Main Volatile Organic Compounds Research Articles

Changes in chemical properties and microbial communities' composition of a forest litter-based biofertilizer produced through aerated solid-state culture under different oxygen conditions.

Fermented forest litter (FFL) is a bioproduct used as biofertilizer for several decades in Eastern Asia and Latin America. It is locally handcrafted by farmers in anaerobic conditions by fermenting forest litter added with agricultural by-products such as whey, cereal bran, and molasses. The aim of this study was to characterize the FFL process and product through gas and liquid chromatography analyses. It also provides some highlights on the influence of O2 on this solid-state culture. Under anoxic condition, a maximum CO2 production rate (CDPR) of 0.41mL/h∙g dry matter (dm) was reached after 8days. The main volatile organic compounds (VOCs) were ethanol and ethyl acetate, with a production rate profile similar to CDPR. After 21days of culture, no residual sucrose nor lactose was detected. Lactic and acetic acids reached 58.8mg/g dm and 10.2mg/g dm, respectively, ensuring the acidification of the matrix to a final pH of 4.72. A metabarcoding analysis revealed that heterolactic acid bacteria (Lentilactobacillus, Leuconostoc), homolactic acid bacteria (Lactococcus), and yeasts (Saccharomyces, Clavispora) were predominant. Predicted genes in the microbiome confirmed the potential link between detected bacteria and acids and VOCs produced. When O2 was fed to the cultures, final pH reached values up to 8.5. No significant amounts of lactic nor acetic acid were found. In addition, a strong shift in microbial communities was observed, with a predominance of Proteobacteria and molds, among which are potential pathogens like Fusarium species. This suggests that particular care must be brought to maintain anoxic conditions throughout the process.

Micro- and Mesoporous Structural Effects of Beta Zeolites for Volatile Organic Compound Sorption.

To fully exploit pore engineering in the design of more efficient zeolite adsorbents for volatile organic compound (VOC) treatment, the roles of meso- and micropores need to be clarified to provide the theoretical basis and feasible measures. In this work, the three VOC sorption properties of conventional and hierarchical porous beta zeolites were comparatively investigated to study the roles of meso- and micropores. There is a division of functions between micro- and mesopores, with micropores being the main VOC adsorption sites and mesopores greatly enhancing VOC diffusion and adsorbent reusability. On the one hand, micropores should be preserved as much as possible because obtaining mesopores by sacrificing micropores (i.e., alkali treatment) results in 28-60% decreases in adsorption capacities. On the other hand, mesopore introduction is highly desirable, which results in an enhancement of VOC intraparticle diffusion rates by 1.3-2.3 times (at the VOC concentration of 600 ppm) and chlorobenzene adsorption capacity on the 20th cycle increasing from 78% of the initial value to 89 and 93%. The findings may provide valuable information about zeolite-based adsorbents for adsorption removal or recovery of VOCs.

Metabolomics reveals how ethylene‐auxin interaction delays tomato ripening maintaining fruit nutritional and sensorial quality

SummaryThe antagonistic roles of ethylene and auxin are well established, although the exact role of auxin in ripening regulation remains unclear. A metabolomic approach can be a strategy to understand the role of this phytohormone in improving tomato quality. This study used metabolomic approaches to investigate how the interaction between ethylene and auxin affects tomato fruit nutritional and sensorial quality, with a particular emphasis on aroma metabolites. Tomato (Solanum lycopersicum cv. Micro‐Tom) fruits were randomly grouped according to treatment with ethylene (ETHY), auxin (IAA), or both (ETHY + IAA) phytohormones. Fruits without treatment were grouped in CTRL. Ethylene and auxin treatments affected carbohydrates (fructose, sucrose, and glucose), organic acids (citric and malic acids), and amino acids (valine, asparagine, and GABA), with the main volatile organic compounds precursors positively impacting ETHY + IAA aroma compounds. In conclusion, the comparison of metabolome profiles suggests that auxin regulation may overlap the ethylene regulatory system. Furthermore, tomato fruits treated with both phytohormones maintained metabolic profiles similar to those of untreated fruits in delayed ripening conditions, besides the improved tomato aroma.

Brazilian indigenous nonstarter lactic acid bacteria enhance the diversification of volatile compounds in short-aged cheese.

There is growing interest in using autochthonous lactic acid bacteria (LAB) that provide unique sensory characteristics to dairy products without affecting their safety and quality. This work studied the capacity of three Brazilian indigenous nonstarter LABs (NSLAB) to produce biogenic amines (BAs) and evaluated their effect on the volatile organic compounds (VOCs), microbial LAB communities, and physicochemical profile of short-aged cheese. Initially, the strain's potential for biosynthesis of BAs was assessed by PCR and in vitro assays. Then, a pilot-scale cheese was produced, including the NSLAB, and the microbial and VOC profiles were analyzed after 25 and 45 days of ripening. As a results, the strains did not present genes related to relevant BAs and did not produce them in vitro. During cheese ripening, the Lactococci counts were reduced, probably in the production of alcohols and acid compounds by the NSLAB. Each strain produces a unique VOC profile that changes over the ripening time without the main VOCs related to rancid or old cheese. Particularly, the use of the strain Lacticaseibacillus. paracasei ItalPN16 resulted in production of ester compounds with fruity notes. Thus, indigenous NSLAB could be a valuable tool for the enhancement and diversification of flavor in short-aged cheese.

The impact of processing technology on microbial community composition and functional properties of Beninese maize ogi

Traditionally fermented maize starch, called ogi, is produced to prepare akpan, a yoghurt-like street food widely consumed in Benin. Current maize ogi production practices were compared to assess the impact of different processing technologies on the characteristics of the fermented product as a basis to determine best practices. Maize starch slurry samples were collected from processors in five municipalities in southern Benin and analysed before fermentation (starch samples) and after spontaneous fermentation (ogi samples). Four technological pathways for maize starch production were distinguished based on variations in the duration of steeping the grains, which ranged from 6 to 72 h, and whether or not kneading of the wet flour before filtration was practised. Six categories of maize ogi were derived from the four technology groups based on the duration of the fermentation, which lasted from 6 to 24 h. The average pH of maize starch varied from 3.2 to 5.3, with the lowest values for the two technology groups that also had the highest lactate concentrations (9–11.8 g/L). The six maize ogi categories had a pH ranging from 3.1 to 4.0. Viable plate counts of lactic acid bacteria were similar for maize starch samples and for ogi samples, whereas yeast counts showed clear differences. Members of the genera Limosilactobacillus, Lactobacillus, Weissella, Streptococcus and Ligilactobacillus, dominated the bacterial community in maize starch, and were also dominant in maize ogi. The members of the genera dominating the fungal community in maize starch were also dominant in maize ogi, except for Aspergillus and Stenocarpella spp., which decreased in relative abundance by fermentation. The highest total free essential amino acid concentration was 61.6 mg/L in maize starch and 98.7 mg/L in ogi. The main volatile organic compounds in maize starch samples were alcohols, esters, and carboxylic acids, which also prevailed in maize ogi samples. The results indicate that the characteristics of traditional maize ogi depend on the processing technologies used to produce the maize starch before the intentional fermentation into ogi, with no clear-cut connection with the production practices due to high variations between samples from the same technology groups. This revealed the importance of a standardized maize starch production process, which would benefit controlling the starch fermentation and the characteristics of maize ogi. Further research is needed to understand the hidden fermentation during maize starch production for determination of the best practices that support the production of quality maize ogi.

Volatile organic composition of five Rubiaceae species: Insights into their phytochemical diversity

Natural volatile organic compounds (VOCs) obtained from five Rubiaceae plants native to south China, namely Damnacanthus indicus, Hamelia patens, Exallage chrysotricha, Psychotria serpens, and Spermacoce pusilla, were isolated and characterized in this study. The analysis revealed that each plant contained 71, 57, 80, 73, and 70 volatile organic chemical compounds, respectively. The main VOCs shared by five plants was palmitate (10.20%–36.26%). Methyl salicylate, caryophyllene oxide, tetradecanoic acid, 6,10,14-trimethyl-2-pentadecanone, pentadecanoic acid, pentacosane, pentadecanal, nonanal, hexadecanoic acid methyl ester, phytol, linalool, and (E)-β-ionone were shared by at least 4 Rubiaceae plants in this study. Besides, each of the five plants has its main components as follows: 12.81% ethyl linoleate and 6.13% (E)-13-octadecenoic acid for D. indicus; 35.17% methyl salicylate for H. patens; 9.50% (Z, Z)-9,12-octadecadienoic acid and 7.56% endo-borneol for E. chrysotricha; 13.93% methyl salicylate for P. serpens; 6.19% humulene and 6.08% humulene oxide II for S. pusilla. This research provides insights into the phytochemical diversity and classification of Rubiaceae plants, laying a solid foundation for future natural product development in the Rubiaceae family.

Investigation on dynamic VOC production from industrial, high solids content emulsion polymerizations

Volatile Organic Compounds (VOC) pose a serious threat to human health and the environment. Unfortunately, many processes from fine chemistry involve VOCs as reagents, solvents, products or by-products. International standards and market requirements keep asking for lower VOC content in commercial goods, with the final aim of VOC-free products. Accomplishing such a task is a challenge because VOCs, due to their high vapour pressure, are hard to remove with traditional industrial methods, such as vacuum stripping or absorption. For this reason, it is important to know and understand how VOCs evolve throughout a chemical reaction. In this field, adhesives, which are usually developed exploiting polymerizations, represent an interesting subject, due to the complexity of their industrial synthesis: VOCs appear as reagents (monomers), conversion enhancers (post-polymerization), and by-products (hydrolysis and small chains). In this work, a study on the evolution and content of VOCs of an industrial recipe involving emulsion polymerizations is carried out. The industrial recipe is characterized by high solids content (about 70% w/w) and is mainly composed of 2-ethylhexyl acrylate (up to 50% w/w), anionic and nonionic surfactants. The evolution of the main VOCs found under different working conditions is discussed. The main VOCs found are acetaldehyde, acetone, t-butanol, vinyl acetate, butanol, methyl-methacrylate, butyl acrylate, 2-ethyl-exyl-alcohol, 2-ethyl-exyl-acetate and 2-ethyl-exyl-acrylate.

High-solution emission characters and health risks of volatile organic compounds for sprayers in automobile repair industries.

The increasing automobile repair industries (ARIs) with spray facilities have become an important volatile organic compound (VOC) pollution source in China. However, the VOC health risk assessment for long-term exposure in ARIs has not been well characterized. In this study, though sampled VOCs from 51 typical ARIs in Beijing, the relationship between emission patterns, average daily exposure concentrations (EC), and health risks was comprehensively analyzed with the health assessment method. Results showed that concentrations of 117 VOCs from the samples ranged from 68.53 to 19863.32 μg·m-3, while the ARI operator's daily VOC inhalation EC was 11.24-1460.70 μg·m-3. The organic VOC (OVOC) concentration accounted for 73.16 ~ 94.52% in the solvent-based paint workshops, while aromatics were the main VOC component in water-based paint spraying (WPS) workshops, accounting for 70.08%, respectively. And the method of inhalation exposure health risk assessment was firstly used to evaluate carcinogenicity and non-carcinogenicity risk for sprayers in ARIs. The cumulative lifetime carcinogenic risk (LCR) for 24 sampled VOCs were within acceptable ranges, while the mean hazard index (HI) for 1 year with 44 sampled VOCs was over 1. Among them, ethyl alcohol had a high carcinogenic risk in both mixed water-based paint (MP) and solvent-based paint workshops. The mean HI associated with aromatics were 2.88E - 3 and 4.30E - 3 for 1 h in MP and WPS workshops. O-ethyl toluene and acetone are VOC components that need to be paid attention to in future paint raw materials and spraying operations. Our study will provide the important references for the standard of VOC occupational exposure health limits in ARIs.

Biocontrol activity and potential mechanism of volatile organic compounds from Aspergillus niger strain La2 against pear Valsa canker.

Valsa canker caused by Valsa pyri is one of the most destructive diseases of pear, leading to severe yield and economic losses. Volatile organic compounds (VOCs) from endophytes have important roles in the regulation of plant disease. In this study, we investigated the biocontrol activity of the endophytic fungus Aspergillus niger strain La2 and its antagonistic VOCs against pear Valsa canker. Strain La2 exhibited an obvious inhibitory effect against V. pyri. A colonization assay suggested that strain La2 could complete its life cycle on pear twigs. The symptoms of pear Valsa canker were weakened on detached pear twigs after treatment with strain La2. In addition, VOCs from strain La2 also significantly suppressed mycelial growth in V. pyri. Based on the results of headspace solid-phase microextraction/gas chromatography-mass spectrometry analysis, six possible VOCs produced by strain La2 were detected, of which 2,4-di-tert-butylphenol and 4-methyl-1-pentanol were the main antagonistic VOCs in terms of their effect on pear Valsa canker in vitro and in vivo. Further results showed that 4-methyl-1-pentanol could destroy the V. pyri hyphal structure and cell membrane integrity. Importantly, the activities of pear defense-related enzymes (polyphenol oxidase, phenylalanine ammonia lyase and superoxide dismutase) were enhanced after 4-methyl-1-pentanol treatment in pear twigs, suggesting that 4-methyl-1-pentanol might induce a plant disease resistance response. Aspergillus niger strain La2 and its VOCs 2,4-di-tert-butylphenol and 4-methyl-1-pentanol have potential as novel biocontrol agents of pear Valsa canker. © 2024 Society of Chemical Industry.

Attraction of entomopathogenic nematodes to black truffle and its volatile organic compounds: A new approach for truffle beetle biocontrol

The European truffle beetle, Leiodes cinnamomeus, is the most important pest in black truffle (Tuber melanosporum) plantations. Entomopathogenic nematodes (EPNs) are a promising biological control agents against L. cinnamomeus. EPNs may employ multiple sensory cues while seeking for hosts, such as volatile organic compounds (VOCs) and CO2 gradients. We report for the first time the attraction of EPNs to truffle fruitbodies, and identified some VOCs potentially playing a key role in this interaction. We conducted olfactometer assays to investigate the attraction behavior of Steinernema feltiae and Steinernema carpocapsae towards both T. melanosporum fruitbodies and larvae of L. cinnamomeus. Subsequently, a chemotaxis assay using agar plates was performed to determine which of the 14 of the main VOCs emitted by the fruitbodies attracted S. feltiae at low (0.1 %) and high (mg/100 g truffle) concentrations. Both EPN species were attracted to mature fruitbodies of T. melanosporum, which may enhance the likelihood of encountering L. cinnamomeus during field applications. L. cinnamomeus larvae in the presence of truffles did not significantly affect the behavior of EPNs 24 h after application, underscoring the importance of the chemical compounds emitted by truffles themselves. Chemotaxis assays showed that four long-chain alcohol compounds emitted by T. melanosporum fruitbodies attracted S. feltiae, especially at low concentration, providing a first hint in the chemical ecology of a little-studied ecological system of great economical value. Further studies should be conducted to gain a finer understanding of the tritrophic interactions between T. melanosporum, EPNs, and L. cinnamomeus, as this knowledge may have practical implications for the efficacy of EPNs in the biological control of this pest.

Establishment and verification of anthropogenic speciated VOCs emission inventory of Central China

Improving the accuracy of anthropogenic volatile organic compounds (VOCs) emission inventory is crucial for reducing atmospheric pollution and formulating control policy of air pollution. In this study, an anthropogenic speciated VOCs emission inventory was established for Central China represented by Henan Province at a 3 km × 3 km spatial resolution based on the emission factor method. The 2019 VOCs emission in Henan Province was 1003.5 Gg, while industrial process source (33.7%) was the highest emission source, Zhengzhou (17.9%) was the city with highest emission and April and August were the months with the more emissions. High VOCs emission regions were concentrated in downtown areas and industrial parks. Alkanes and aromatic hydrocarbons were the main VOCs contribution groups. The species composition, source contribution and spatial distribution were verified and evaluated through tracer ratio method (TR), Positive Matrix Factorization Model (PMF) and remote sensing inversion (RSI). Results show that both the emission results by emission inventory (EI) (15.7 Gg) and by TR method (13.6 Gg) and source contribution by EI and PMF are familiar. The spatial distribution of HCHO primary emission based on RSI is basically consistent with that of HCHO emission based on EI with the R-value of 0.73. The verification results show that the VOCs emission inventory and speciated emission inventory established in this study are relatively reliable.

Volatile organic components as Covid-19 biomarkers: a systematic review

In March 2020, the WHO declared the novel Coronavirus pandemic with 118,000 cases, 4.2 thousand deaths, and 114 affected countries. Amidst the absence of effective treatments and vaccines, scientists focused on diagnosing and preventing transmission. Pathogenic agent infections induce cellular behavior changes, crucial for developing diagnostic techniques. A systematic review, following PRISMA guidelines, investigated COVID-19 and volatile organic compound (VOC) biomarkers. From 35 selected articles, two main VOC detection approaches emerged: trained dogs and chemical-analytical tools with artificial intelligence. VOC detection proved comparable to the gold standard PCR test for COVID-19 diagnosis. While not a replacement, VOC detection complements PCR testing, offering a unique health approach. Overall, the review highlights the efficacy of VOC detection, especially in areas with limited PCR access. However, these techniques should supplement other preventive measures like mask-wearing, social distancing, and hand hygiene.

The Effect of Wooden Building Materials on the Indoor Air Quality of Houses

This work focuses on researching wood as a low-emitting building material. Many studies showed that by regulating the emission of adverse chemicals from pressed wood products, they could be recycled as low-emitting materials. The presented case study, shows the measurements of the indoor air quality in a passive, low-energy, wooden, light frame house. Concentrations of Volatile Organic Compounds (VOC) and formaldehyde were measured and compared with data from other case studies made in this subject and with the current Hungarian and international regulations of adverse chemicals. The main VOC materials which concentrations were significant in all measurements were terpenes (limonene, alpha-pinene, 3-carene), aliphatic-hydrocarbons and aldehydes (acetic acid, 2-Methoxy-1-ethylmethyl acetate). The comparison showed that the concentrations of benzene, toluene, naphthalene, formaldehyde, and styrene were not deviant from the average values measured by other case studies. The observations showed that the main influencing factors of indoor air quality were the changes in indoor temperature, relative humidity, air exchange rate, and human activities. The conclusion is that the wooden materials applied in the house are low-emitting materials and do not pose a health risk for people.

Identification of bioactive compounds of Bacillus velezensis HNA3 that contribute to its dual effects as plant growth promoter and biocontrol against post-harvested fungi.

Bacillus velezensis HNA3 displayed dual bioactivities as a plant growth promoter and a biocontrol agent against five isolated post-harvest phytopathogens: Alternaria alternata, Cladosporium cladosporioides, Penicillium expansum, Monilinia fructicola, and Fusarium oxysporum. Moreover, the volatile organic compounds (VOCs) emitted by HNA3 exhibited remarkable efficacy, achieving 100% fungal inhibition against Alternaria alternata and Cladosporium cladosporioides. This is the initial study to demonstrate the HNA3-emitted VOCs effect on enhancing soybean seedling growth and seed germination by breaking seed dormancy and improving root construction. Semi-VOCs and emitted VOCs were identified by two methods of extraction coupled with gas chromatography-mass spectrometry. A total of 14 main VOCs were detected; phenol,2,4-bis(1,1-dimethylethyl) and 1,2-benzenedicarboxylic acid are the most abundant semi-VOCs, both are known to have anti-fungal and plant growth-promoting properties. 9-Octadecenoic acid (z)-, methyl ester is the most common volatile compound emitted by HNA3 followed by hexadecanoic acid, methyl ester and heptadecanoic acid, methyl ester. It is noteworthy that heptadecanoic acid, methyl ester has not been previously detected in Bacillus spp. Pure 9-octadecenoic acid (z)-, methyl ester, as well as heptadecanoic acid, methyl ester, exhibited inhibitory effects on the fungal growth of all isolated phytopathogens. Interestingly, when combined, these compounds synergistically eradicated fungal growth. Indole acetic acid and serotonin, both classified as plant growth-promoting indoles, have been identified within HNA3. Moreover, during the phytopathogen inhibition stage, HNA3 demonstrated upregulation in gene expression associated with non-VOCs, including bacillibactin, bacillomycin, bacilysin, and surfactin. This study publicized an extensive variety of bioactive compounds produced by HNA3 liable for its bioactivities.IMPORTANCEThe current study is an extension to our previous work on the plant growth-promoting rhizobacteria (PGPR) Bacillus velezensis HNA3 strain, which comes to confirm and reveals the huge stock of active secondary metabolites produced by HNA3. HNA3-emitted volatile organic compounds (VOCs) have demonstrated the capacity to impede the growth of phytopathogens affecting some fruits and vegetables, even in the absence of direct contact. Additionally, these volatiles enhanced soybean seed germination by breaking seed dormancy and inducing root system development. Furthermore, they promoted seedling growth, giving it prominence in soybean cultivation. The relevance of active volatiles derives from the fact that they can be developed as natural-safe biocontrol agents and plant promoters. This research validates the remarkable bioactivities exhibited by the Bacillus velezensis HNA3 and their potential applications in agriculture as an inoculant, encompassing biocontrol, plant growth promotion, and seed germination activities, thereby offering a safer alternative to hazardous chemicals.

Volatile organic compounds produced by Bacillus aryabhattai AYG1023 against Penicillium expansum causing blue mold on the Huangguan pear

Previous research on Bacillus aryabhattai has mainly focused on bioremediation, biosynthesis, and promotion of plant growth, whereas the function of B. aryabhattai on antifungal activity remains to be explored. In this study, we isolated a biocontrol bacterium with antagonistic activity against post-harvest pathogenic fungi by releasing volatile organic compounds (VOCs). We aimed to assess the effectiveness of VOCs produced by B. aryabhattai in prevention of the development of blue mold caused by Penicillium expansum in the Huangguan pear, and reveal the inhibitory mechanism against the pathogenic fungi. Using molecular methods, the biocontrol bacterium was identified as Bacillus aryabhattai AYG1023. 2-Nonanol was identified as the main VOC by solid-phase microextraction gas chromatography-mass spectrometry (SPME-GC/MS). It showed strong inhibition of mycelial growth and conidial germination when treated at the minimum inhibitory concentration (MIC). Scanning and transmission electron microscopy showed that 2-nonanol caused abnormal changes in mycelial and conidial ultrastructure. 2-Nonanol also damaged the integrity of fungal cell membranes and reduced the ergosterol content to 44.77% of P. expansum. In addition, the production of secondary metabolites in P. expansum including patulin and citrinin was significantly reduced by 2-nonanol. Transcriptome analysis revealed that 2-nonanol modulated the expression of genes involved in development, and conidiation pathways, as well as secondary metabolite biosynthesis including steroid biosynthesis, citrinin production and patulin production. Furthermore, blue mold was completely inhibited by treatment with 0.04 μL mL−1 2-nonanol for 48 h on the Huangguan pear. In conclusion, Bacillus aryabhattai AYG1023 was identified as a promising and efficient agent for controlling post-harvest diseases via the release of VOCs, and the outcome of this study lays a theoretical foundation for future applications.

Emission characteristics, environmental impact, and health risk assessment of volatile organic compounds (VOCs) during manicure processes

In recent years, the nail industry has been widely popular in China, and the use of nail care products has also significantly increased. Due to its high content of volatile solvents, the released VOCs not only have a negative impact on indoor air quality but also pose a health threat to nail salon workers who are highly exposed to such environments. The objectives of this research were to characterize VOCs emissions from detailed manicure processes and to evaluate the impact on the environment and health risks. Results showed that the VOCs concentration in the anti-warping treatment process was much higher than that in other manicure steps, at 360.69 mg/m3, making its contributions of OFP and SOA equally prominent. The trend of concentration contribution was similar to that of OFP, and OVOCs were the most significant contributor to the VOCs components in the whole manicure process. Since organic solvent nail gels were also frequently used in most steps, the main VOCs were methanol, ethanol and ethyl acetate. Aromatics were the component that contributed the most to SOA, and its contributions in all processes were >85 %. Health risk assessments performed in our study indicated that acrolein was the main non-carcinogen, and the carcinogenic risk of this study could be ignored. The results of this study can be used as a basis for controlling VOCs emission and reducing exposure to VOCs in nail salons.

Volatile Organic Compounds of Scheffersomyces spartinae W9 Have Antifungal Effect against Botrytis cinerea on Strawberry Fruit.

This study aims to evaluate the antifungal effects of volatile organic compounds (VOCs) produced by a marine biocontrol yeast, Scheffersomyces spartinae W9. The results showed that the VOCs from the yeast inhibited the growth of Botrytis cinerea mycelium and spore germination by 77.8% and 58.3%, respectively. Additionally, it reduced the disease incidence and lesion diameter of gray mold on the strawberry fruit surface by 20.7% and 67.4%, respectively. Electronic micrographs showed that VOCs caused damage to the morphology and ultrastructure of the hyphae. Based on headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME/GC-MS), S. spartinae W9 emitted 18 main VOCs, and the pure substance of VOCs, such as 3-methyl-1-butanol, 2-methyl-1-butanol, 2-phenylethanol, and isoamyl acetate, showed antifungal effects against B. cinerea mycelium growth. Among them, 2-phenylethanol exhibited the strongest antifungal activity. It has been concluded that VOCs are the key antifungal mechanism of S. spartinae W9, and a promising strategy for controlling gray mold on strawberry fruit.

Feasibility of using volatile urine fingerprints for the differentiation of sexually transmitted infections

Sexually transmitted infections (STIs) are a public health problem worldwide, and current diagnostic methods have certain limitations. In recent years, volatile organic compounds (VOCs) have been studied as an alternative diagnostic method. Due to this, this study aimed to detect, in vaginal swabs and urine samples, VOCs emitted by highly prevalent STIs-causing bacteria (Chlamydia trachomatis, Mycoplasma genitalium, and Neisseria gonorrhoeae) to identify potential biomarkers that allow the detection of these STIs. VOCs detected in urine samples showed a better differentiation of patients with STIs due to C. trachomatis from those not infected, with 2,6-dimethyl-4-heptanone as the volatile compound most related to the presence of this bacterium. Among the VOCs most related to M. genitalium in urine, 4-methyltetradecane and 2-methylpentadecane stood out, while 3,4,4-trimethyl-2-cyclohexen-1-one was the VOC most closely related to N. gonorrhoeae infection. Moreover, C12 alcohols were the main VOC family associated with positive samples in all three bacteria, which could indicate the presence of aldehyde reductases in their metabolism. In contrast, alcohols such as 3-methyl-1-heptanol and 1-octanol, as well as dimethyl esters, were more associated with negative samples and may be useful in ruling out an STI caused by one of these three bacteria. In short, the VOCs identified as potential biomarkers in patients with infection by C. trachomatis, M. genitalium, or N. gonorrhoeae could be used in the early diagnosis of these STIs, quickly interrupting the chain of transmission, especially interesting in asymptomatic patients.Key points• Sexually transmitted infections are a serious public health problem worldwide.• The study of VOCs in multiple infections is increasing in recent years.• The identification of volatile biomarkers could allow new diagnostic methods.Graphical abstract

Cultivar differences in the hormonal crosstalk regulating apple fruit development and ripening: Relationship with flavour components and postharvest susceptibility to Penicillium expansum

The hormonal interplay during the on-tree development and ripening of three apple cultivars with known differences in their postharvest ripening patterns was studied, at the biochemical and targeted gene expression level, along with characterizing the changes in main sugars, acids, phenylpropanoids and volatile organic compounds (VOCs). Our findings suggest that in ‘Royal Gala’ and ‘Opal®’ apples, a peak in indole 3-acetic acid (IAA) seems necessary to activate ethylene metabolism, being its intensity proportional to the ethylene production. The interplay between IAA and ethylene appears to be mediated by MdARF5, responsible for activating the expression of MdACS3 and triggering ethylene metabolism. On the other hand, the lack of ethylene production observed in ‘Granny Smith’ apples was likely related to the absence of an IAA peak and possibly caused by the over activation of IAA conjugation mechanisms leading to a greater accumulation of IAA inactive conjugates such as indole-3-acetyl-aspartate (IAAsp). Abscisic acid (ABA) accumulation was only observed in cultivars with the ability to accumulate sucrose and produce ethylene, suggesting a possible crosstalk among those hormones and sucrose in orchestrating apple on-tree ripening. While differences in hormone levels among cultivars led to noticeable differences in some specific VOCs, no evident associations were found between hormone changes and the accumulation or degradation of monosaccharides, organic acids or phenolic compounds during fruit development and ripening. Likewise, no clear relationship was found between the fruit susceptibility to blue mould and hormonal levels yet certain specific biochemical compounds (i.e., procyanidins and sucrose) could be acting as a source of resistance or susceptibility, respectively, to blue mould development. Overall, understanding the cultivar specific hormonal regulation of apple on-tree ripening provides valuable insights to optimize fruit quality at the time of harvest as well as to develop strategies for improved postharvest management.

Emission factors and source profiles of VOCs emitted from coke production in Shanxi, China

Coking plants in China generate a substantial amount of volatile organic compounds (VOCs). The emission factors (EFs) of VOCs from coking plants are not well known, and thus, this study characterized the VOCs in the emissions from four coking plants in Shanxi, China. The EFs of VOCs from different stages of the coking process were calculated, and coal charging exhibited the highest EFs of VOCs, followed by the flue gases from combustion of coke oven gas, wastewater treatment, coke pushing and chemical byproduct recycling. The VOCs in emissions differed by coking process. Alkanes, aromatics and alkenes were the main VOCs emitted during the coking, wastewater treatment and chemical byproduct recycling processes, respectively. To effectively control the contribution of VOCs from coking processes to secondary organic aerosols and ozone formation, attention should be given to wastewater treatment and coal loading processes. The mean annual weight of VOCs emitted from coking plants in China from 2019 to 2021 was estimated to be 32.91 Gg with coking, chemical byproduct recycling, and wastewater treatment processes accounting for 91.34%, 7.85%, and 0.80% of total VOCs, respectively. An uneven spatial distribution of VOCs emissions in China was identified, with Shanxi, Shaanxi, Hebei, Inner Mongolia and Shandong being the largest contributors.