryomyces, Hanseniaspora, Kodamaea, Martiniozyma, and Meyerozyma. The most dominant species were Candida tropicalis, Debaryomyces hansenii, Hanseniaspora opuntiae, and Hanseniaspora thailandica. H. opuntiae and H. thailandica showed the highest number of the strain profiles. Phenotypic profiles were variable between species, and even among strains. Screening for hydrolases showed lipolytic activity in only one isolate, while proteolytic, cellulolytic and amylolytic capabilities were not detected. Yeast presence among fruits varied, with cidra (Citrus medica) and ungurahui (Oenocarpus bataua) having the highest number of species associated. This investigation broadens the understanding and possible biotechnological uses of yeast strains obtained from Amazonian native fruits.