Scaling up polarized RPE cell supernatant production on parylene membrane.

Age-related macular degeneration (AMD), a leading cause of vision loss, primarily arises from the degeneration of retinal pigment epithelium (RPE) and photoreceptors. Current therapeutic options for dry AMD are limited. Encouragingly, cultured RPE cells on parylene-based biomimetic Bruch's membrane demonstrate characteristics akin to the native RPE layer. In this study, we cultivated human embryonic stem cell-derived polarized RPE (hESC-PRPE) cells on parylene membranes at both small- and large-scale settings, collecting conditioned supernatant, denoted as PRPE-SF. We conducted a comprehensive analysis of the morphology of the cultured hESC-RPE cells and the secreted growth factors in PRPE-SF. To evaluate the in vivo efficacy of these products, the product was administered via intravitreal injections of PRPE-SF in immunodeficient Royal College of Surgeons (iRCS) rats, a model for retinal degeneration. Our study not only demonstrated the scalability of PRPE-SF production while maintaining RPE cell phenotype but also showed consistent protein concentrations between small- and large-scale batches. We consistently identified 10 key factors in PRPE-SF, including BMP-7, IGFBP-2, IGFBP-3, IGFBP-4, IGFBP-6, MANF, PEDF, PDGF-AA, TGFß1, and VEGF. Following intravitreal administration of PRPE-SF, we observed a significant increase in the thickness of the outer nuclear layer (ONL) and photoreceptor preservation in iRCS rats. Furthermore, correlation analysis revealed that IGFBP-3, IGFBP-4, MANF, PEDF, and TGFß1 displayed positive associations with in vivo bioactivity, while GDF-15 exhibited a negative correlation. Overall, this study highlights the feasibility of scaling up PRPE-SF production on parylene membranes without compromising its essential constituents. The outcomes of PRPE-SF administration in an animal model of retinal degeneration present substantial potential for photoreceptor preservation. Moreover, the identification of candidate surrogate potency markers, showing strong positive associations with in vivo bioactivity, lays a solid foundation for the development of a promising therapeutic intervention for retinal degenerative diseases.

Acidovorax benzenivorans sp. nov., a novel aromatic hydrocarbon-degrading bacterium isolated from a xylene-degrading enrichment culture.

A Gram-stain-negative strain, designated as D2M1T was isolated from xylene-degrading enrichment culture and characterized using a polyphasic approach to determine its taxonomic position. The 16S rRNA gene sequence analysis revealed that strain D2M1T belongs to the genus Acidovorax, with the highest 16S rRNA gene similarity to Acidovorax delafieldii DSM 64T (99.93 %), followed by Acidovorax radicis DSM 23535T (98.77 %) and Acidovorax kalamii MTCC 12652T (98.76 %). The draft genome sequence of strain D2M1T is 5.49 Mb long, and the G+C content of the genome is 64.2 mol%. Orthologous average nucleotide identity and digital DNA-DNA hybridization relatedness values between strain D2M1T and its closest relatives were below the threshold values for species demarcation confirming that strain D2M1T is distinctly separated from its closest relatives. The whole genome analysis of the strain revealed a phenol degradation gene cluster, encoding a multicomponent phenol hydroxylase (mPH) together with a complete meta-cleavage pathway including an I.2.C-type catechol 2,3-dioxygenase (C23O) gene. The strain was able to degrade benzene and ethylbenzene as sole sources of carbon and energy under aerobic and microaerobic conditions. Cells were facultatively aerobic rods and motile with a single polar flagellum. The predominant fatty acids (>10 % of the total) of strain D2M1T were summed feature 3 (C16 : 1 ω7c/C16 : 1 ω6c), C16 : 0 and summed feature 8 (C18 : 1 ω7c/C18 : 1 ω6c). The major ubiquinone of strain D2M1T was Q8, while the major polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. Based on polyphasic data, it is concluded that strain D2M1T represents a novel species of the genus Acidovorax, for which the name of Acidovorax benzenivorans sp. nov. is proposed. The type strain of the species is strain D2M1T (=DSM 115238T=NCAIM B.02679T).

Nationwide multicenter study on adverse events associated with a patency capsule: Additional survey of appropriate use of patency capsule study.

BACKGROUND AND AIM: The PillCam patency capsule (PC) without a radio frequency identification tag was released to preclude retention of the small bowel capsule endoscope (CE) in Japan in 2012. We conducted a multicenter study to determine tag-less PC-related adverse events (AEs). METHODS: We first conducted a retrospective survey using a standardized data collection sheet for the clinical characteristics of PC-related AEs among 1096 patients collected in a prospective survey conducted between January 2013 and May 2014 (Cohort 1). Next, we retrospectively investigated additional AEs that occurred before and after Cohort 1 within the period June 2012 and December 2014 among 1482 patients (Cohort 2). RESULTS: Of the 2578 patients who underwent PC examinations from both cohorts, 74 AEs occurred among 61 patients (2.37%). The main AEs were residual parylene coating in 25 events (0.97%), PC-induced small bowel obstruction, suspicious of impaction, in 23 events (0.89%), and CE retention even after patency confirmation in 10 events (0.39%). Residual parylene coating was significantly associated with Crohn's disease (P < 0.01). Small bowel obstruction was significantly associated with physicians with less than 1 year of experience handling the PC and previous history of postprandial abdominal pain (P < 0.01 and P < 0.03, respectively). CE retention was ascribed to erroneous judgment of PC localization in all cases. CONCLUSIONS: This large-scale multicenter study provides evidence supporting the safety and efficiency of a PC to preclude CE retention. Accurate PC localization in patients without excretion and confirmation of previous history of postprandial abdominal pain before PC examinations is warranted (UMIN000010513).

Associations of personal urinary volatile organic compounds and lung function in children.

BACKGROUND: We investigated the correlation between urine VOC metabolites and airway function in children exposed to anthropogenic volatile organic compounds (VOCs), notable pollutants impacting respiratory health. METHODS: Out of 157 respondents, 141 completed skin prick tests, spirometry, IOS, and provided urine samples following the International Study of Asthma and Allergies in Childhood (ISAAC)-related questions. Allergic sensitization was assessed through skin prick tests, and airway functions were evaluated using spirometry and impulse oscillometry (IOS). Forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) was recorded and FEV1/FVC ratio was calculated. Airway mechanics parameters including respiratory resistance at 5 Hz (Rrs5) mean respiratory resistance between 5 Hz and 20 Hz (Rrs5-20), were also recorded. Urine concentrations of metabolites of benzene, ethylbenzene, toluene, xylene, styrene, formaldehyde, carbon-disulfide were analyzed by gas chromatography/tandem mass spectroscopy. RESULTS: The median age at study participation was 7.1 (SD 0.3) years. Muconic acid (benzene metabolites) and o-methyl-hippuric acid (xylene metabolites) above medians were associated with a significant increase in Rrs5 (muconic acid: aß = 0.150, p = .002; o-methyl-hippuric acid: aß = 0.143, p = .023) and a decrease in FEV1/FVC (o-methyl-hippuric acid: aß = 0.054, p = .028) compared to those below median. No associations were observed for Rrs5-20 and FEV1 between the groups categorized as above and below the median (all parameter p values > .05). CONCLUSIONS: Elevated levels of benzene and xylene metabolites were associated with a significant increase in Rrs5 and a decrease in FEV1/FVC, related to increased resistance and restrictive lung conditions compared to individuals with concentrations below the median.

Effect of toluene on m-xylene removal in a biotrickling filter: Performance, biofilm characteristics, and microbial analysis.

Hydrophobic volatile organic compounds (VOCs) pose a challenge to the removal efficiency in biotrickling filters (BTFs). The addition of relatively hydrophilic substances presents a promising approach for enhancing the elimination of hydrophobic VOCs. In this study, toluene was introduced into the BTF system alongside m-xylene, and their mixing ratios were changed to explore the interactions and mechanisms under different conditions. The result showed that the most pronounced synergistic interaction occurred when the mixing concentration ratio of m-xylene and toluene was 2:1. The removal efficiency (RE) of m-xylene increased from 88% to 97%, and the elimination capacity (EC) of m-xylene changed from 64 to 72 g m-3 h-1. Under this condition, there was a notable increase in biomass, extracellular polymeric substance (EPS) content, and relative hydrophobicity. Microbial diversity was enhanced observably with Berkeleyces and Mycobacterium potentially playing a positive role in co-degradation. Meanwhile, microbial metabolic function prediction indicated a significant enhancement in metabolic functions. Therefore, the introduction of relatively hydrophilic VOCs represents an effective strategy for enhancing the removal of hydrophobic VOCs in the BTFs.

Climatic conditions and concentrations of BTEX compounds in atmospheric media.

Climatic and meteorological conditions are among the factors affecting the ambient concentrations of BTEX compounds. This systematic review and meta-analysis aimed to interrogate the seasonal effect of climatic conditions on the concentrations of BTEX compounds. Three electronic bibliographic databases including Scopus, PubMed, and Web of Science were systematically searched up to November 14, 2023. The search algorithm followed PRISMA guidance and consisted of three groupings of keywords and their possible combinations. For various climatic conditions, the overall mean and 95% confidence interval (CI) of effect size related to BTEX concentrations were calculated using a random-effect model. In total, 104 articles were included for evaluation in this review. BTEX ambient concentration was higher in winter (ranging from 36 out of 79 relevant studies for xylene to 52 out of 97 relevant studies for benzene) followed by summer and autumn. For humidity conditions, the highest exposure values for BTEX were detected for rainy weather (ranging from 3 out of 5 relevant studies for toluene and xylene to 4 out of 5 relevant studies for benzene and ethyl benzene) compared to dry conditions. The pooled concentration (µg/m3) of benzene, toluene, ethyl benzene, and xylene were computed as 2.61, 7.12, 2.21, and 3.61 in spring, 2.13, 7.53, 1.61, and 2.75 in summer, 3.04, 9.59, 3.14, and 5.50 in autumn, and 3.56, 8.71, 2.35, and 3.91 in winter, respectively. Moreover, the pooled concentrations (µg/m3) of BTEX were measured as 2.98, 7.22, 1.90, and 3.03 in dry weather and 3.15, 6.30, 2.14, and 3.86 in rainy or wet weather, respectively. In most seasons, the ambient concentrations of BTEX were higher in countries with low and middle incomes and in Middle Eastern countries and East/Southeast Asia compared to those in other regions (P < 0.001). The increasing concentrations of BTEX in winter and autumn followed by the summer season and during rainy/wet weather appear to be reasonably consistent despite variations in study methods, quality, or geography. Therefore, it is recommended that more serious control measures are considered for decreasing exposure to BTEX in these climatic conditions.

Versatile ferrous oxidation-xylenol orange assay for high-throughput screening of lipoxygenase activity.

Lipoxygenases (LOXs) catalyze dioxygenation of polyunsaturated fatty acids (PUFAs) into fatty acid hydroperoxides (FAHPs), which can be further transformed into a number of value-added compounds. LOXs have garnered interest as biocatalysts for various industrial applications. Therefore, a high-throughput LOX activity assay is essential to evaluate their performance under different conditions. This study aimed to enhance the suitability of the ferrous-oxidized xylenol orange (FOX) assay for screening LOX activity across a wide pH range with different PUFAs. The narrow linear detection range of the standard FOX assay restricts its utility in screening LOX activity. To address this, the concentration of perchloric acid in the xylenol orange reagent was adjusted. The modified assay exhibited a fivefold expansion in the linear detection range for hydroperoxides and accommodated samples with pH values ranging from 3 to 10. The assay could quantify various hydroperoxide species, indicating its applicability in assessing LOX substrate preferences. Due to sensitivity to pH, buffer types, and hydroperoxide species, the assay required calibration using the respective standard compound diluted in the same buffer as the measured sample. The use of correction factors is suggested when financial constraints limit the use of FAHP standard compounds in routine LOX substrate preference analysis. FAHP quantification by the modified FOX assay aligned well with results obtained using the commonly used conjugated diene method, while offering a quicker and broader sample pH range assessment. Thus, the modified FOX assay can be used as a reliable high-throughput screening method for determining LOX activity. KEY POINTS: • Modifying perchloric acid level in FOX reagent expands its linear detection range • The modified FOX assay is applicable for screening LOX activity in a wide pH range • The modified FOX assay effectively assesses substrate specificity of LOX.

Association between blood volatile organic aromatic compound concentrations and hearing loss in US adults.

OBJECTIVE: Benzene, ethylbenzene, meta/para-xylene, and ortho-xylene, collectively referred to as benzene, ethylbenzene, and xylene (BEX), constitute the main components of volatile organic aromatic compounds (VOACs) and can have adverse effects on human health. The relationship between exposure to BEX and hearing loss (HL) in the adult U.S. population was aimed to be assessed. METHODS: Cross-sectional data from the National Health and Nutrition Examination Survey (NHANES) for the years 2003-2004, 2011-2012, and 2015-2016 were analyzed. This dataset included complete demographic characteristics, pure-tone audiometry measurements, and volatile organic compound detection data from the NHANES database. A weighted multivariate logistic regression model was employed to investigate the associations between blood BEX concentrations HL, low-frequency hearing loss (SFHL), and high-frequency hearing loss (HFHL). RESULTS: 2174 participants were included, with weighted prevalence rates of HL, SFHL, and HFHL being 46.81%, 25.23%, and 45.86%, respectively. Exposure to benzene, ethylbenzene, meta/para-xylene, and ortho-xylene, and cumulative BEX concentrations increased the risk of hearing loss (odds ratios [ORs] were 1.36, 1.22, 1.42, 1.23, and 1.31, respectively; all P < 0.05). In the analysis with SFHL as the outcome, ethylbenzene, m-/p-xylene, o-xylene, benzene, and overall BEX increased the risk (OR 1.26, 1.21, 1.28, 1.20, and 1.25, respectively; all P < 0.05). For HFHL, exposure to ethylbenzene, m-/p-xylene, o-xylene, benzene, and overall BEX increased the risk (OR 1.36, 1.22, 1.42, 1.22, and 1.31, respectively; all P < 0.05). CONCLUSION: Our study indicated that a positive correlation between individual or cumulative exposure to benzene, ethylbenzene, meta/para-xylene, and ortho-xylene and the risk of HL, SFHL, and HFHL. Further research is imperative to acquire a more comprehensive understanding of the mechanisms by which organic compounds, notably BEX, in causing hearing loss and to validate these findings in longitudinal environmental studies.

Association of the blood levels of specific volatile organic compounds with nonfatal cardio-cerebrovascular events in US adults.

BACKGROUND: Cardio-cerebrovascular diseases constitute a major global public health burden. Volatile organic compounds (VOCs) exposure has become progressively severe, endangering human health and becoming one of the main concerns in environmental pollution. The associations of VOCs exposure with nonfatal cardio-cerebrovascular events have not been identified in observational study with a large sample size, so we aim to examine the association in US adult population. METHODS: Adults aged > 18 years with complete data regarding selected blood levels of VOCs (including benzene, ethylbenzene, o-xylene, and m-/p-xylene) and nonfatal cardio-cerebrovascular events were included in the analysis (n = 3,968, National Health and Nutrition Examination Survey, NHANES, 2013-2018 survey cycle). Participants were classified into low- and high-exposure based on whether above selected VOCs low limit detect concentration or median value. Weighted multivariate logistic analyses and subgroup analyses were used to detect the association between selected VOCs exposure and nonfatal cardio-cerebrovascular events in US adults. RESULTS: Weighted multivariate logistic analyses showed that the high-VOCs exposure group had an increased risk of nonfatal cardio-cerebrovascular events compared with the low-VOCs exposure group; the adjusted odds ratios (OR) and 95% confidence intervals (CI) of nonfatal cardio-cerebrovascular events for the high-VOCs exposure group were 1.41 (0.91, 2.19), 1.37 (0.96, 1.95), 1.32 (0.96, 1.82), and 1.17 (0.82, 1.67) for benzene, ethylbenzene, o-xylene, and m-/p-xylene, respectively, which was not significant assuming statistical significance at a 0.05 significance level (95% CI) for a two-tailed test. Lastly, we found high-VOCs exposure was associated with increased incidence of nonfatal cardio-cerebrovascular events in both daily smokers an non-daily smokers (p-interaction > 0.01), but the association was not statistically significant in non-daily smokers. CONCLUSIONS: This study found that VOCs (benzene, ethylbenzene, o-xylene, and m-/p-xylene) exposure was associated with increased incidence of nonfatal cardio-cerebrovascular events in US adults, and the results need to be confirmed by larger cohort studies.

Glutamic-Alanine Rich Glycoprotein from Undaria pinnatifida: A Promising Natural Anti-Inflammatory Agent.

This study aimed to assess the anti-inflammatory properties of a bioactive glutamic-alanine rich glycoprotein (GP) derived from Undaria pinnatifida on both LPS-stimulated RAW264.7 cells, peritoneal macrophages, and mouse models of carrageenan- and xylene-induced inflammation, investigating the underlying molecular mechanisms. In both in-vitro and in-vivo settings, GP was found to reduce the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) while also inhibiting the production of nitric oxide (NO) and prostaglandin E2 (PGE2) in response to lipopolysaccharide (LPS) stimulation. GP treatment significantly impeded the nuclear translocation of the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathway by blocking the phosphorylation of IKKα and IκBα, leading to a reduction in proinflammatory cytokines such as tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß), and interleukin-6 (IL-6). Additionally, GP effectively inhibited the activation of mitogen-activated protein kinases (MAPKs), with specific inhibitors of p38 and extra-cellular signal regulated kinase (ERK) enhancing GP's anti-inflammatory efficacy. Notably, GP administration at 10 mg/kg/day (p.o.) markedly reduced carrageenan-induced paw inflammation and xylene-induced ear edema by preventing the infiltration of inflammatory cells into targeted tissues. GP treatment also downregulated key inflammatory markers, including iNOS, COX-2, IκBα, and NF-κB, by suppressing the phosphorylation of p38 and ERK, thereby improving the inflammatory index in both carrageenan- and xylene-induced mouse models. These findings suggest that marine resources, particularly seaweeds like U. pinnatifida, could serve as valuable sources of natural anti-inflammatory proteins for the effective treatment of inflammation and related conditions.

Exploring the microbe-mediated biological processes of BTEX and toxic metal(loid)s in aging petrochemical landfills.

Aging petrochemical landfills serve as reservoirs of inorganic and organic contaminants, posing potential risks of contamination to the surrounding environment. Identifying the pollution characteristics and elucidating the translocation/ transformation processes of typical contaminants in aging petrochemical landfills are crucial yet challenging endeavors. In this study, we employed a combination of chemical analysis and microbial metagenomic technologies to investigate the pollution characteristics of benzene, toluene, ethylbenzene, and xylene (BTEX) as well as metal(loid)s in a representative aging landfill, surrounding soils, and underlying groundwater. Furthermore, we aimed to explore their transformations driven by microbial activity. Our findings revealed widespread distribution of metal(loid)s, including Cd, Ni, Cu, As, Mn, Pb, and Zn, in these environmental media, surpassing soil background values and posing potential ecological risks. Additionally, microbial processes were observed to contribute significantly to the degradation of BTEX compounds and the transformation of metal(loid)s in landfills and surrounding soils, with identified microbial communities and functions playing key roles. Notably, co-occurrence network analysis unveiled the coexistence of functional genes associated with BTEX degradation and metal(loid) transformation, driven primarily by As, Ni, and Cd. These results shed light on the co-selection of resistance traits against BTEX and metal(loid) contaminants in soil microbial consortia under co-contamination scenarios, supporting microbial adaptive evolution in aging petrochemical landfills. The insights gained from this study enhance our understanding of characteristic pollutants and microbial transformation processes in aging landfills, thereby facilitating improved landfill management and contamination remediation strategies.

Volatile organic compounds and cancer risk assessment in an intensive care unit.

Changes caused by air-cleaning devices in the amounts of volatile organic compounds in an intensive care unit were monitored in the study. The cancer risk and hazard index were calculated. The measurements were made for one month at isolated room and two different points and times in the intensive care unit. According to the sampling program, the air-cleaning devices were turned off in weeks 1 and 4 and turned on in weeks 2 and 3. Volatile organic compounds were collected by active sampling. Samples were analyzed by a thermal desorber coupled to a gas chromatography-mass spectrometry instrument with selective ion monitoring. The results showed that the concentrations of benzene, toluene, and o-xylene decreased by about 70% after the air-cleaning devices were installed. The cancer risk assessment for naphthalene was recorded at the highest level of cancer risk (Class A). The hazard index value of naphthalene was recorded at the harmful level when air-cleaning devices were not installed. The concentrations of benzene (p = 0.01), toluene (p = 0.02), ethylbenzene (p = 0.02), styrene (p = 0.01), and m, p-xylene (p = 0.04) before the air-cleaning devices were installed were significantly different from those recorded when the air-cleaning devices were turned on.

Health risk assessment of exposure to benzene, toluene, ethyl benzene, and xylene in shoe industry-related workplaces.

Benzene, toluene, ethyl benzene, and xylene (BTEX) are prevalent pollutants in shoe industry-related workplaces. The aim of this study was to assess exposure to BTEX and their carcinogenic and non-carcinogenic risks in shoe-industry-related workplaces. This study was carried out at different shoe manufactures, small shoe workshop units, shoe markets, and shoe stores in Tabriz, Iran in 2021. Personal inhalation exposure to BTEX was measured using the National Institute for Occupational Safety and Health (NIOSH) 1501 method. Carcinogenic and non-carcinogenic risks due to inhalation exposure to BTEX were estimated by United States Environmental Protection Agency (U.S. EPA) method based on Mont Carlo simulation. Results showed that the concentrations of benzene and toluene were higher than the threshold limit value (TLV) in both gluing and non-gluing units of shoe manufactures. The total carcinogenic risk (TCR) due to exposure to benzene and ethyl benzene was considerable in all shoe industry-related workplaces. Also, the hazard index (HI) as a non-carcinogenic index was higher than standard levels in all shoe industry-related workplaces. Therefore, shoe industry-related workers are at cancer and non-cancer risks due to exposure to BTEX. Prevention measures need to be implemented to reduce the concentration of BTEX in shoe industry-related workplaces.

Impact of xylene exposure during organogenesis on foeto-placental efficiency and foetal viability: Exploring its association with oxidative stress-induced inflammation and apoptosis in utero.

The potential maternal and foetal toxicity resulting from exposure to xylene at or below the allowable limit of 100 ppm during gestation is not thoroughly studied. The aim of this study was to investigate maternal and foetal outcomes following prenatal exposure to xylene during organogenesis. Pregnant Sprague Dawley (SD) rats were administered intraperitoneal (IP) corn oil (vehicle), 100, 500, and 1000 parts per million (ppm) of xylene from gestational day (GD) 6 until GD17. Clinical signs, maternal weight gain, and food consumption were recorded daily. A caesarean hysterectomy was performed on GD21 to assess the reproductive and foetal outcomes. Exposure to 1000 ppm of xylene caused a significant decrease in the maternal body weight and food consumption, and an increase in intrauterine foetal deaths. Foetal assessment revealed a significant decrease in foetal weight in both male and female foetuses of female rats treated with 500 and 1000 ppm. Male placental weight was significantly decreased in all xylene-treated groups, while 1000 ppm xylene significantly decreased female placental weight. Histologically, marked uterine inflammatory lesions, fibrosis of the liver and renal tissues, as well as increased placental glycogen content were observed. Immunohistochemistry revealed a significant increase in lipid peroxidation and apoptotic markers. Thus, the foeto-maternal toxicities of xylene have been shown to be mediated by a systemic inflammatory response that exacerbates intrauterine oxidative stress and impairs foeto-placental transfer, leading to an increase in foetal mortality.

High-performance activation of ozone by sonocavitation for BTEX degradation in water.

This work presents a novel advanced oxidation process (AOP) for degradation of emerging organic pollutants - benzene, toluene, ethylbenzene and xylenes (BTEXs) in water. A comparative study was performed for sonocavitation assisted ozonation under 40-120 kHz and 80-200 kHz dual frequency ultrasounds (DFUS). Based on the obtained results, the combination of 40-120 kHz i.e., low-frequency US (LFDUS) with O3 exhibited excellent oxidation capacity degrading 99.37-99.69% of BTEXs in 40 min, while 86.09-91.76% of BTEX degradation was achieved after 60 min in 80-200 kHz i.e., high-frequency US (HFDUS) combined with O3. The synergistic indexes determined using degradation rate constants were found as 7.86 and 2.9 for LFDUS/O3 and HFDUS/O3 processes, respectively. The higher extend of BTEX degradation in both processes was observed at pH 6.5 and 10. Among the reactive oxygen species (ROSs), hydroxyl radicals (HO•) were found predominant according to scavenging tests, singlet oxygen also importantly contributed in degradation, while O2•- radicals had a minor contribution. Sulfate (SO42-) ions demonstrated higher inhibitory effect compared to chloride (Cl-) and carbonate (CO32-) ions in both processes. Degradation pathways of BTEX was proposed based on the intermediates identified using GC-MS technique.

Source differentiation of BTEX compounds in groundwater contaminated due to refinery activities.

This study aims to identify sources of groundwater contamination in a refinery area using integrated compound-specific stable isotope analysis (CSIA), oil fingerprinting techniques, hydrogeological data, and distillation analysis. The investigations focused on determination of the origin of benzene, toluene, ethylbenzene, and xylenes (BTEX), and aliphatic hydrocarbons as well. Groundwater and floating oil samples were collected from extraction wells for analysis. Results indicate presence of active leaks in both the northern and southern zones. In the northern zone, toluene was found to primarily originate from oil products like aviation turbine kerosene (ATK or aviation fuel), kerosene, regular gasoline, and diesel fuel. Additionally, stable isotope ratios of carbon and hydrogen for ethylbenzene, o-xylene (ortho xylene) and p-xylene (para xylene) in zone A suggested the pollution originated from gasoline within the northern zone. The origin of super gasoline (with higher octane) identified in southern zone using δ13C and δ2H values of toluene in the floating oil and groundwater samples. Further, biodegradation of toluene likely occurred in southern zone according to δ13C and δ2H. The findings underscore the critical importance of integrating CSIA and fingerprinting techniques to effectively address the challenges of source identification and relying solely on each method independently is insufficient. Accordingly, comparing the GC-MS results of floating oil samples with ATK and jet fuel (JP4) standards can be effectively utilized for source differentiation. However, this method showed no practical application to distinguish different types of diesel or gasoline. The accuracy and reliability of source identification of BTEX compounds may significantly improve when hydrogeological data incorporates with stable isotopes analysis. Additionally, the results of this study will elevate the procedures for fuel-related contaminants source identification of the polluted groundwater that is crucial to develop effective remediation strategies.

Packing Incubation and Addition of Rot Fungi Extracts Improve BTEX Elimination from Air in Biotrickling Filters.

The removal of benzene, toluene, ethylbenzene, and xylene (BTEX) from air was investigated in two similar biotrickling filters (BTFs) packed with polyurethane (PU) foam, differing in terms of inoculation procedure (BTF A was packed with pre-incubated PU discs, and BTF B was inoculated via the continuous recirculation of a liquid inoculum). The effects of white rot fungi enzyme extract addition and system responses to variable VOC loading, liquid trickling patterns, and pH were studied. Positive effects of both packing incubation and enzyme addition on biotrickling filtration performance were identified. BFF A exhibited a shorter start-up period (approximately 20 days) and lower pressure drop (75 ± 6 mm H2O) than BTF B (30 days; 86 ± 5 mm H2O), indicating the superior effects of packing incubation over inoculum circulation during the biotrickling filter start-up. The novel approach of using white rot fungi extracts resulted in fast system recovery and enhanced process performance after the BTF acidification episode. Average BTEX elimination capacities of 28.8 ± 0.4 g/(m3 h) and 23.1 ± 0.4 g/(m3 h) were reached for BTF A and BTF B, respectively. This study presents new strategies for controlling and improving the abatement of BTEX in biotrickling filters.

The impact of ozone treatment on the removal effectiveness of various refractory compounds in wastewater from petroleum refineries.

Large volumes of wastewater are generated during petroleum refining processes. Petroleum refinery wastewater (PRW) can contain highly toxic compounds that can harm the environment. These toxic compounds can be a challenge in biological treatment technologies due to the effects of these compounds on microorganisms. These challenges can be overcome by using ozone (O3) as a standalone or as a pretreatment to the biological treatment. Ozone was used in this study to degrade the organic pollutants in the heavily contaminated PRW from a refinery in Mpumalanga province of South Africa. The objective was achieved by treating the raw PRW using ozone at different ozone treatment times (15, 30, 45, and 60 min) at a fixed ozone concentration of 3.53 mg/dm3. The ozone treatment was carried out in a 2-liter custom-designed plexiglass cylindrical reactor. Ozone was generated from an Eco-Lab-24 corona discharge ozone generator using clean, dry air from the Afrox air cylinder as feed. The chemical oxygen demand, gas chromatograph characterization, and pH analysis were performed on the pretreated and post-treated PRW samples to ascertain the impact of the ozone treatment. The ozone treatment was effective in reducing the benzene, toluene, ethylbenzene, and xylenes (BTEX) compounds in the PRW. The 60-min ozone treatment of different BTEX pollutants in the PRW resulted in the following percentage reduction: benzene 95%, toluene 77%, m + p-xylene 70%, ethylbenzene 69%, and o-xylene 65%. This study has shown the success of using ozone in reducing the toxic BTEX compounds in a heavily contaminated PRW.

Production of Biobased Ethylbenzene by Cascade Biocatalysis with an Engineered Photodecarboxylase.

Production of commodity chemicals, such as benzene, toluene, ethylbenzene, and xylenes (BTEX), from renewable resources is key for a sustainable society. Biocatalysis enables one-pot multistep transformation of bioresources under mild conditions, yet it is often limited to biochemicals. Herein, we developed a non-natural three-enzyme cascade for one-pot conversion of biobased l-phenylalanine into ethylbenzene. The key rate-limiting photodecarboxylase was subjected to structure-guided semirational engineering, and a triple mutant CvFAP(Y466T/P460A/G462I) was obtained with a 6.3-fold higher productivity. With this improved photodecarboxylase, an optimized two-cell sequential process was developed to convert l-phenylalanine into ethylbenzene with 82 % conversion. The cascade reaction was integrated with fermentation to achieve the one-pot bioproduction of ethylbenzene from biobased glycerol, demonstrating the potential of cascade biocatalysis plus enzyme engineering for the production of biobased commodity chemicals.

Water potential governs the effector specificity of the transcriptional regulator XylR of Pseudomonas putida.

The biodegradative capacity of bacteria in their natural habitats is affected by water availability. In this work, we have examined the activity and effector specificity of the transcriptional regulator XylR of the TOL plasmid pWW0 of Pseudomonas putida mt-2 for biodegradation of m-xylene when external water potential was manipulated with polyethylene glycol PEG8000. By using non-disruptive luxCDEAB reporter technology, we noticed that the promoter activated by XylR (Pu) restricted its activity and the regulator became more effector-specific towards head TOL substrates when cells were grown under water subsaturation. Such a tight specificity brought about by water limitation was relaxed when intracellular osmotic stress was counteracted by the external addition of the compatible solute glycine betaine. With these facts in hand, XylR variants isolated earlier as effector-specificity responders to the non-substrate 1,2,4-trichlorobenzene under high matric stress were re-examined and found to be unaffected by water potential in vivo. All these phenomena could be ultimately explained as the result of water potential-dependent conformational changes in the A domain of XylR and its effector-binding pocket, as suggested by AlphaFold prediction of protein structures. The consequences of this scenario for the evolution of specificities in regulators and the emergence of catabolic pathways are discussed.