Synthesis Of Volatile Compounds Research Articles

Molecular Analysis of Volatile Metabolites Synthesized by Candida albicans and Staphylococcus aureus in In Vitro Cultures and Bronchoalveolar Lavage Specimens Reflecting Single- or Duo-Factor Pneumonia.

Current microbiological methods for pneumonia diagnosis require invasive specimen collection and time-consuming analytical procedures. There is a need for less invasive and faster methods to detect lower respiratory tract infections. The analysis of volatile metabolites excreted by pathogenic microorganisms provides the basis for developing such a method. Given the synergistic role of Candida albicans in increasing the virulence of pathogenic bacteria causing pneumonia and the cross-kingdom metabolic interactions between microorganisms, we compare the emission of volatiles from Candida albicans yeasts and the bacteria Staphylococcus aureus using single and mixed co-cultures and apply that knowledge to human in vivo investigations. Gas chromatography-mass spectrometry (GC-MS) analysis resulted in the identification of sixty-eight volatiles that were found to have significantly different levels in cultures compared to reference medium samples. Certain volatiles were found in co-cultures that mainly originated from C. albicans metabolism (e.g., isobutyl acetate), whereas other volatiles primarily came from S. aureus (e.g., ethyl 2-methylbutyrate). Isopentyl valerate reflects synergic interactions of both microbes, as its level in co-cultures was found to be approximately three times higher than the sum of its amounts in monocultures. Hydrophilic-lipophilic-balanced (HLB) coated meshes for thin-film microextraction (TFME) were used to preconcentrate volatiles directly from bronchoalveolar lavage (BAL) specimens collected from patients suffering from ventilation-associated pneumonia (VAP), which was caused explicitly by C. albicans and S. aureus. GC-MS analyses confirmed the existence of in vitro-elucidated microbial VOCs in human specimens. Significant differences in BAL-extracted amounts respective to the pathogen-causing pneumonia were found. The model in vitro experiments provided evidence that cross-kingdom interactions between pathogenic microorganisms affect the synthesis of volatile compounds. The TFME meshes coated with HLB particles proved to be suitable for extracting VOCs from human material, enabling the translation of in vitro experiments on the microbial volatilome to the in vivo situation involving infected patients. This indicates the direction that should be taken for further clinical studies on VAP diagnosis based on volatile analysis.

Identification and variation of specific volatile compounds during fruit development and postharvest stage in Japanese apricot (Prunus mume Sieb. et Zucc.) fruit

AbstractFruit aroma of Japanese apricot is distinct, and the specific volatile compounds are not clearly known during fruit development and during post‐harvest stage. This study therefore aimed to explore the volatile compounds present during these stages. The volatile compounds were analysed by headspace solid‐phase microextraction and gas chromatography–mass spectrometry. OAV, PCA and electronic nose techniques were used to determine the characteristic aroma components. Enzyme‐linked immunoassay (ELISA) was also applied to determine the activity of enzymes. The results showed that in the cultivars ‘Xiyeqing’ a total of 52 components that included 20 terpenes, 15 aldehydes, 9 esters, 3 ketones and 5 other substances were detected during fruit development and post‐harvest stage. While in the cultivar ‘Xiaoyezhugan’ a total of 49 components that included 25 terpenes, 7 aldehydes, 11 esters, 1 alcohol, 3 ketones and 2 other substances were also detected during fruit development and post‐harvest stage. We concluded that the characteristic volatile compounds of mature Japanese apricot fruit were (+)‐limonene, linalool, damascenone, β‐damascenone and nonanal, finding the basis for the fruity, floral and sweet aroma of the Japanese apricot fruit. Further analysis indicated that low temperature inhibited the synthesis of esters and terpenes, and dark conditions were more favourable to the synthesis of volatile compounds than light conditions. Short‐term storage of Japanese apricot fruit at room temperature and dark conditions was conducive for the maintenance of volatile compounds, and low‐temperature storage was the most destructive to the fruit volatile compounds. These findings form a theoretical foundation for exploring the specific volatile compound of Japanese apricot and helped to determine the optimal storage condition of post‐harvest stage for Japanese apricot fruit.

Effect of Light Conditions, Trichoderma Fungi and Food Polymers on Growth and Profile of Biologically Active Compounds in Thymus vulgaris and Thymus serpyllum.

The research investigates the influence of different lighting conditions and soil treatments, in particular the application of food polymers separately and in combination with spores of Trichoderma consortium, on the growth and development of herbs-Thymus vulgaris and Thymus serpyllum. The metabolic analysis focuses on detecting changes in the levels of biologically active compounds such as chlorophyll a and b, anthocyanins, carotenoids, phenolic compounds (including flavonoids), terpenoids, and volatile organic compounds with potential health-promoting properties. By investigating these factors, the study aims to provide insights into how environmental conditions affect the growth and chemical composition of selected plants and to shed light on potential strategies for optimising the cultivation of these herbs for the improved quality and production of bioactive compounds. Under the influence of additional lighting, the growth of T. vulgaris and T. serpyllum seedlings was greatly accelerated, resulting in an increase in shoot biomass and length, and in the case of T. vulgaris, an increase in carotenoid and anthocyanin contents. Regarding secondary metabolites, the most pronounced changes were observed in total antioxidant capacity and flavonoid content, which increased significantly under the influence of additional lighting. The simultaneous or separate application of Trichoderma and food polymers resulted in an increase in flavonoid content in the leaves of both Thymus species. The increase in terpenoid content under supplemental light appears to be related to the presence of Trichoderma spores as well as food polymers added to the soil. However, the nature of these changes depends on the thyme species. Volatile compounds were analysed using an electronic nose (E-nose). Eight volatile compounds (VOCs) were tentatively identified in the vapours of T. vulgaris and T. serpyllum: α-pinene, myrcene, α-terpinene, γ-terpinene; 1,8-cineole (eucalyptol), thymol, carvacrol, and eugenol. Tendencies to increase the percentage of thymol and γ-terpinene under supplemental lighting were observed. The results also demonstrate a positive effect of food polymers and, to a lesser extent, Trichoderma fungi on the synthesis of VOCs with health-promoting properties. The effect of Trichoderma and food polymers on individual VOCs was positive in some cases for thymol and γ-terpinene.

The genome of Citrus australasica reveals disease resistance and other species specific genes

BackgroundThe finger lime (Citrus australasica), one of six Australian endemic citrus species shows a high natural phenotypic diversity and novel characteristics. The wide variation and unique horticultural features have made this lime an attractive candidate for domestication. Currently no haplotype resolved genome is available for this species. Here we present a high quality, haplotype-resolved reference genome for this species using PacBio HiFi and Hi-C sequencing.ResultsHifiasm assembly and SALSA scaffolding resulted in a collapsed genome size of 344.2 Mb and 321.1 Mb and 323.2 Mb size for the two haplotypes. The nine pseudochromosomes of the collapsed genome had an N50 of 35.2 Mb, 99.1% genome assembly completeness and 98.9% gene annotation completeness (BUSCO). A total of 41,304 genes were predicted in the nuclear genome. Comparison with C. australis revealed that 13,661 genes in pseudochromosomes were unique in C. australasica. These were mainly involved in plant-pathogen interactions, stress response, cellular metabolic and developmental processes, and signal transduction. The two genomes showed a syntenic arrangement at the chromosome level with large structural rearrangements in some chromosomes. Genetic variation among five C. australasica cultivars was analysed. Genes related to defense, synthesis of volatile compounds and red/yellow coloration were identified in the genome. A major expansion of genes encoding thylakoid curvature proteins was found in the C. australasica genome.ConclusionsThe genome of C. australasica present in this study is of high quality and contiguity. This genome helps deepen our understanding of citrus evolution and reveals disease resistance and quality related genes with potential to accelerate the genetic improvement of citrus.

Genomic analysis reveals genes that encode the synthesis of volatile compounds by a Bacillus velezensis-based biofungicide used in the treatment of grapes to control Aspergillus carbonarius

Fungal control strategies based on the use of Bacillus have emerged in agriculture as eco-friendly alternatives to replace/reduce the use of synthetic pesticides. Bacillus sp. P1 was reported as a new promising strain for control of Aspergillus carbonarius, a known producer of ochratoxin A, categorized as possible human carcinogen with high nephrotoxic potential. Grape quality can be influenced by vineyard management practices, including the use of fungal control agents. The aim of this study was to evaluate, for the first time, the quality parameters of Chardonnay grapes exposed to an antifungal Bacillus-based strategy for control of A. carbonarius, supporting findings by genomic investigations. Furthermore, genomic tools were used to confirm that the strain P1 belongs to the non-pathogenic species Bacillus velezensis and also to certify its biosafety. The genome of B. velezensis P1 harbors genes that are putatively involved in the production of volatiles and hydrolytic enzymes, which are responsible for releasing the free form of aroma compounds. In addition to promote biocontrol of phytopathogenic fungi and ochratoxins, the treatment with B. velezensis P1 did not change the texture (hardness and firmness), color and pH of the grapes. Heat map and hierarchical clustering analysis (HCA) of volatiles evaluated by GC/MS revealed that Bacillus-treated grapes showed higher levels of compounds with a pleasant odor descriptions such as 3-hydroxy-2-butanone, 2,3-butanediol, 3-methyl-1-butanol, 3,4-dihydro-β-ionone, β-ionone, dihydroactinidiolide, linalool oxide, and β-terpineol. The results of this study indicate that B. velezensis P1 presents desirable properties to be used as a biocontrol agent.

Study on simulation effect of physical and chemical characteristics of sausage by sausage model system.

The incorporation of Staphylococcus xylosus in sausage production is hypothesized to affect various physicochemical properties and flavor profiles of sausages. This study aimed to evaluate the simulation of these features in a sausage model and establish its applicability for in vitro studies. Both a control and an experimental model, inclusive of Staphylococcus xylosus, were assessed for changes in physicochemical indexes (pH and water activity, Aw) and the concentration of flavoring components (esters and aldehydes). Thiobarbituric acid reactive substances (TBARS) values were also measured to evaluate lipid oxidation. The introduction of Staphylococcus xylosus resulted in no significant changes in pH and Aw between the sausage and the model. However, there was a considerable increase in the content of volatile flavor compounds, specifically esters and aldehydes, in the experimental groups compared to the control. Additionally, the TBARS values in experimental groups were significantly lower than those in the control group at the end of the testing period. The findings indicate that Staphylococcus xylosus plays a critical role in enhancing the flavor profile of sausages through the increased synthesis of volatile compounds and inhibiting fat oxidation. The sausage model effectively simulated the physicochemical and flavor index responses, demonstrating its potential utility for further in vitro research on sausage fermentation and preservation techniques.

Mechanism of Salt Tolerance and Plant Growth Promotion in Priestia megaterium ZS-3 Revealed by Cellular Metabolism and Whole-Genome Studies

Approximately one-third of agricultural land worldwide is affected by salinity, which limits the productivity and sustainability of crop ecosystems. Plant-growth-promoting rhizobacteria (PGPR) are a potential solution to this problem, as PGPR increases crop yield through improving soil fertility and stress resistance. Previous studies have shown that Priestia megaterium ZS-3(ZS-3) can effectively help plants tolerate salinity stress. However, how ZS-3 regulates its metabolic adaptations in saline environments remains unclear. In this study, we monitored the metabolic rearrangement of compatibilisers in ZS-3 and combined the findings with genomic data to reveal how ZS-3 survives in stressful environments, induces plant growth, and tolerates stress. The results showed that ZS-3 tolerated salinity levels up to 9%. In addition, glutamate and trehalose help ZS-3 adapt to osmotic stress under low NaCl stress, whereas proline, K+, and extracellular polysaccharides regulate the osmotic responses of ZS-3 exposed to high salt stress. Potting experiments showed that applying the ZS-3 strain in saline and neutral soils could effectively increase the activities of soil acid phosphatase, urease, and invertase in both soils, thus improving soil fertility and promoting plant growth. In addition, strain ZS-3-GFP colonised the rhizosphere and leaves of Cinnamomum camphora well, as confirmed by confocal microscopy and resistance plate count analysis. Genomic studies and in vitro experiments have shown that ZS-3 exhibits a variety of beneficial traits, including plant-promoting, antagonistic, and other related traits (such as resistance to saline and heavy metal stress/tolerance, amino acid synthesis and transport, volatile compound synthesis, micronutrient utilisation, and phytohormone biosynthesis/regulatory potential). The results support that ZS-3 can induce plant tolerance to abiotic stresses. These data provide important clues to further reveal the interactions between plants and microbiomes, as well as the mechanisms by which micro-organisms control plant health.

Discrimination of internal browning in pineapple during storage based on changes in volatile compounds

Internal browning (IB) is a physiological disorder without external symptoms of postharvest pineapples, but whether and how IB influences pineapple volatiles remain unknown. We examined eigenvalues of volatiles in ‘Comte de Paris’ pineapples with or without IB using electronic nose (E-nose) and gas chromatography-mass spectrometry (GC–MS). Correlation coefficients between the responses of E-nose sensors S7 and S9 and IB were 0.836 and 0.804, respectively. The multilayer perceptron neural network and radial basis function neural network models classified IB degree with accuracy of 94.77% and 91.67%. GC–MS analysis revealed 30 volatile substances upregulated in pineapple with IB compared to those without, of which 15 were esters. IB regulated volatile compound synthesis through the lipoxygenase pathway which involved lipoxygenase, pyruvate decarboxylase 1, alcohol dehydrogenases, acyl-CoA oxidase 1, and alcohol acyltransferase genes and their related enzymes. These results suggested that volatiles regulated by IB could be used to discriminate IB severity in pineapples.

Response of heritage and modern wheat varieties to altitude induced stresses by synthesis of volatile compounds. A multivariate statistical analysis

The genotype × altitude interactive effect on crops quality is a crucial topic for researchers who face the challenge of climate changes. In this study, three common and durum wheat, including two old varieties, were grown for three years in different organic farms sited at three altitudes in the Abruzzo region (Italy). Volatile organic compounds (VOCs), along with agronomic yield and protein content were analysed. Genotype × altitude interaction resulted always statistically significant and altitude of cultivation negatively affected yield and protein content. A multivariate statistical approach permitted to unravel the most important VOCs useful to predict the effect of altitude of cultivation on wheat species. Durum wheat synthetized a higher number of VOCs than common wheat as a response to altitude-induced stress. Elevation of cultivation determined also a strong variety-dependent adaptative response, with characteristic VOCs patterns for any specific wheat. Heritage wheat emitted a higher number of volatiles in response to altitude changes, with (E)-2-Nonenal being a putative marker of these varieties. These results reveal the complexity behind the plants system defence against abiotic and biotic stresses induced by altitude and could open new perspectives for the study of the dependence of wheat production and quality on the territory.

Isolation, Evaluation and Characterization of Indigenous Trichoderma spp. for the Management of Wilt of Chickpea Caused by Fusarium oxysporum f. sp. ciceris

Background: Fusarium oxysporum f. sp. ciceris causing chickpea wilt, a significant soil-borne disease that causes severe crop losses. Trichoderma spp. is a diverse fungal bio-control agent with the ability to limit plant disease growth through a variety of ways. The goal of this work is to assess the efficiency of indigenous Trichoderma spp. isolated from chickpea rhizosphere from different North Eastern districts of Karnataka against the wilt pathogen in vitro, as well as to investigate the cultural and morphological aspects of isolates. Methods: Dual culture approach was used to investigate the antagonistic potential of Trichoderma isolates and inverted plate technique was used to examine the synthesis of volatile compounds from Trichoderma spp. The isolates were cultured on potato dextrose agar medium for cultural characterization. Under a microscope, morphological characters were observed. Result: Twenty Trichoderma isolates were reported to be effective against F. oxysporum f. sp. ciceris, preventing mycelial growth by 48.52 to 91.85%. All the isolates produced significant amount of volatile compounds that inhibited F. oxysporum f. sp. ciceris growth by 2.59 to 72.22%. At 72 hours after incubation, the isolates had different radial mycelium growth and formed fluffy and elevated colony growth, with colony margins ranging from smooth to wavy.

Evolution of the Volatile Organic Compounds, Phenols and Antioxidant Capacity during Fruit Ripening and Development of Rubus ulmifolius Schott Fruits

Nowadays, a growing interest in consumers’ fruit with a high content of health-promoting compounds has been observed. In this sense, wild berries have received special attention based on their high accumulation of phenolic compounds, as well as their characteristic and pleasant aroma. In this work, we characterize the color development, antioxidant capacity, phenolic contents, and volatile profile of Rubus ulmifolius Schott fruit at different ripening stages during two seasons on the same orchard. Four stages were established based on the color parameter, which was consistent with changes in the weight and size of the fruit. In addition, total phenolic and flavonoid content showed a decrease during the fruit ripening, in contrast with the total anthocyanins content that increased at the final stages of ripening. In addition, the antioxidant capacity was evaluated through two approaches: FRAP and DPPH, which consistently displayed higher levels at the final stages in the two different seasons. Finally, the VOCs analysis showed an active synthesis of volatile compounds during the late stage of ripening, with alcohols being the most abundant compounds for each ripening stage. These results allow us to propose a classification of different ripening stages of the wild blackberry to have a better knowledge of this interesting fruit with higher healthy- and nutraceutical compounds.

Evaluation of the Volatile Composition and Sensory Behavior of Habanero Pepper during Lactic Acid Fermentation by L. plantarum

Habanero pepper is recognized for its appealing aroma and flavor. Lactic acid fermentation can improve these sensory properties, especially aroma, by the synthesis of volatile compounds, which might also increase the consumer preference. Thus, the aim of this research was to compare the volatile composition as well as different sensory parameters such as preference and emotions related to the lactic acid fermentation of Habanero pepper by two strains (wild and commercial) of Lactiplantibacillus plantarum. A multiple factor ANOVA was used to compare the volatile composition with different fermentation times and strains. The results demonstrated that the interaction between the strain and fermentation time had significant effects on the volatile compound production that includes 1-hexanol, cis-3-hexenyl hexanoate, linalool, and 3,3 dimethyl-1-hexanol while only time influenced the production of trans-2-hexen-1-al. The wild strain (WIL) at 48 h of fermentation produced the highest concentration of 3,3 dimethyl-1-hexanol and trans-2-hexen-1-al. On the other hand, the commercial strain (COM) presented the highest concentration of 1-hexanol and cis-3-hexenyl hexanoate with a 72 h fermentation. The most preferred sample was that fermented by WIL for 48 h for the attribute of odor, while for taste, the most preferred sample was that fermented for 72 h with COM.

Fermentation Conditions Affect the Synthesis of Volatile Compounds, Dextran, and Organic Acids by Weissella confusa A16 in Faba Bean Protein Concentrate.

Fermentation with Weissella confusa A16 could improve the flavor of various plant-based sources. However, less is known about the influence of fermentation conditions on the profile of volatile compounds, dextran synthesis and acidity. The present work investigates the synthesis of potential flavor-active volatile compounds, dextran, acetic acid, and lactic acid, as well as the changes in viscosity, pH, and total titratable acidity, during fermentation of faba bean protein concentrate with W. confusa A16. A Response Surface Methodology was applied to study the effect of time, temperature, dough yield, and inoculum ratio on the aforementioned responses. Twenty-nine fermentations were carried out using a Central Composite Face design. A total of 39 volatile organic compounds were identified: 2 organic acids, 7 alcohols, 8 aldehydes, 2 alkanes, 12 esters, 3 ketones, 2 aromatic compounds, and 3 terpenes. Long fermentation time and high temperature caused the formation of ethanol and ethyl acetate and the reduction of hexanal, among other compounds linked to the beany flavor. Levels of dextran, acetic acid, and lactic acid increased with increasing temperature, time, and dough yield. Optimal points set for increased dextran and reduced acidity were found at low temperatures and high dough yield. Such conditions would result in hexanal, ethyl acetate and ethanol having a relative peak area of 35.9%, 7.4%, and 4.9%, respectively.

Coffee's carbohydrates. A critical review of scientific literature

Only two species have gained economic importance in coffee production: Coffea arabica L. (Arabica coffee) & Coffea canephora Pierre ex A. Froehner var. Robusta, with 65 and 35% of world production attributed to C. arabica http://wsx5customurl.comL. & C. canephora P. respectively. In general, it is estimated that 6 mt of fresh and ripe fruits produce approximately 1 mt of raw and dry grains. The grain endosperm is mainly composed of cellulose, hemicelluloses, proteins, minerals and lipids, but starch and tannins are absent. However, the seed's chemical composition of C. arabica and C. canephora, before roasting, differs concerning their primary and secondary metabolites content, which serve as precursors for the synthesis of volatile compounds during the roasting process. For this reason, there are marked organoleptic differences between both species' roasted and ground grain. However, the evidence suggests that such differences can also be attributed to other factors since coffees grown in cool, highland areas generally have better sensory attributes than their counterparts grown in hot, lowland areas. It has been speculated that environmental conditions in cool, highland areas induce the slow accumulation of primary and secondary metabolites during the endosperm development resulting in sensorial differences after roasting. This essay focuses on the study of coffee beans' carbohydrates (primary metabolites) before and after roasting, their influence on cup quality, biosynthesis and differences linked to the involved species, their metabolism, solubility and extraction, as well as a discussion on the analytical techniques used for its determination. Keywords: sucrose synthase, sucrose phosphate phosphatase, sucrose phosphate synthase, aploplasm, cytoplasm, Manan synthase, Galactosyl transferase.

Effects of the repression of GIGANTEA gene StGI.04 on the potato leaf transcriptome and the anthocyanin content of tuber skin

BackgroundGIGANTEA (GI) is a plant-specific, circadian clock-regulated, nuclear protein with pleiotropic functions found in many plant species. This protein is involved in flowering, circadian clock control, chloroplast biogenesis, carbohydrate metabolism, stress responses, and volatile compound synthesis. In potato (Solanum tuberosum L.), its only role appears to be tuber initiation; however, based on findings in other plant species, we hypothesised that the function of GI in potatoes is not restricted only to tuberisation.ResultsTo test this hypothesis, the expression of a GI gene in the commercial potato cultivar ‘Désirée’ was repressed, and the effects of repression at morphological and transcriptome level were investigated. Previously, two copies of GI genes in potato were found. A construct to reduce the mRNA levels of one of these genes (StGI.04) was assembled, and the effects of antisense repression were studied in greenhouse-grown plants. The highest level of repression reached around 50%. However, this level did not influence tuber formation and yield but did cause a reduction in tuber colour. Using high-performance liquid chromatography (HPLC), significant reductions in cyanidin 3,5-di-O-glucoside and pelargonidin 3,5-di-O-glucoside contents of tuber peels were detected. Anthocyanins are synthesized through a branch of the phenylpropanoid pathway. The transcriptome analysis indicated down-regulation in the expression of PHENYLALANINE AMMONIA LYASE (PAL), the LEUCOANTHOCYANIDIN OXIDISING enzyme gene LDOX, and the MYB-RELATED PROTEIN Hv1 (MYB-Hv1), a transcription factor coding gene, which is presumably involved in the regulation of flavonoid biosynthesis, in the leaves of a selected StGI.04-repressed line. Furthermore, alterations in expression of genes affecting the circadian clock, flowering, starch synthesis, and stress responses were detected in the leaves of the selected StGI.04-repressed line.ConclusionsWe tested the effects of antisense repression of StGI.04 expression in potatoes and found that as with GI in other plant species, it influences the expression of the key genes of the circadian clock, flowering, starch synthesis, and stress responses. Furthermore, we detected a novel function of a GI gene in influencing the anthocyanin synthesis and potato tuber skin colour.

Low-waste technology for the production of bioethanol from sorghum grain: Comparison of Zymomonas mobilis and Saccharomyces cerevisiae in fermentation with stillage reusing

Zymomonas mobilis and Saccharomyces cerevisiae have been used for simultaneous saccharification and fermentation of sorghum grain with the reuse of the stillage. This study investigated the effects of replacing half the water by a stillage liquid fraction on ethanol yield and volatile compound synthesis. Studies have shown that Z. mobilis is more efficient in ethanol production (55.96–61.48 g/L) than S. cerevisiae (55.26–58.38 g/L). Additionally, Z. mobilis had the advantage of a shorter fermentation time (48 h) and lower fermentation temperature (35 °C) than distillery yeast. No relationship was observed between successive stillage reusing and ethanol content. Reusing the liquid fraction of the stillage did not increase the amount of volatile compounds identified in the raw distillates. Significant differences were observed in the volatile compounds profile of bacterial and yeast raw distillates. Acetaldehyde was the dominant compound in bacterial raw distillates, whereas 3-methylbutan-1-ol was the dominant compound in yeast raw distillates. The characteristic of Z. mobilis was the production of fewer (4.31–6.03 g/L spirit 100%) volatile compounds compared to yeast (4.04–7.44 g/L spirit 100%). The fermentation process reusing the liquid part of the stillage made it possible to reduce process water consumption and waste generation in bioethanol production from sorghum grain. In addition, Z. mobilis made ethanol production from sorghum grain grown in Eastern Europe more beneficial.

Olfactory response of Trichogramma pretiosum (Hymenoptera: Trichogrammatidae) to volatiles induced by transgenic maize.

Plants not only respond to herbivorous damage but adjust their defense system after egg deposition by pest insects. Thereby, parasitoids use oviposition-induced plant volatiles to locate their hosts. We investigated the olfactory behavioral responses of Trichogramma pretiosum Riley, 1879 (Hymenoptera: Trichogrammatidae) to volatile blends emitted by maize (Zea mays L.) with singular and stacked events after oviposition by Spodoptera frugiperda Smith, 1797 (Hymenoptera: Trichogrammatidae) moths. Additionally, we examined possible variations in gene expression and on oviposition-induced volatiles. We used a Y-tube olfactometer to test for the wasp responses to volatiles released by maize plants oviposited by S. frugiperda and not-oviposited plants. Using the real-time PCR technique (qRT-PCR), we analyzed the expression of lipoxygenase and three terpene synthases genes, which are enzymes involved in the synthesis of volatile compounds that attract parasitoids of S. frugiperda. Olfactometer tests showed that T. pretiosum is strongly attracted by volatiles from transgenic maize emitted by S. frugiperda oviposition (VTPRO 3, more than 75% individuals were attracted). The relative expression of genes TPS10, LOX e STC was higher in transgenic hybrids than in the conventional (isogenic line) hybrids. The GC-MS analysis revealed that some volatile compounds are released exclusively by transgenic maize. This study provides evidence that transgenic hybrids enhanced chemical cues under oviposition-induction and helped to increase T. pretiosum efficiency in S. frugiperda control. This finding shows that among the evaluated hybrids, genetically modified hybrids can improve the biological control programs, since they potentialize the egg parasitoid foraging, integrating pest management.

Influence of the fatty acid profile on the volatile components of virgin olive oil subjected to thermal stress.

Virgin olive oil (VOO) is greatly appreciated for its organoleptic features, which can be ascribed mainly to the presence of very chemically diverse volatile components. It is well known that the VOO volatile fraction depends strongly on different aspects, which encompass genetic, agronomic, processing, and post-processing factors. In this research, we developed a method for the qualitative and semiquantitative determination of volatile components in VOOs subjected to thermal stress by headspace extraction online coupled to gas chromatography-mass spectrometry (HS-GC-MS). The method was applied to 100 extra-virgin olive oil (EVOO) samples, which led to the tentative identification of 52 volatile components, including 12 alcohols, 17 aldehydes, three ketones, one ether, two furans, two carboxylic acids, and 15 hydrocarbons. The method was used to study the cultivar effect and the main biochemical pathways involved in the synthesis of volatile compounds, with special emphasis on those formed by degradation of unsaturated fatty acids (FAs). Principal component analysis (PCA), explaining 76.7% of the total variability, showed that the volatile profile of EVOOs subjected to thermal stress allowed discriminating samples from different cultivars. Volatiles detected in EVOOs subjected to thermal stress with the highest contribution to discrimination between the selected cultivars were correlated with the concentration of the three main FAs in VOO, namely oleic, linoleic, and linolenic acids. The FA profile seems to be especially relevant to explain the concentration of certain volatile compounds with direct incidence on the organoleptic properties. © 2021 Society of Chemical Industry.

Evaluation of indigenous non-Saccharomyces cider yeasts for use in brewing

The non-Saccharomyces yeasts represent a great richness for the production of new and different types of beers. In this study, the role of eight yeast strains (Saccharomycodes ludwigii, Metchnikowia pulcherrima, Hanseniaspora uvarum, Hanseniaspora osmophila and Brettanomyces bruxellensis) isolated from Asturian cider and belonging to five unconventional species was evaluated. None of the strains could ferment the main wort sugars (maltose and maltotriose). Beers produced by S. ludwigii strains showed the highest ethanol content (21.6 g/L) and interestingly high levels of fusel alcohols, fatty esters and isoamyl acetate. Strains of B. bruxellensis were the only ones that produced ethyl phenols and they also generated the highest concentration of fatty acids and their ethyl esters. Sucrose was not utilised by Metschnikowia and Hanseniaspora strains, resulting in low ethanol formation (4.7 g/L), although these yeasts differed in terms of their synthesis of volatile compounds. Larger amounts of fatty acid esters were detected in beers fermented by H. osmophyla 10, while H. uvarum 62 produced more 2-phenylethyl acetate and ethyl acetate. M. pulcherrima 301 stands out for its low fermentative capacity and production of volatile compounds. These results show the interest of non-Saccharomyces strains in the production of beers with low alcohol content and their potential use in developing new beer styles in sequential or mixed inoculations with S. cerevisiae strains.

Comparative transcriptome analysis of genes involved in volatile compound synthesis in blueberries (Vaccinium virgatum) during postharvest storage

• Genes involved in postharvest blueberry aroma biosynthesis were characterized. • Increased ethyl acetate was associated with increased PDC activity after harvest. • Postharvest storage modulated terpene synthase (TPS) genes associated with linalool. Transcriptional regulation of aroma formation genes during postharvest storage remains poorly understood in the blueberry. In order to have a better understanding of the transcriptional regulation processes that occur in rabbiteye blueberry during storage and their effect on the volatile composition change, we performed volatile metabolite profiling and transcriptomic analysis. Our study reveals that during postharvest storage, ‘Garden blue’ blueberry volatile composition changed by regulating several secondary metabolic pathways, in particular, by stimulating the expression of pyruvate decarboxylase (PDC) genes, resulting in a high production of ethyl acetate. Postharvest storage also modulated some terpene synthase (TPS) genes associated with linalool production. The concentration of C6 aldehydes and alcohols decreased during the postharvest storage accompanied by lower lipoxygenase (LOX) gene expression. These findings illustrate the molecular and biochemical mechanisms that occur in blueberry during the postharvest storage period, especially with regard to volatile composition changes.