Stability of selected exhaled breath volatiles stored in Tenax®TA adsorbent tubes at -80 °C.

Preservation of the breath sample integrity during storage and transport is one of the biggest challenges in off-line exhaled breath gas analysis. In this context, adsorbent tubes are frequently used as storage containers for use with analytical methods employing gas chromatography with mass spectrometric detection. The key objective of this short communication is to provide data on the recovery of selected breath volatiles from Tenax®TA adsorbent tubes that were stored at -80 °C for up to 90 d. For this purpose, an Owlstone Medical's ReCIVA®Breath Sampler was used for exhaled breath collection. The following fifteen compounds, selected to cover a range of chemical properties, were monitored for their stability: isoprene, n-heptane, n-nonane, toluene, p-cymene, allyl methyl sulfide, 1-(methylthio)-propane, 1-(methylthio)-1-propene,α-pinene, DL-limonene,ß-pinene,γ-terpinene, 2-pentanone, acetoin and 2,3 butanedione. All compounds, but one (acetoin), were found to be stable during the first 4 weeks of storage (recovery within ± 2 × RSD). Furthermore, n-nonane was stable during the whole of the investigated period.

The sky is not the limit: Successful foliar application of Steinernema spp. entomopathogenic nematodes to control Lepidopteran caterpillars.

Entomopathogenic nematodes (EPNs) are ubiquitous soil-thriving organisms that use chemical cues to seek and infect soil-dwelling arthropods, yielding various levels of biological control. Going beyond soil application, scientists and practitioners started exploring the option of applying EPNs onto the foliage of crops in attempts to manage leaf-dwelling insect pests as well. Despite some success, particularly with protective formulations, it remains uncertain whether EPNs could indeed survive the phyllospheric environment, and successfully control foliar insect pests. In this context, we tested the potential of commercially produced Steinernema feltiae and S. carpocapsae, two of the most commonly used EPNs in the field of biological control, in controlling Lepidopteran foliar pests of economic importance, i.e. Tuta absoluta and Spodoptera spp. caterpillars as models. We first tested the survival and efficacy of both EPN species against the Lepidopteran caterpillars when applied onto tomato, sweet pepper and lettuce leaves, under controlled conditions and in commercial greenhouse conditions, respectively. Subsequently, we explored the behavioural responses of the EPNs to environmental cues typically encountered in the phyllosphere, and analysed plant volatile organic compounds (VOCs). Our results show that both S. feltiae and S. carpocapsae successfully survived and infected the foliar caterpillars, reaching similar level of control to a standard chemical pesticide in commercial practices. Remarkably, both EPN species survived and remained effective up to four days in the phyllosphere, and needed only a few hours to successfully penetrate the caterpillars. Interestingly, S. feltiae was attracted to VOCs from tomato plants, and tended to prefer those from caterpillar-induced plants, suggesting that the nematodes may actively forage toward its host, although it has never been exposed to leaf-borne volatiles during its evolution. The present study shows the high potential of steinernematids in managing major foliar pests in greenhouses and in becoming a key player in foliar biological control. In particular, the discovery that EPNs use foliar VOCs to locate caterpillar hosts opens up new opportunities in terms of application techniques and affordable effective doses.

Exhaled volatile organic compounds in the detection of colorectal cancer: a systematic review and meta-analysis.

There is an apparent need for novel non-invasive colorectal cancer (CRC) screening tests that are more acceptable to patients and can reliably detect CRC or reduce the number of unnecessary colonoscopies performed in cancer-free patients. An emerging number of studies demonstrate the potential value of exhaled volatile organic compounds (VOCs) as a diagnostic and triaging test for CRC. A systematic appraisal and meta-analysis of the published evidence was done to determine whether exhaled VOCs can be used in the detection and screening of CRC. Nine electronic databases were searched from inception of the databases until August 2020. Quantitative and descriptive data of CRC patients and healthy control (HC) participants who underwent VOCs breath analysis was extracted. In addition, where possible, sampling methods, analytical platforms, processors, and specific breath biomarkers found in each study were recorded. Fourteen articles were included in the systematic review with 491 colorectal patients and 754 HC participants (n=1245). Sub-group meta-analysis was conducted on nine of those articles and the pooled sensitivity was estimated to be 0.89 (95 % CI = 0.80-0.99) whereas specificity was 0.83 (95 % CI = 0.74-0.92). Heterogeneity of pooled sensitivity and specificity was estimated as I2=11.11 %. Although this study was limited by small sample size and different analytical platforms, the proposed future framework resolves such limitations and standardizes future research. It is reasonable to deduce that VOCs breath analysis is certainly a field of research that can progress to replace traditional methods within the framework of CRC screening and diagnosis.

Volatile metabolomics and transcriptomics analyses provide insights into the mechanism of volatile changes during fruit development of 'Ehime 38' (Citrus reticulata) and its bud mutant.

Volatile compounds are important determinants affecting fruit flavor. Previous study has identified a bud mutant of 'Ehime 38' (Citrus reticulata) with different volatile profile. However, the volatile changes between WT and MT during fruit development and underlying mechanism remain elusive. In this study, a total of 35 volatile compounds were identified in the pulps of WT and MT at five developmental stages. Both varieties accumulated similar and the highest levels of volatiles at stage S1, and showed a downward trend as the fruit develops. However, the total volatile contents in the pulps of MT were 1.4-2.5 folds higher than those in WT at stages S2-S5, which was mainly due to the increase in the content of d-limonene. Transcriptomic and RT-qPCR analysis revealed that most genes in MEP pathway were positively correlated with the volatile contents, of which DXS1 might mainly contribute to the elevated volatiles accumulation in MT by increasing the flux into the MEP pathway. Moreover, temporal expression analysis indicated that these MEP pathway genes functioned at different developmental stages. This study provided comprehensive volatile metabolomics and transcriptomics characterizations of a citrus mutant during fruit development, which is valuable for fruit flavor improvement in citrus.

Progress and challenges of developing volatile metabolites from exhaled breath as a biomarker platform.

BACKGROUND: The multitude of metabolites generated by physiological processes in the body can serve as valuable biomarkers for many clinical purposes. They can provide a window into relevant metabolic pathways for health and disease, as well as be candidate therapeutic targets. A subset of these metabolites generated in the human body are volatile, known as volatile organic compounds (VOCs), which can be detected in exhaled breath. These can diffuse from their point of origin throughout the body into the bloodstream and exchange into the air in the lungs. For this reason, breath VOC analysis has become a focus of biomedical research hoping to translate new useful biomarkers by taking advantage of the non-invasive nature of breath sampling, as well as the rapid rate of collection over short periods of time that can occur. Despite the promise of breath analysis as an additional platform for metabolomic analysis, no VOC breath biomarkers have successfully been implemented into a clinical setting as of the time of this review. AIM OF REVIEW: This review aims to summarize the progress made to address the major methodological challenges, including standardization, that have historically limited the translation of breath VOC biomarkers into the clinic. We highlight what steps can be taken to improve these issues within new and ongoing breath research to promote the successful development of the VOCs in breath as a robust source of candidate biomarkers. We also highlight key recent papers across select fields, critically reviewing the progress made in the past few years to advance breath research. KEY SCIENTIFIC CONCEPTS OF REVIEW: VOCs are a set of metabolites that can be sampled in exhaled breath to act as advantageous biomarkers in a variety of clinical contexts.

Combination of real-time and hyphenated mass spectrometry for improved characterisation of exhaled breath biomarkers in clinical research.

Exhaled breath volatilomics is a powerful non-invasive tool for biomarker discovery in medical applications, but compound annotation is essential for pathophysiological insights and technology transfer. This study was aimed at investigating the interest of a hybrid approach combining real-time proton transfer reaction-time-of-flight mass spectrometry (PTR-TOF-MS) with comprehensive thermal desorption-two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (TD-GCxGC-TOF-MS) to enhance the analysis and characterization of VOCs in clinical research, using COVID-19 as a use case. VOC biomarker candidates were selected from clinical research using PTR-TOF-MS fingerprinting in patients with COVID-19 and matched to the Human Breathomic Database. Corresponding analytical standards were analysed using both a liquid calibration unit coupled to PTR-TOF-MS and TD-GCxGC-TOF-MS, together with confirmation on new clinical samples with TD-GCxGC-TOF-MS. From 26 potential VOC biomarkers, 23 were successfully detected with PTR-TOF-MS. All VOCs were successfully detected using TD-GCxGC-TOF-MS, providing effective separation of highly chemically related compounds, including isomers, and enabling high-confidence annotation based on two-dimensional chromatographic separation and mass spectra. Four VOCs were identified with a level 1 annotation in the clinical samples. For future applications, the combination of real-time PTR-TOF-MS and comprehensive TD-GCxGC-TOF-MS, at least on a subset of samples from a whole study, would enhance the performance of VOC annotation, offering potential advancements in biomarker discovery for clinical research.

Aqueous VOCs in complex water environment of oil exploitation sites: Spatial distribution, migration flux, and risk assessment.

Pollution of the aqueous environment by volatile organic compounds (VOCs) has caused increasing concerns. However, the occurrence and risks of aqueous VOCs in oil exploitation areas remain unclear. Herein, spatial distribution, migration flux, and environmental risks of VOCs in complex surface waters (including River, Estuary, Offshore and Aquaculture areas) were investigated at a typical coastal oil exploitation site. Among these surface waters, River was the most polluted area, and 1,2-Dichloropropane-which emerges from oil extraction activities-was the most prevalent VOC. Positive matrix factorization showed that VOCs pollution sources changed from oil exploitation to offshore disinfection activities along River, Estuary, Offshore and Aquaculture areas. Annual volatilization of VOCs to the atmosphere was predicted to be ∼34.42 tons, and rivers discharge ∼23.70 tons VOCs into the Bohai Sea annually. Ecological risk assessment indicated that Ethylbenzene and Bromochloromethane posed potential ecological risks to the aquatic environment, while olfactory assessment indicated that VOCs in surface waters did not pose an odor exposure risk. This study provides the first assessment of the pollution characteristics of aqueous VOCs in complex aqueous environments of oil exploitation sites, highlighting that oil exploitation activities can have nonnegligible impacts on VOCs pollution profiles.

Defense of Cabbages against Herbivore Cutworm Spodoptera litura under Cd Stress and Insect Herbivory Stress simultaneously.

Biotic (e.g., heavy metal) and abiotic stress (e.g., insect attack) can affect plant chemical defense, but little is known about the changes in plant defense when they occur concurrently. Herein, the impacts of heavy metal cadmium (Cd) stress and insect herbivory stress on the direct and indirect defense of two cultivar cabbages of Brassica campestris, the low-Cd cultivar Lvbao701 and the high-Cd cultivar Chicaixin No.4, against the herbivore cutworm Spodoptera litura were investigated. Although 10 mg kg-1 Cd stress alone inhibited leaf secondary metabolites (total phenolics, flavonoids), it also reduced the feeding rate and odor selection of S. litura towards both cultivar cabbages, especially for Lvbao701, by increasing leaf Cd content and repellent volatile organic compounds (VOCs) (6-methyl-5-hepten-2-one, 7,9-di-tert-butyl-1-oxaspiro(4,5)deca-6,9-diene-2,8-dione), and reducing soluble sugar and attractive VOCs (3-methyl-3-pentanol, 2,5-hexanedione, tetradecanal). Under 2.5 mg kg-1 Cd and herbivory stress, although leaf total phenolics and flavonoids increased significantly, the feeding rate and odor selection of S. litura towards both cultivar cabbages increased, especially for Chicaixin No.4, indicating that the chemical defense of cabbages was depressed. Therefore, Cd stress alone improved the insect resistance of cabbages, whereas herbivory stress weakened the enhanced cabbages defence by Cd stress. The low-Cd cultivar Lvbao701 presented stronger insect resistance than Chicaixin No.4, suggesting that Lvbao701 application in Cd-polluted soil can not only decrease Cd transmission to higher levels in the food chain but also reduce pest occurrence.

The essential oil chemical composition of a rare ethnopharmacoligical plant: Verbascum creticum (L.) Cav.

The genus Verbascum L, belonging to the Scrophulariaceae family, is native to Europe, Africa and Asia. The use of plants of this genus in the popular medicine has been largely reported. In the present study the chemical composition of the essential oil from aerial parts of Verbascum creticum (L.) Cav., a rare plant, never previously investigated, known for its anti-inflammatory properties of the intestinal mucosa and in the treatment of acute and chronic catarrhs, growing in Algeria, Baleares, Calabria, Sardinia, Sicily, Spain and Tunisia, was evaluated by GC-MS. The main components of its essential oil (Vc) were 1-octen-3-ol (23.9%), cis-3-hexen-1-ol (9.4%), phenylethanal (4.6%), and 2-methyl-benzofurane (4.6%). The comparison with all the other studied essential oils of genus Verbascum is discussed. Furthermore, a review of the use of the Verbascum species in the popular medicine has been carried out.

Effects of discharge plasma on seed germination and volatile compounds content of Agropyron Mongolicum.

To investigate the effects of discharge plasma on Agropyron mongolicum seeds, various treatments including direct exposure to discharge plasma, combined treatment with discharge plasma and plasma-activated water (PAW) were applied to the seeds. The changes in germination rate, MDA content, and volatile compound levels of Agropyron mongolicum seeds after different treatments were examined. The results showed that the direct effect of plasma had no significant effect on the MDA content or germination rate of Agropyron mongolicum seeds due to the limited penetration depth. However, the combined effect of plasma and activated water could cause active nitrogen and oxygen particles to enter the seeds and cause oxidative stress damage. After 18 h of combined treatment, the MDA content increased significantly, and the germination rate decreased to below the semilethal dose, which was 33.44 %. After plasma treatment, 55 volatile compounds, mainly alcohols, aldehydes and ketones, were identified from the seeds of Agropyron mongolicum. Due to the oxidation and modification of the plasma, the content of most aldehydes increased with increasing reaction time. After screening, 13 volatile organic compounds could be used as potential markers to distinguish between different treatment methods. These results reveal the mechanism underlying the biological effects of plasma treatment on Agropyron mongolicum seeds.

Corrigendum: Effects of Caragana korshinskii tannin on fermentation, methane emission, community of methanogens, and metabolome of rumen in sheep.

[This corrects the article DOI: 10.3389/fmicb.2024.1334045.].

Climate impacts of landfill gas emissions: Analysis for 20-year and 100-year time horizons.

Climate impacts of landfill gas emissions were investigated for 20- and 100-year time horizons to identify the effects of atmospheric lifetimes of short- and long-lived drivers. Direct and indirect climate impacts were determined for methane and 79 trace species. The impacts were quantified using global warming potential, GWP (direct and indirect); atmospheric degradation (direct); tropospheric ozone forming potential (indirect); secondary aerosol forming potential (indirect) and stratospheric ozone depleting potential (indirect). Effects of cover characteristics, landfill operational conditions, and season on emissions were assessed. Analysis was conducted at five operating municipal solid waste landfills in California, which collectively contained 13% of the waste in place in the state. Climate impacts were determined to be primarily due to direct emissions (99.5 to 115%) with indirect emissions contributing -15 to 0.5%. Methane emissions were 35 to 99% of the total emissions and the remainder mainly greenhouse gases (hydro)chlorofluorocarbons (up to 42% of total emissions) and nitrous oxide. Cover types affected emissions, where the highest emissions were generally from intermediate covers with the largest relative landfill surface areas. Landfill-specific direct emissions varied between 683 and 103,411 and between 381 and 37,925 Mg CO2-eq./yr for 20- and 100-yr time horizons, respectively. Total emissions (direct + indirect) were 680 to 103,600 (20-yr) and were 374 to 38,108 (100-yr) Mg CO2-eq./yr. Analysis time horizon significantly affected emissions. The 20-yr direct and total emissions were consistently higher than the 100-yr emissions by up to 2.5 times. Detailed analysis of time-dependent climate effects can inform strategies to mitigate climate change impacts of landfill gas emissions.

Ectoine maintains the flavor and nutritional quality of broccoli during postharvest storage.

The bacterial derived osmolyte ectoine has been shown to stabilize cell structure and function, a property that may help to extend the shelf life of broccoli. The impact of ectoine on broccoli stored for 4 d at 20 °C and 90% relative humidity was investigated. Results indicated that 0.20% ectoine treatment maintained the quality of broccoli, by reducing rate of respiration and ethylene generation, while increasing the levels of total phenolics, flavonoids, TSS, soluble protein, and vitamin C, relative to control. Headspace-gas chromatography-mass spectrometry, transcriptomic and metabolomic analyses revealed that ectoine stabilized aroma components in broccoli by maintaining level of volatile compounds and altered the expression of genes and metabolites associated with sulfur metabolism, as well as fatty acid and amino acid biosynthesis pathways. These findings provide a greater insight into how ectoine preserves the flavor and nutritional quality of broccoli, thus, extending its shelf life.

Revealing the mechanism of flavor improvement of fermented goat milk based on lipid changes.

The mechanism of goat milk (GM) flavor improvement based on lipid changes requires understanding. According to sensory evaluation results, the texture, taste, appearance, aroma, and overall acceptability score of Guishan fermented goat milk (GMF) were higher than those of GM. In total, 779 lipid molecules and 121 volatile compounds were formed from the metabolite-lipid level in the GM and GMF, as determined through lipidomics and gas chromatography-mass spectrometry. The key volatile flavor compounds in the GMF were (E,E)-2,4-decadienal, ethyl acetate, acetoin, 2,3-pentanedione, acetic acid, and 2,3-butanedione. Of them, 60 lipids significantly contributed to the flavor profiles of the GMF, based on the correlation analysis. The triacylglycerides (TAGs) 12:0_14:0_16:0 and 13:0_13:0_18:2 contributed to aroma retention, while TAG and phosphatidylethanolamine were identified as key substrates for flavor compound formation during fermentation. Lipids associated with glycerophospholipid and linoleic acid metabolism pathways significantly affected volatile compound formation in the GMF. This study provides an in-depth understanding of the lipids and flavors of the GMF, and this information will be useful for the development of specific GMF products.

Comprehensive characterization of the differences in metabolites, lipids, and volatile flavor compounds between Ningxiang and Berkshire pigs using multi-omics techniques.

This study was conducted to comprehensively characterize, metabolites, lipids, and volatile flavor compounds of NingXiang (NX) pigs, Berkshire (BKS) pigs, and their crossbred (Berkshire × Ningxiang, BN) pigs using multi-omics technique. The results showed that NX had high intramuscular fat (IMF) content and meat redness. The metabolite and lipid compositions were varied greatly among three pig breeds. The NX pigs exhibited distinctive sweet, fruity, and floral aroma while BN pigs have inherited this flavor profile. 2-pentylfuran, pentanal, 2-(E)-octenal, and acetic acid were the key volatile flavor compounds (VOC) of NX and BKS pork. The VOCs were influenced by the composition and content of metabolites and lipids. The NX pigs have excellent meat quality traits, unique flavor profiles, and high degree of genetic stability regarding flavor. The study deepens our understanding of the flavor of Chinese indigenous pigs, providing theoretical basis to understand the meat flavor regulation under different feeding conditions.

Evaluation of nutritional, technological, oxidative, and sensory properties of low-sodium and phosphate-free mortadellas produced with bamboo fiber, pea protein, and mushroom powder.

This study examined the effects of replacing alkaline phosphate (AP) with bamboo fiber (BF), isolated pea protein (PP), and mushroom powder (MP) on the nutritional, technological, oxidative, and sensory characteristics of low-sodium mortadellas. Results indicated that this reformulation maintained the nutritional quality of the products. Natural substitutes were more effective than AP in reducing water and fat exudation. This led to decreased texture profile analysis (TPA) values such as hardness, cohesiveness, gumminess, and chewiness. The reformulation reduced the L* values and increased the b* values, leading to color modifications rated from noticeable to appreciable according to the National Bureau of Standards (NBS) index. Despite minor changes in oxidative stability indicated by increased values in TBARS (from 0.19 to 0.33 mg MDA/kg), carbonyls (from 2.1 to 4.4 nmol carbonyl/mg protein), and the volatile compound profile, the sensory profile revealed a beneficial increase in salty taste, especially due to the inclusion of MP, which was enhanced by the synergy with BF and PP. In summary, the results confirmed the potential of natural alternatives to replace chemical additives in meat products. Incorporating natural antioxidants into future formulations could address the minor oxidation issues observed and enhance the applicability of this reformulation strategy.

Tear Fluid as a Matrix for Biomonitoring Environmental and Chemical Exposures.

PURPOSE: Exposures to hazardous chemicals have been linked to many detrimental health effects and it is therefore critical to have effective biomonitoring methods to better evaluate key environmental exposures that increase the risk of chronic disease and death. Traditional biomonitoring utilizing blood and urine is limited due to the specialized skills and invasiveness of collecting these fluid samples. This systematic review focuses on tear fluid, which is largely under-researched, as a promising complementary matrix to the traditional fluids used for biomonitoring. The objective is to evaluate the practicability of using human tear fluid for biomonitoring environmental exposures, highlighting potential pitfalls and opportunities. RECENT FINDING: Tear fluid biomonitoring represents a promising method for assessing exposures because it can be collected with minimal invasiveness and tears contain exposure markers from both the external and internal environments. Tear fluid uniquely interfaces with the external environment at the air-tear interface, providing a surface for airborne chemicals to diffuse into the ocular environment and interact with biomolecules. Tear fluid also contains molecules from the internal environment that have travelled from the blood to tears by crossing the blood-tear barrier. This review demonstrates that tear fluid can be used to identify hazardous chemicals from the external environment and differentiate exposure groups.

GC/MS evaluation of the composition of the Aloe vera gel and extract.

This study aimed to investigate the potential use of Aloe vera (AV) as a food additive given its critical importance in food safety and health. Specifically, the natural antimicrobial and antioxidant properties of AV were examined to prevent food spoilage and extend its shelf life. This study was conducted using commercially available aloe vera gel (AVG) and aloe vera extract (AVE). These samples were tested using gas chromatography-mass spectrometry (GC-MS). The analysis involves identifying and quantifying the components using natural helium gas. The antimicrobial and antifungal effects of these components were evaluated and compared with those reported in the literature. GC-MS analysis revealed that the Aloe vera gel and extract contained various volatile components, including phenolic compounds, anthraquinone glycosides, and different esters. According to GC-MS results of the two different forms of AV, the main volatile compounds of the gel form were levoglucosan, tridecanoic acid, decanoic acid methyl ester, octadecanoic acid methyl ester, octadecanoic acid, nonadeca-1.18-diyn-4.16-diol and squalene, whereas the extract form contained volatile compounds with antifungal activity such as tridecanoic acid, octadecanoic acid methyl ester, octadecanoic acid, nonanoic acid and eicosyl acetate. Both samples exhibited antimicrobial and antifungal activities, especially against pathogens such as Staphylococcus aureus, Candida albicans, Aspergillus niger, and Escherichia coli. This study demonstrated the potential of Aloe vera gel and extract as a natural preservative for use in food because of its constituent components. This study highlights the potential use of Aloe vera as a natural additive in the food industry. Due to its antimicrobial and antifungal properties, Aloe vera offers an organic alternative to chemical additives. Aloe vera is effective at preventing food spoilage and extending shelf life, making it a suitable option for meeting consumer demand for organic and natural products.

A reduction in dietary crude protein with amino acid balance has no negative effects in pigs.

The aim of this experiment was to evaluate the effects of low crude protein (CP) level with essential amino acids (AA) addition on growth performance, nutrient digestibility, microbiota, and volatile fatty acid composition in growing pigs. A total of 160 growing pigs (Landrace × Yorkshire × Duroc [LYD]; average initial body weight 16.68 ± 0.12 kg) were randomly allotted to one of the four treatments on the basis of initial body weight. A randomized complete block design was used to conduct this experiment in the Research Center of Animal Life Sciences at Kangwon National University. There were ten pigs/replicate with four replicates in each treatment. The treatments include; CON (Control, 17.2% dietary CP level), low protein (LP)-1.10 (15.7% dietary CP level + 1.10% lysine level), LP-1.15 (15.7% dietary CP level + 1.15% lysine level), LP1.2 (15.7% dietary CP level + 1.20% lysine level). The pigs fed CON and LP-1.2 diet showed greater final body weight than that of LP-1.1 diet (p < 0.05). Although average daily gain, average daily feed intake, and feed efficiency did not show any difference in phase 2 and 3, average daily gain and feed efficiency was significantly greater in CON and LP-1.20 in phase 1. However, the average daily feed intake did not show any difference during the experimental period. Isobutyric acid and isovaleric acid composition of LP treatments were lower than CON treatment in phase 2. Total branched chain fatty acid composition was significantly lower in LP treatment in phases 1 and 2. However, there was no significant difference among treatments in phase 3. The results of this study underscore the importance of AA supplementation when implementing a low-protein diet during the early growth phase (16-50 kg) in pigs.

Electrochemical biofilter enhances performance of volatile organic compounds abatement.

An electrochemical biofilter (EBF) was developed for enhancing the removal of volatile organic compounds (VOCs) through current. The removal efficiency (RE) of toluene exhibited a notable increase of 15% while the biomass growth rate exhibited a corresponding decline of 46% under an optimal current intensity of 50 mA. Meanwhile, the efficacy of the EBF system was markedly enhanced upon the removal of n-hexane, styrene, dichloromethane, and diisobutylene. The results indicated that there was an 11% to 49% increase in RE and a 0% to 64% reduction in biomass growth rates under the influence of the current. The current stimulation inhibited the accumulation of microorganisms, thereby alleviating biofilm clogging. The relative abundance of gram-positive phyla, including Firmicutes and Actinobacteria, increased by 15% and 23%, respectively, while the traditionally dominant genera within the Proteobacteria phylum, such as Rhodococcus and Dokdonella, exhibited a decline. In addition, the presence of hydrogen peroxide, free chlorine, and superoxides in the leachate indicated that the oxidative reaction increased in EBF system. This study provides an attractive pathway for current stimulation to enhance degradation of VOCs and alleviate biofilm clogging.