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Ecology and Evolution Apr 2024Secondary metabolites produced by primary producers have a wide range of functions as well as indirect effects outside the scope of their direct target. Research...
Secondary metabolites produced by primary producers have a wide range of functions as well as indirect effects outside the scope of their direct target. Research suggests that protease inhibitors produced by cyanobacteria influence grazing by herbivores and may also protect against parasites of cyanobacteria. In this study, we asked whether those same protease inhibitors produced by cyanobacteria could also influence the interactions of herbivores with their parasites. We used the - zooplankton host-fungal parasite system to address this question because it is well documented that cyanobacteria protease inhibitors suppress trypsin and chymotrypsin in the gut of , and because it is known that infects via the gut. We tested the hypothesis that gut proteases are necessary for spores to be released from their asci. We then also tested whether diets that decrease trypsin and chymotrypsin activity in the guts of lead to lower levels of infection. Our results show that chymotrypsin promotes the release of the fungal spores from their asci. Moreover, a diet that strongly inhibited chymotrypsin activity in decreased infection levels, particularly in the most susceptible clones. Our results support the growing literature that cyanobacterial diets can be beneficial to zooplankton hosts when challenged by parasites and uncover a mechanism that contributes to the protective effect of cyanobacterial diets. Specifically, we demonstrate that host chymotrypsin enzymes promote the dehiscence of spores; when cyanobacteria inhibit the activity of chymotrypsin in hosts, this most likely traps the spore inside the ascus, preventing the parasite from puncturing the gut and beginning the infection process. This study illustrates how secondary metabolites of phytoplankton can protect herbivores against their own enemies.
PubMed: 38646007
DOI: 10.1002/ece3.11340 -
Journal of Fish Diseases Feb 2024During breeding, some oriental river prawns (Macrobrachium nipponense, de Haan), an important aquaculture species in China, exhibit yellowish-brown body colouration,...
During breeding, some oriental river prawns (Macrobrachium nipponense, de Haan), an important aquaculture species in China, exhibit yellowish-brown body colouration, reduced appetite, and vitality. Diseased prawns revealed characteristic emulsifying disease signs, including whitened musculature, hepatopancreatic tissues, milky haemolymph, and non-coagulation. The present study investigated the causative agent of M. nipponense infection through isolation, histopathology, molecular sequencing, and infection experiments. The pathogenic strain exhibited distinctive white colonies on Bengal red medium, with microscopic examination confirming the presence of yeast cells. Histopathological analysis revealed prominent pathological alterations and yeast cell infiltration in muscles, hepatopancreas and gills. Additionally, 26S rDNA sequencing of the isolated yeast strain LNMN2022 revealed Metschnikowia bicuspidata (GenBank: OR518659) as the causative agent. This strain exhibited a 98.28% sequence homology with M. bicuspidata LNMB2021 (GenBank: OK094821) and 96.62% with M. bicuspidata LNES0119 (GenBank: OK073903). The pathogenicity test confirmed that M. bicuspidata elicited clinical signs in M. nipponense consistent with those observed in natural populations, and the median lethal concentration was determined to be 3.3 × 10 cfu/mL. This study establishes a foundation for further investigations into the host range and epidemiological characteristics of the pathogen M. bicuspidata in aquatic animals and provides an empirical basis for disease management in M. nipponense.
PubMed: 38421366
DOI: 10.1111/jfd.13936 -
Fungal Biology Jun 2024Volatile organic compounds (VOCs) produced by yeasts can positively affect crops, acting as antifungals or biostimulants. In this study, Aureobasidium pullulans and...
Volatile organic compounds (VOCs) produced by yeasts can positively affect crops, acting as antifungals or biostimulants. In this study, Aureobasidium pullulans and Metschnikowia pulcherrima were evaluated as potential antagonists of Trichoderma spp., common fungal pathogen in mushroom cultivation. To assess the biocontrol ability and biostimulant properties of the selected yeast species, in vitro co-culture and VOCs exposure assays were conducted. In both assays, VOCs produced by Aureobasidium spp. showed the stronger antifungal activity with a growth inhibition up to 30 %. This result was further confirmed by the higher volatilome alcohol content revealed by solid phase microextraction-gas chromatography mass spectrometry (SPME/GC-MS). Overall, Aureobasidium strains can be potentially used as biocontrol agent in Pleorotus ostreatus and Cyclocybe cylindracea mycelial growth, without affecting their development as demonstrated by VOCs exposure assay and Fourier-transform infrared spectroscopy (FT-IR). Conversely, M. pulcherrima was characterized by a lower or absent antifungal properties and by a volatilome composition rich in isobutyl acetate, an ester often recognized as plant growth promoter. As confirmed by FT-IR, Lentinula mycelia exposed to M. pulcherrima VOCs showed a higher content of proteins and lipids, suggesting an improvement of some biochemical properties. Our study emphasizes that VOCs produced by specific yeast strains are potentially powerful alternative to synthetic fungicide in the vegetative growth of mushroom-forming fungi and also able to modify their biochemical composition.
Topics: Volatile Organic Compounds; Mycelium; Agaricales; Gas Chromatography-Mass Spectrometry; Antifungal Agents; Biological Control Agents; Metschnikowia; Antibiosis; Aureobasidium; Trichoderma; Solid Phase Microextraction
PubMed: 38876538
DOI: 10.1016/j.funbio.2024.05.007 -
International Journal of Food... Feb 2024The co-occurrence of fungi and mycotoxins in various foods has been frequently reported in many countries, posing a serious threat to the health and safety of consumers....
The co-occurrence of fungi and mycotoxins in various foods has been frequently reported in many countries, posing a serious threat to the health and safety of consumers. In this study, the mycobiota in five types of commercial bee pollen samples from China were first revealed by DNA metabarcoding. Meanwhile, the content of total aflatoxins in each sample was investigated by high-performance liquid chromatography with fluorescence detection. The results demonstrated that Cladosporium (0.16 %-89.29 %) was the most prevalent genus in bee pollen, followed by Metschnikowia (0-81.12 %), unclassified genus in the phylum Ascomycota (0-81.13 %), Kodamaea (0-73.57 %), and Penicillium (0-36.13 %). Meanwhile, none of the assayed aflatoxins were determined in the 18 batches of bee pollen samples. In addition, the fungal diversity, community composition, and trophic mode varied significantly among five groups. This study provides comprehensive information for better understanding the fungal communities and aflatoxin residues in bee pollen from different floral origins in China.
Topics: Animals; Bees; Aflatoxins; Mycotoxins; Penicillium; Chromatography, High Pressure Liquid; Pollen; Food Contamination; Fungi
PubMed: 38043476
DOI: 10.1016/j.ijfoodmicro.2023.110511 -
Foods (Basel, Switzerland) Feb 2024As a biological alternative to the antimicrobial action of SO, bioprotection has been proposed to winemakers as a means to limit or prevent grape musts microbial...
As a biological alternative to the antimicrobial action of SO, bioprotection has been proposed to winemakers as a means to limit or prevent grape musts microbial alteration. Competition for nitrogenous nutrients and for oxygen are often cited as potential explanations for the effectiveness of bioprotection. This study analyses the effect of a bioprotective strain on the growth of one strain and one strain. Bioprotection efficiency was observed only against inoculated at the two lowest concentrations. These results indicate a potential species-dependent efficiency of the bioprotective strain and a strong impact of the initial ratio between bioprotective and apiculate yeasts. The analysis of the consumption of nitrogen compounds revealed that leucine, isoleucine, lysine and tryptophan were consumed preferentially by all three strains. The weaker assimilation percentages of these amino acids observed in at 24 h growth suggest competition with that could negatively affects the growth of the apiculate yeast in co-cultures. The slowest rate of O consumption of strain, in comparison with , was probably not involved in the bioprotective effect. Non-targeted metabolomic analyses of and co-culture indicate that the interaction between both strains particularly impact lysin and tryptophan metabolisms.
PubMed: 38472837
DOI: 10.3390/foods13050724 -
International Journal of Food... Apr 2024Alternaria alternata is a common fungal pathogen causing postharvest decay in table grapes. This study addressed the potential of autochthonous yeasts and bioactive...
Alternaria alternata is a common fungal pathogen causing postharvest decay in table grapes. This study addressed the potential of autochthonous yeasts and bioactive compounds of natural sources to act as biocontrol agents (BCAs) against A. alternata in cold-stored table grapes. With this purpose, 19 yeast capable of growing at 0-1 °C were isolated from the surface of Red Globe table grapes. These isolates, along with the pre-isolated strain Metschnikowia pulcherrima RCM2, were evaluated as BCAs in wounded berries. From these results, six yeast isolates were pre-selected to be combined with bioactive compounds of natural sources, like phenolic compounds (PCs) of side streams of wine industry, including bunch stem extract (BSE) (5-25 %), and cane extract (CE) (5-25 %), and functional polysaccharides from shrimp waste such as chitosan (CH) (0.5 %). Then, the biocontrol efficacy of combined treatments beyond individual ones was compared. The results revealed that 4 yeast isolates, namely M. pulcherrima RCM2 and ULA146, and Aureobasidium pullulans FUL14 and FUL18, were the most effective. However, when combined with the natural bioactive compounds, their efficacy against A. alternata did not increase significantly. Notably, ULA146 and FUL18 demonstrated a biocontrol efficacy of 36-37 %, comparable to that of the treatment with commercial doses of SO, which only showed a 27 % reduction in the lesion diameter. These findings highlight the potential of using psychrotrophic yeasts as BCAs against A. alternata in cold-stored table grapes. Combining these yeast strains with BSE, CE and CH did not increase BCAs efficacy against this pathogen at the concentrations tested. The development of effective biocontrol strategies for A. alternata could contribute to reducing reliance on chemically synthesized fungicides, promoting sustainable practices, aiming to improve the quality and safety of cold-stored table grapes.
Topics: Vitis; Yeasts; Alternaria; Fungicides, Industrial
PubMed: 38442539
DOI: 10.1016/j.ijfoodmicro.2024.110640