Volatilom und Transkriptom des Speisepilzes Agrocybe aegerita

Heat stress induces oxidative stress in Pleurotus ostreatus (P. ostreatus), inhibiting the growth of both mycelium and fruiting bodies. While various studies have analyzed the physiological responses of P. ostreatus under heat stress conditions, comprehensive research comparing physiological responses in mycelium and fruiting bodies through metabolomic analysis of volatile organic compounds has not been conducted. In this study, we invested the levels of volatile organic compounds (VOCs), the activity of VOC synthesis-related enzymes, and the expression of heat resistance-related genes in mycelium and fruiting bodies exposed to heat stress. The total VOC levels measured in mycelium increased, whereas those in fruiting bodies decreased, indicating contrasting responses. In fruiting bodies, following heat stress, the synthesis of 1-Octen-3-ol was inhibited by glutathione peroxidase (GPx), and its conversion to 3-Octanone was accelerated by alcohol dehydrogenase (ADH), resulting in a significant decrease in 1-Octen-3-ol levels. In mycelium, both GPx gene expression levels and ADH activity remained unchanged under heat stress conditions, and 1-Octen-3-ol levels did not decrease. Comparison of heat resistance-related gene expression through quantitative PCR revealed that in mycelium, the expression of genes related to trehalose and heat shock proteins increased, while in fruiting bodies, the expression of genes related to antioxidant enzymes, including GPx, increased. In conclusion, we identified distinct heat resistance responses in mycelium and fruiting bodies, which had different effects on VOC synthesis, leading to contrasting changes.

Both fungi and bacteria emit many volatile organic compounds (VOCs) as mixtures of low molecular mass alcohols, aldehydes, esters, terpenoids, thiols, and other small molecules that easily volatilize. Most determination (separation and identification) of VOCs now relies on gas chromatography–mass spectrometry (GC-MS) but developments in “electronic nose” technology promise to revolutionize the field. Microbial VOC profiles are both complex and dynamic: the compounds produced and their abundance vary with the producing species, the age of the colony, water availability, the substrate, the temperature, and other environmental parameters. The single most commonly reported volatile from fungi is 1-octen-3-ol which is a breakdown product of linoleic acid. It functions as a hormone within many fungal species, serves as both an attractant and deterrent for certain species of arthropods, and exhibits toxicity at relatively low concentrations in model systems. Bacterial and fungal VOCs have been studied by scientists from a broad range of subdisciplines in both theoretical and applied contexts. VOCs are exploited for their food and flavor properties, their use as indirect indicators of microbial growth, their ability to stimulate plant growth, and their ability to attract insect pests. Because these compounds can diffuse a long way from their point of origin, they are excellent chemical signaling molecules (semiochemicals) in non-aqueous habitats and facilitate the ability of microbes to engage in “chemical conversations.” The physiological effects of bacterial and fungal VOCs in host–pathogen relationships and in mediating interspecific associations in natural ecosystem functioning is an emerging frontier for future research.

BackgroundCyclocybe aegerita (syn. Agrocybe aegerita) is a commercially cultivated mushroom. Its archetypal agaric morphology and its ability to undergo its whole life cycle under laboratory conditions makes this fungus a well-suited model for studying fruiting body (basidiome, basidiocarp) development. To elucidate the so far barely understood biosynthesis of fungal volatiles, alterations in the transcriptome during different developmental stages of C. aegerita were analyzed and combined with changes in the volatile profile during its different fruiting stages.ResultsA transcriptomic study at seven points in time during fruiting body development of C. aegerita with seven mycelial and five fruiting body stages was conducted. Differential gene expression was observed for genes involved in fungal fruiting body formation showing interesting transcriptional patterns and correlations of these fruiting-related genes with the developmental stages. Combining transcriptome and volatilome data, enzymes putatively involved in the biosynthesis of C8 oxylipins in C. aegerita including lipoxygenases (LOXs), dioxygenases (DOXs), hydroperoxide lyases (HPLs), alcohol dehydrogenases (ADHs) and ene-reductases could be identified. Furthermore, we were able to localize the mycelium as the main source for sesquiterpenes predominant during sporulation in the headspace of C. aegerita cultures. In contrast, changes in the C8 profile detected in late stages of development are probably due to the activity of enzymes located in the fruiting bodies.ConclusionsIn this study, the combination of volatilome and transcriptome data of C. aegerita revealed interesting candidates both for functional genetics-based analysis of fruiting-related genes and for prospective enzyme characterization studies to further elucidate the so far barely understood biosynthesis of fungal C8 oxylipins.

Background Following creation of an IPAA in patients with ulcerative colitis (UC), more than 60% of subjects develop inflammatory complications. The current objective assessment for inflammation of the pouch is limited to surrogate stool and blood biomarkers or endoscopy. The development of non-invasive and accurate biomarkers for the assessment of IPAA inflammation is an area of unmet need. Measurement of exhaled breath volatile organic metabolome compounds (VOCs) has shown promise as a biomarker for the diagnosis and monitoring of inflammatory disorders. We here aimed to characterize the pattern of VOCs in the exhaled breath of patients with an IPAA and assess whether VOC analysis is able to discriminate patients with endoscopically active IPAA inflammation from patients without IPAA inflammation. Methods This is a cross-sectional study of patients with an IPAA created for the management of UC. Exhaled breath samples were collected at time of endoscopic evaluation of the pouch and 97 VOC metabolites assessed via selective ion flow tube mass spectrometry (SIFT-MS). The IPAA cohort was dichotomized using the endoscopic pouch disease activity index (PDAI) into endoscopic PDAI of >= 4 (severe inflammation), or endoscopic PDAI score <= 1 (mild or no inflammation). Principle component analysis (PCA) was conducted to reveal the VOCs with the strongest discriminatory capability and principle component regression (PCR) was performed to assess the association of exhaled breath VOC analysis in differentiating the groups. Results Exhaled breath metabolome analysis was performed on 10 subjects with PDAI >=4 and 7 subjects with PDAI <=1. Demographics are provided in Table 1. PCA indicated robust discrimination of the two groups based on breath VOCs (Figure 1). 10 out of 97 VOCs were up-regulated in the PDAI >=4 group compared to control, including ammonia and hydrogen sulfide. Isopropenyltoluene, tetrachloroethylene, and 3-pentanone provided the highest contribution to differentiate between the cohorts (Figure 2). Receiver operative curve (ROC) analysis of the PCR model indicated an area under the curve (AUC) of 0.81 (0.61-99), suggesting a strong association of breath VOCs with inflammation of the pouch (Figure 1). Conclusion VOC exhaled breath metabolome analysis shows a strong ability to discriminate patients with severe endoscopic pouch inflammation from patients with minimal to no endoscopic inflammation. The differences in reported VOCs point toward metabolic differences in bacterial fermentation, lipid and carbohydrate metabolism, and an increase in reactive oxygen species in patients with endoscopic pouch inflammation. Validation studies addressing the role of VOC analysis for non-invasive disease assessment patients with IPAA are ongoing.

We reviewed the impact of fungal volatile organic compounds (VOCs) on soil-inhabiting organisms and their physiological and molecular consequences for their targets. Because fungi can only move by growth to distinct directions, a main mechanism to protect themselves from enemies or to manipulate their surroundings is the secretion of exudates or VOCs. The importance of VOCs in this regard has been significantly underestimated. VOCs not only can be means of communication, but also signals that are able to specifically manipulate the recipient. VOCs can reprogram root architecture of symbiotic partner plants or increase plant growth leading to enlarged colonization surfaces. VOCs are also able to enhance plant resistance against pathogens by activating phytohormone-dependent signaling pathways. In some cases, they were phytotoxic. Because the response was specific to distinct species, fungal VOCs may contribute to regulate the competition of plant communities. Additionally, VOCs are used by the producing fungus to attack rivaling fungi or bacteria, thereby protecting the emitter or its nutrient sources. In addition, animals, like springtails, nematodes, and earthworms, which are important components of the soil food web, respond to fungal VOCs. Some VOCs are effective repellents for nematodes and, therefore, have applications as biocontrol agents. In conclusion, this review shows that fungal VOCs have a huge impact on soil fauna and flora, but the underlying mechanisms, how VOCs are perceived by the recipients, how they manipulate their targets and the resulting ecological consequences of VOCs in inter-kingdom signaling is only partly understood. These knowledge gaps are left to be filled by future studies.

In fungi, little is known about connections between volatile organic compound (VOC) formation and developmental stages that are amongst others triggered by fruiting-related genes (FRGs). We analysed the volatilomes of Schizophyllum commune during different developmental stages in a variety of FRG-deletion strains and wild-type strains. The deletion strains Δtea1Δtea1, Δwc-2Δwc-2 and Δhom2Δhom2 were unable to develop fruiting bodies, and Δfst4Δfst4 formed only rudimentary fruiting body structures. Early developmental stages of these strains were dominated by esters, including methyl 2-methylbutanoate, ethyl 2-methylbutanoate, isobutyl 2-methylpropionate, and 2-methylbutyl acetate, of which the last three were not found in the headspace (HS) of the wild-type samples. Compared to the wild type, in the HS of hom2con samples, that are able to form fruiting bodies, methyl 2-methylbutanoate was the most abundant substance at early stages (68–81% of the total peak area). In contrast to fruiting body forming strains, Δtea1Δtea1, Δwc-2Δwc-2, Δhom2Δhom2 and Δfst4Δfst4 showed less sesquiterpenes in the HS. However, the sesquiterpenes found in the HS of FRG-deletion strains, namely, (E)-nerolidol, δ-cadinene, L-calamenene, α-bisabolol and β-bisabolene, were not present in hom2con or wild-type strains that mainly formed fruiting bodies and barely mycelium. Several sesquiterpenes, including α-guaiene, chamigrene and γ-gurjunene, were only found in presence of fruiting bodies. Our results show remarkable connections between FRGs, fruiting body development and VOC production in S. commune, especially counting for sesquiterpenes. Future studies are needed to reveal whether FRGs directly regulates VOC formation or indirectly by changing the phenotype.

Online sequential analysis of volatile and semivolatile organic compounds in water matrices by double robotic sample preparations and dual-channel mono and comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry system

Beneficial soil microorganisms can affect plant growth and resistance by the production of volatile organic compounds (VOCs). Yet, little is known on how VOCs from soil-borne plant pathogens affect plant growth and resistance. Here we show that VOCs released from mycelium and sclerotia of the fungal root pathogen Rhizoctonia solani enhance growth and accelerate development of Arabidopsis thaliana. Seedlings briefly exposed to the fungal VOCs showed similar phenotypes, suggesting that enhanced biomass and accelerated development are primed already at early developmental stages. Fungal VOCs did not affect plant resistance to infection by the VOC-producing pathogen itself but reduced aboveground resistance to the herbivore Mamestra brassicae. Transcriptomics of A. thaliana revealed that genes involved in auxin signaling were up-regulated, whereas ethylene and jasmonic acid signaling pathways were down-regulated by fungal VOCs. Mutants disrupted in these pathways showed similar VOC-mediated growth responses as the wild-type A. thaliana, suggesting that other yet unknown pathways play a more prominent role. We postulate that R. solani uses VOCs to predispose plants for infection from a distance by altering root architecture and enhancing root biomass. Alternatively, plants may use enhanced root growth upon fungal VOC perception to sacrifice part of the root biomass and accelerate development and reproduction to survive infection.

Dardanelles strait has a crucial importance on marine transport, splitting Çanakkale city. Combustion-related anthropogenic sources emit volatile organic compounds (VOCs) into the air and they have public concern due to adverse health effects. In this study, composition of ambient VOCs across Dardanelles strait was monitored for 4 seasons over the year of 2018. A total of 12 sampling locations, including 5 locations on the European and 7 locations on the Asian seashores of Dardanelles strait were determined as sampling points. Standard methods were followed during the sampling and analysis of VOCs. VOCs samples were collected on thermal desorber tubes, containing sorbents of Tenax TA and Carbograph 1TD. Active VOC samples were collected by an air sampling pump and passive VOCs samples were exposed to air for 2 weeks. VOCs samples were analyzed by Thermal Desorber followed by Gas Chromatography – Flame Ionization Detector. Target VOCs in this study were paraffins and aromatic hydrocarbons. Limit of quantification was assessed as ≤ 0.1 µg/m3. According to the results of the study, VOCs concentrations varied both spatially and seasonally. The most abundant VOCs in the air were n-pentane, n-hexane, toluene, benzene, and 1,2,4-trichlorobenzene throughout the study. Furthermore, the highest VOCs levels mostly occurred at the locations that were close to the traffic sources and/or residential areas.

Increasing interest is noticed in the potential of volatile organic compound (VOC) analysis as non-invasive diagnostic biomarker in clinical medical practice. The spectrum of VOCs, originating from (patho)physiological metabolic processes in the human body and detectable in bodily excrements, such as exhaled breath, urine and feces, harbors a magnificent source of information. Thus far, the majority of studies have focused on VOC analysis in exhaled breath, aiming at identification of disease-specific VOC profiles. Recently, an increasing number of studies have evaluated the usability of VOC present in the headspace of feces in the diagnostic work-up of a wide range of gastrointestinal diseases. Promising results have been demonstrated particularly in those diseases in which microbiota alterations are considered to play a significant etiological role, such as colorectal carcinoma, inflammatory bowel disease, irritable bowel syndrome, celiac disease and infectious bowel diseases. In addition, fecal VOC analysis seems to have potential as a diagnostic biomarker for extra-intestinal diseases, including bronchopulmonary dysplasia and sepsis. Different methods for VOC analysis have been used in medical studies, such as gas-chromatography mass spectrometry, selected-ion flow tube-mass spectrometry, ion-mobility spectrometry, and electronic nose devices. In this review, the available literature on the potential of fecal VOCs as diagnostic biomarker, including an overview of relevant VOC detection techniques, is discussed. In addition, future hurdles, which need to be taken prior to implementation of VOC analysis in daily clinical practice, are outlined.

Various techniques have been employed in the analysis of volatile organic compounds (VOCs). However, these techniques are insufficient for the precise analysis of tobacco smoke VOCs because of the complexity of the operating system, system instability, or poor sensitivity. To overcome these problems, a combined system of VOC preconcentrator, gas chromatograph, and olfactometer has been developed. The performance of this new system was evaluated in the analysis of VOCs in tobacco smoke and applied to the odor profiling of sidestream smoke (SSS) that has not been sufficiently investigated in the past. A VOC sample in a gas-sampling bag was injected into a gas chromatograph through a preconcentrator, where it was concentrated, dehydrated, and cryo-focused. Separated VOCs were introduced into a mass spectrometer (for qualitative and quantitative analysis) and a sniffing port (for odor profiling) by a splitting device. In addition to the conventional Gas Chromatography-Olfactometry (GC-O) technique that was used for describing the odor quality of each compound, the odor intensity was estimated based on the dilution ratio of the sample, Aroma Direct Dilution Analysis (ADDA). Also, the contribution of each VOC to the overall SSS odor was estimated by sensory evaluation. This system permitted adequate characterization of the VOCs. The reproducibility of quantification was also good enough with Coefficient of Variation (CV) values less than about 5% (n = 5). With the GC-O technique, we obtained an SSS odor profile composed of over 30 odorants. ADDA indicated that seven odorants were sufficient to characterize SSS odor. In addition, the omit-test revealed that three odor attributes, (‘metallic’, ‘potato-like’, and ‘popcorn-like’) were most important for the characterization of SSS odor.

Fungi are implicated in poor indoor air quality and may pose a potential risk factor for building/mold related illnesses. Fungi emit numerous volatile organic compounds (VOCs) as alcohols, esters, ethers, ketones, aldehydes, terpenoids, thiols, and their derivatives. The toxicity profile of these VOCs has never been explored in a model organism, which could enable the performance of high throughput toxicological assays and lead to a better understanding of the mechanism of toxicity. We have established a reductionist Drosophila melanogaster model to evaluate the toxicity of fungal VOCs. In this report, we assessed the toxicity of fungal VOCs emitted from living cultures of species in the genera, Trichoderma, Aspergillus, and Penicillium and observed a detrimental effect on larval survival. We then used chemical standards of selected fungal VOCs to assess their toxicity on larval and adult Drosophila. We compared the survival of adult flies exposed to these fungal VOCs with known industrial toxic chemicals (formaldehyde [37%], xylene, benzene, and toluene). Among the tested fungal VOC standards, the compounds with eight carbons (C8) caused greater truncation of fly lifespan than tested non-C8 fungal VOCs and industrial toxins. Our data validate the use of Drosophila melanogaster as a model with the potential to elucidate the mechanistic attributes of different toxic VOCs emitted by fungi and also to explore the potential link between reported human illnesses/symptoms and exposure to water damaged and mold contaminated buildings.

The observation and analysis of volatile organic compounds (VOCs) were conducted during January 2018 in nine prefecture-level cities of Sichuan, China, covering the period of heavily polluted weather. Air samples collected in nine prefecture-level cities were analyzed using a preconcentration method coupled with GC-MS/FID. The characteristics and ozone generation potential (OFP) of VOCs were analyzed. The relationship between air quality index (AQI) and VOCs and gross domestic product (GDP) and VOCs were also discussed, respectively. The results show that the characteristics of VOCs in cities are highly related to their industrial structure and GDP. Generally, areas with high AQI values are accompanied by high VOC concentrations. Alkanes and halocarbons were the most abundant VOCs in the atmospheric environment in the nine prefecture-level cities, accounting for 24.5~61.6% and 15.6~23.6% of total VOC concentration, respectively. The MIR method was used to analyze the OFP, and olefins contributed the most to ozone formation. Among the nine cities located in Sichuan, Dazhou was found to be the city with the highest OFP value (1191.49μg/m3).

Plants are exposed to complex interactions with belowground organisms, yet how they differentiate between mutualistic and pathogenic fungi before physical contact remains largely unknown. We exposed the roots of young Populusxcanescens to volatile organic compounds (VOCs) emitted by either a pathogenic (Heterobasidion annosum), a saprotrophic (Postia placenta), or an ectomycorrhizal (Laccaria bicolor) fungus. VOC analysis of the shared rhizosphere headspace and leaf emissions revealed that poplar plants could perceive and respond to fungal identity solely through airborne cues. The root-zone headspace contained fungus-specific sesquiterpene fingerprints that remained similar after three and six weeks of co-cultivation: Pathogen-derived VOCs induced constant high sesquiterpene emissions from the root-zone, whereas mycorrhiza caused low but targeted emissions of specific sesquiterpenes. In contrast, saprotrophic VOCs caused a temporal shift in root-zone VOC pattern, with increased sesquiterpene emissions after six weeks. Fungal VOC exposure also altered leaf VOC emissions, enriching alkanes, esters and monoterpenes. Initially, leaf VOC emissions were fungal lifestyle-specific but they converged over time, indicating systemic signal integration of belowground signals. These findings demonstrate that trees can discriminate "friend-versus-foe" through VOCs alone, extending pattern-recognition theory beyond contact-dependent cues. Multivariate analyses suggested organ-specific chemical strategies: roots function as chemosensors decoding fungal volatilomes, while systemic adjustments shape aboveground VOC profiles. Understanding the plant response to fungal VOCs may offer potential for developing early pathogen diagnostics and further elucidate the volatile-mediated plant-fungal interactions.

Wood inspection and durability testing of wood against microorganisms, as fungi, play an important role in forestry and wood-related material industries. An efficient testing method is required in order to facilitate inspections and to provide the accurate and precise assessment process. Monitoring volatile organic compounds (VOCs) released from wood substrates and from fungal metabolisms are marker compounds of the wood condition, i.e., indicating the type and stage of fungal infection. Insect antennae, which are recognised for their high sensitivity and selectivity in odour perception, are an alternative method for wood testing. On the basis of intact insect antenna biosensor it is possible to monitor wood released VOCs with high selectivity. This technique can be a complement to the traditional wood testing methods, providing a high throughput and non-destructive method. This work was begun with the investigation of VOCs released from four different types of samples with gas chromatography-mass spectrometry. Firstly, VOCs from beech wood (Fagus sylvatica) infected with three wood rotting fungi; Trametes versicolor, Poria placenta, and Gloeophyllum trabeum were analysed. These fungi are commonly used in the durability testing of wood against microorganisms. The VOCs released from the fungal-infected beech showed species specific volatile patterns. The volatiles were grouped to five- and to eight- carbon (C5-C8) containing compounds and terpenoids. 1-Octen-3-ol, 3-octanone, and 3-octanol (C8-compounds) were commonly present in all samples, while terpenoids were species specific. α- and β-Barbatene were characteristic of T. versicolor-infected beech, protuillud-6-ene was characteristic of G. trabeum-infected beech, and daucene was characteristic of P. placenta-infected beech. Secondly, VOCs released from the minimally insect-colonised fruiting body (<10%) and fully insect-colonised fruiting body (~100%) of Trametes gibbosa were identified. The minimally insect-colonised fruiting body released 1-octen-3-ol, the typical fungal odour, at almost 20 times higher than in fully insect-colonised fruiting body. Thirdly, VOCs released during the fruiting body development of the ink-cap Coprinopsis cinerea, from the stage of mycelium to fruiting body autolysis, were studied. VOCs patterns of C. cinerea were specifically altered by the developmental stages. 1-Octen-3-ol and 3-octanone were largely released during primodia formation and were gradually reduced in amount in later developmental stages. The terpenoids β-himachalene and cuparene drastically increased when the C. cinerea stipe elongated and became mature. Finally, the volatiles released during fruiting bodies autolysis of C. cinerea and other two ink-cap decomposing fungi (Coprinus comatus, Coprinopsis atramentaria), were investigated. In all three cases, N-containing and S-containing compounds were additionally released during the autolytic stage. The fungivorous beetle Cis boleti (Coloptera: Ciidae) and the fungal associated fly Suillia mikii (Diptera: Heleomizydae) were chosen for examining their olfactory perception since their life cycles are strongly related to fungi. For instance, C. boleti preferentially colonises fungi from the genus Trametes and S. mikii purposely land on the ink-cap fungi at a specific developmental stage. Gas chromatography-mass spectrometry with parallel electroantennographic detection was employed to demonstrate that both insect species are able to perceive the typical fungal odour 1-octen-3-ol with high selectivity and sensitivity. In addition, behavioural tests of C. boleti showed that this insect is able to discriminate the enantiomers of 1-octen-3-ol, where the female beetles were significantly more attracted to the (S)-(+) enantiomer at lower doses than male beetles. The fly S. mikii reproducibly responded to the VOCs 1-undecene, 2-butanone, and dimethyl trisulfide, released from the autolysis fruiting bodies of the ink-cap fungi. The C. boleti antenna perceived the typical fungal odour, 1-octen-3-ol, with high selectivity and sensitivity of down to 5 ng ml-1 in air. The antenna life time lasted up to one day. Consequently, as a proof of principle C. boleti antenna was used as a biocomponent in a biosensor system for testing beech wood samples infected by T. versicolor. The biosensor system using the superposition method in combination with a recalibration system was adopted. In this configuration C. boleti antenna yielded reproducible responses to the fungal marker volatile compound released from fungal-infected beech wood. Altogether these results lead to a promising possibility to set up a biosensor based on intact antenna as a highly sensitive and selective testing method for wood durability against decay fungi.