Search

Epidemiological studies have proven that children mental health can be affected by environmental pollutants which are believed to be visible in the form of psychological disorder later in their childhood. Moreover, the effects of children mental health are evidently clear in the case of phthalates which have been observed to increase psychological disorder, specifically attention-deficit hyperactivity disorder (ADHD). Hence, the present study aims to conduct a systematic review and provide an overview of the existing literature on the association between urinary phthalate metabolite concentrations and ADHD symptoms among children by emphasizing the confounding factors and limitations. Additionally, this review addressed the possible phthalate mechanism insights in human body including its impact on ADHD symptoms. In this case, 16 epidemiological studies (five cross-sectional, nine cohort and two case control studies) that met all the inclusion criteria were selected out of the total of 427 papers screened to show varying quantitative associations between phthalate exposure and ADHD symptoms among children with confounding factors and limitations in the existing studies in regard to the exposure and outcomes. This review also attempted to present possible explanation on phthalate mechanism in children body and its connection on neurodevelopment and ADHD symptom development which remains unclear in most of the studies. Finally, it is highly recommended for further research to carefully design cohort studies from prenatal to later childhood development with a complete sample size in order to understand phthalate impacts on children health.

While the antibacterial effect of silver nanoparticles (AgNPs) on environmentally beneficial microbes has drawn considerable attention, the stability and microbial toxicity of AgNPs in a system where nitrate reduction is the dominant terminal electron-accepting process remain understudied. Here, we explore the impact of citrate-coated AgNPs (cit-AgNPs) on the growth and metabolism of two metal-sensitive and one nonsensitive bacterial strains under denitrifying conditions. Dose-response analysis revealed that in contrast to the bacteriostatic effect exhibited at 1 ppm, 5 ppm cit-AgNPs were bactericidal to the metal-sensitive strains. It was observed that the growth of the cells initiated Ag(I) formation, and the supplement of chloride (2.7 mM) to the cultures substantially mitigated the bactericidal capacity of cit-AgNPs, indicating that AgNP dissolution to ionic Ag(I) played a key role in AgNP toxicity. Abiotic experiments confirmed that nitrite, not nitrate, had the capacity to oxidize cit-AgNPs. Transcriptomic analysis revealed that (i) the gene encoding for membrane stress was upregulated proportionally to cit-AgNP concentrations; (ii) cit-AgNPs and Ag(I) at higher levels upregulated genes involved in oxidative stress and iron-sulfur clusters, whereas expressions of the genes responsible for electron transport, ATP synthesis, and denitrification were substantially repressed; (iii) the addition of chloride significantly altered the level of transcriptional profiles of all of the genes. These results not only provide evidence of abiotic AgNP oxidation by metabolic intermediate nitrogen species but also suggest that AgNPs and Ag(I) may induce differential toxicity modes to prokaryotes. Our findings reinforce the importance of evaluating the potential ecological toxicity and risks associated with the transformation of nanomaterials.

Chloroethenes are common groundwater pollutants, and have been classified as toxic and carcinogenic to humans. The metabolites of chloroethenes, cis-dichloroethene (cis-DCE) and vinyl chloride (VC) commonly accumulate in groundwater due to their recalcitrant reductive dechlorination under anaerobic conditions. Dehalococcoides mccartyi (Dhc) is the key anaerobic bacteria for complete dechlorination of chloroethene, and Clostridium butyricum (C. butyricum) can provide hydrogen for supporting the growth of Dhc. In this study, we co-immobilized Dhc strain BAV1 and C. butyricum in a silica gel to determine the ability of the complete dechlorination of cis-DCE. Our results showed that our immobilized system could protect BAV1 from a high concentration (8 mM) of cis-DCE to carry out complete dechlorination. After the long-term use of our immobilized system, the activity of complete dechlorination was maintained for more than 180 consecutive days. Furthermore, we applied the immobilized system to remediate contaminated groundwater and uncovered the complete dechlorination of cis-DCE into ethene, a non-toxic product, within 28 days. Therefore, this novel co-immobilized system could serve a solution for bioremediation at chloroethene-contaminated sites.

In-situ sorbent amendment is a relatively low-cost, low-impact approach for remediation of soil contaminated with heavy metals (HMs), and thus is considered a way to be favored in developing countries. In this study, materials of non-hazardous, alkaline agronomic and industrial by-products were used as sorbents to explore their capacity of in situ immobilization of multiple HMs in mining-impacted arable soil. These sorbents included fly ash (FA), biochar (BC) and apatite (AP) and they were implemented with varying ratios of combinations. Results of soil microcosm tests showed that after incubation for 90 days, concentrations of Pb, Zn, and Cd in their exchangeable forms determined by a sequential extraction method significantly decreased in amended soils, as opposed to the unamended control. Of the five sets of amendments, the composite of FA, BC, and AP resulted in the maximum reduction (up to 80%) in the mobility of Pb, Zn, and Cd in soils. The mechanisms underlying the immobilization of HMs in amended soils might involve processes of surface precipitation, ion exchange and complexation, in which the physicochemical properties of sorbent materials played an important role. The immobilization efficacy of sorbent amendments on HMs in soil was further supported by pot experiments in which significant inhibition of HM accumulation in the belowground and aboveground tissues of maize was observed after 50-day cultivation in amended soils as compared with control soil. Together, these results suggest that the application of cost-saving and environmentally friendly materials derived from wastes as sorbents to remediate soils contaminated with multiple HMs is promising for developing countries like Vietnam.

High ammonium concentration in groundwater represents a major public health concern in Hanoi, Vietnam. In this study, mesoporous activated carbon was prepared from corncob using H3PO4 through a one-stage chemical activation process. Corncob activated carbon (CCAC) was subsequently treated with NaOH to enhance its cation exchange capacity. The results showed that this NaOH-modified corncob activated carbon (M-CCAC) exhibited a large specific surface area (1097 m2/g) and high total pore and mesopore volumes (0.804 cm3/g and 0.589 cm3/g, respectively). The batch experiments indicated that the NH4+-N removal was strongly dependent on the coexisting cations and pH of the solution, while in the kinetic experiments adsorption equilibrium was quickly reached within 60 min. The activation energy was calculated to be 49.7 kJ/mol. The maximum Langmuir adsorption capacity of M-CCAC exhibited the following order: 17.03 mg/g at 20 °C > 15.4 mg/g at 35 °C > 11.99 mg/g at 50 °C. The NH4+ adsorption process was spontaneous (–ΔG°) and exothermic (–ΔH°), and it increased the randomness (+ΔS°) in the system. The column experiments were conducted using real underground water to analyze the effects of different flow rates (1–3 mL/min), influent concentrations (10–40 mg/L), and bed heights (8.07–23.9 cm) on the adsorption capacity. The maximum adsorption capacity (8.69 mg/g) was achieved at a flow rate of 2 mL/min, an initial concentration of 40 mg/L, and a column height of 15.8 cm. Ion exchange was found to be the principal mechanism that controls ammonium adsorption, while pore-filling and electrostatic attraction played minor roles in the process. This study proved that M-CCAC is an effective adsorbent to remove ammonium from real groundwater.

Mg/Al layered double hydroxides (LDH) directly intercalated with organic anions (citrate and malate) were synthesized through a co-precipitation method at low supersaturation, yielding Citrate-LDH and Malate-LDH, respectively. Three obtained LDH samples were characterized using X-ray diffraction, Fourier transform infrared spectroscopy, zeta potential, and scanning electron microscopy. The results indicated that the organic anions were intercalated into the interlayer region of LDH as a horizontal orientation. The adsorption capacity of the LDH samples toward Cu(II) and Pb(II) ions was strongly affected by the solution’ pH, with the highest adsorption capacity reaching at pH 5.0. As revealed in the kinetic study, equilibrium was rapidly established with adsorption half-lives at 30 °C in the range of 7.38–11.4 min for Cu(II) adsorption and 1.59–3.87 min for Pb(II) adsorption. The maximum Langmuir adsorption capacity of Pb(II) and Cu(II) cations at 30 °C exhibited the following order: Citrate-LDH (166 mg/g and 137 mg/g) > Malate-LDH (141 mg/g and 118 mg/g) > pristine LDH (84.7 mg/g and 59.9 mg/g), respectively. Thermodynamic studies demonstrated that the adsorption process was spontaneous (−ΔG°), endothermic (+ΔH°), and increasingly random (+ΔS°). The results demonstrated that the intercalation of citrate and malate anions into LDH successfully resulted in improving the adsorption capacity and rate of potentially toxic cations.

Mg/Al layered double hydroxides (Mg/Al-LDHs) directly intercalated with different amino acids (phenylalanine, tyrosine, and serine) were synthesized through a co-precipitation method, yielding Phenylalanine-LDH, Tyrosine-LDH, and Serine-LDH, respectively. The obtained LDHs were characterized with X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy. The results indicated that the tested amino acids were intercalated into the interlayer region of Mg/Al-LDH as a horizontal orientation and monolayer arrangement. The abundant presence of anions (CO 3 2− and NO 3 − ) in the interlayer region of LDHs plays an important role in the removal process of toxic metal ions. The adsorption results demonstrated that Phenylalanine-LDH exhibited the excellent maximum adsorption capacity ( Q o max ) to cations, with the sorption capacity sequence: Cu 2+ (7.223 mmol/g) > Pb 2+ (4.112 mmol/g) > Ni 2+ (2.368 mmol/g) > Cd 2+ (1.966 mmol/g), while the highest Q o max (2.901 mmol/g) was obtained by Tyrosine-LDH for oxyanion adsorption. The Q o max values of pristine Mg/Al-LDH followed the order: Ni 2+ (1.366 mmol/g) > Cu 2+ (1.248 mmol/g) > Cd 2+ (0.961 mmol/g) > Pb 2+ (0.627 mmol/g) > MnO 4 − (0.509 mmol/g). Electrostatic attraction was found to be the principal mechanism that controls the adsorption of potentially toxic metals. This study proved that amino acids-intercalated LDHs are promising dual-electronic adsorbents for the simultaneous removal of cationic and oxyanionic metal ions from water media.

4-t-Octylphenol (4-t-OP) has become a serious environmental concern due to the endocrine disruption in animals and humans. The biodegradation of 4-t-OP by pure cultures has been extensively investigated only in bacteria and wood-decaying fungi. In this study we isolated and identified 14 filamentous fungal strains from wastewater samples in Taiwan using 4-t-OP as a sole carbon and energy source. The isolates were identified based on sequences from different DNA regions. Of 14 fungal isolates, 10 strains grew effectively on solid medium with a wide variety of endocrine disrupting chemicals as the sole carbon and energy source. As revealed by high-performance liquid chromatography analysis, the most effective 4-t-OP degradation (> 70%) in liquid medium was observed in Fusarium falciforme after 15 days. To our knowledge, this is the first report on the degradation of 4-t-OP as a sole carbon and energy source by non-ligninolytic fungi.

Epidemiological studies have proven that children mental health can be affected by environmental pollutants which are believed to be visible in the form of psychological disorder later in their childhood. Moreover, the effects of children mental health are evidently clear in the case of phthalates which have been observed to increase psychological disorder, specifically attention-deficit hyperactivity disorder (ADHD). Hence, the present study aims to conduct a systematic review and provide an overview of the existing literature on the association between urinary phthalate metabolite concentrations and ADHD symptoms among children by emphasizing the confounding factors and limitations. Additionally, this review addressed the possible phthalate mechanism insights in human body including its impact on ADHD symptoms. In this case, 16 epidemiological studies (five cross-sectional, nine cohort and two case control studies) that met all the inclusion criteria were selected out of the total of 427 papers screened to show varying quantitative associations between phthalate exposure and ADHD symptoms among children with confounding factors and limitations in the existing studies in regard to the exposure and outcomes. This review also attempted to present possible explanation on phthalate mechanism in children body and its connection on neurodevelopment and ADHD symptom development which remains unclear in most of the studies. Finally, it is highly recommended for further research to carefully design cohort studies from prenatal to later childhood development with a complete sample size in order to understand phthalate impacts on children health.

Recycling materials from waste has been considered one of the essential principles in the context of sustainable development. In this study, we used teak sawdust as the feedstock material to synthesize activated carbon (AC) samples and evaluated the application of these ACs in the adsorption of methylene blue (MB), Cd(II), and Cu(II). The sawdust was carbonized by a hydrothermal process, followed by chemical activation using K2CO3 or ZnCl2 in various weight ratios. The AC samples produced were characterized by scanning electron microscopy, Brunauer&ndash, Emmett&ndash, Teller surface area analysis, Fourier-transform infrared spectroscopy, X-ray photon spectroscopy, and mass titration of acidic groups. The characterization results showed that the ACs did possess a high surface area and rich oxygen-containing functional groups. The adsorptive amounts of MB, Cd(II), and Cu(II) on ACs approximately increased with the concentration of the activating agent: when the weight ratio of the carbonaceous material to ZnCl2 reached 1.75, the maximum adsorption capacities for MB, Cd(II), and Cu(II) were achieved, and the values were 614, 208, and 182 mg/g, respectively. The level of oxygen-containing functional groups was identified as an important factor in determining the adsorptive amounts. While the electrostatic force was the primary pathway that led to the adsorption of the tested contaminants onto the AC, the complexation reaction was a vital mechanism responsible for the adsorptive interaction between ACs and Cu(II). The high adsorption capacity of the synthetic ACs for MB, Cd(II), and Cu(II) demonstrated in this study points out the potential application of biomass-residue-based adsorbents prepared via a coupled hydrothermal carbonization/chemical activation process in wastewater treatment.

While earlier studies have identified the antibacterial activity of carbon nanotubes (CNTs) and proposed that cell membrane damage by direct contact with CNTs is likely the main toxicity mechanism, the relative importance of chemical versus physical properties of CNTs in controlling their bacterial cytotoxicity is understudied. Given that CNT is commonly modified via acid treatment to enhance its dispersivity and surface chemistry, in this study commercially available multi-walled carbon nanotubes (MWCNTs) with high purity were processed carefully by acid reflux, resulting in differences in surface charge of MWCNTs without altering their physical properties. The surface condition of MWCNTs was also modified by adsorption of organic matter to compare bacterial toxicity of functionalized and non-functionalized MWCNTs in suspensions. Results show that although overall electrostatic repulsion and steric obstruction resulted from surface modifications led to elevated dispersivity of MWCNTs and mitigated toxicity on planktonic Escherichia coli cultures, no correlation between the dispersivity and bacterial toxicity of MWCNTs was observed, suggesting that dispersity alone may not be a proper index to estimate the CNT antibacterial effect on planktonic cells in the aqueous phase. In addition, viability recovery of MWCNT-treated cells was observed to be nutrition level-dependent, implying that availability of proper nutrients may be another important factor to be considered when assessing the ecotoxicity of CNTs in the aquatic system.

In this study, a catalyst derived from iron slag (Fe-S) was used for heterogeneous Fenton oxidation (H 2 O2/Fe-S) of paracetamol in aqueous solution; the conventional homogeneous Fenton reaction (H 2 O2/Fe2＋) was run in parallel for comparison. Degradation of paracetamol, in terms of chemical oxygen demand (COD) removal, was found strongly dependent on the solution pH, with the maximum efficiency obtained at pH 3 for both H 2 O2/Fe-S and H 2 O2/Fe2＋ systems. The efficacy of paracetamol degradation was also affected by the ratio (w/w) of hydrogen peroxide to iron, as the maxima degradation was observed at ratios of 1:2 and 2:1 for the heterogeneous and homogeneous Fenton, respectively. In addition, the degradation efficiency decreased when the initial paracetamol concentration increased from 100 mg/L to 500 mg/L. Kinetic experiments showed that degradation of paracetamol fitted a pseudo-first-order kinetic model well, as evidenced by the K d values of the pseudo-first-order kinetic model that followed the same sequence as the degradation efficiency of paracetamol. Processes involved in the degradation of paracetamol by H 2 O2/Fe-S mainly included adsorption and oxidation; for latter, the presence of FeO, ZnO, and SiO2 in Fe-S constituent might enhance the decomposition of H 2 O2 and generate more *OH radicals. The *OH radical-mediated oxidation was confirmed by significant declines in the elimination of paracetamol when the system was subject to various radical-scavengers including t-butanol, chloride, and carbonate species.

Supplemental Material for Effect of nitric acid oxidation on the surface of hydrochars to sorb methylene blue: An adsorption mechanism comparison by Duy H Nguyen, Hai Nguyen Tran, Huan-Ping Chao and Chu-Ching Lin in Adsorption Science & Technology

4-t-octylphenol (4-t-OP), a well-known endocrine disrupting compound, is frequently found in various environmental compartments at levels that may cause adverse effects to the ecosystem and public health. To date, most of the studies that investigate microbial transformations of 4-t-OP have focused on the process mediated by bacteria, ligninolytic fungi, or microbial consortia. There is no report on the complete degradation mechanism of 4-t-OP by non-ligninolytic fungi. In this study, we conducted laboratory experiments to explore and characterize the non-ligninolytic fungal strain Fusarium falciforme RRK20 to degrade 4-t-OP. Using the response surface methodology, the initial biomass concentration and temperature were the factors identified to be more influential on the efficiency of the biodegradation process as compared with pH. Under the optimized conditions (i.e., 28 °C, pH 6.5 with an initial inoculum density of 0.6 g L−1), 25 mg L−1 4-t-OP served as sole carbon source was completely depleted within a 14-d incubation; addition of low dosage of glucose was shown to significantly accelerate 4-t-OP degradation. The yeast estrogenic screening assay further confirmed the loss of estrogenic activity during the biodegradation process, though a longer incubation period was required for complete removal of estrogenicity. Metabolites identified by LC-MS/MS revealed that strain RRK20 might degrade 4-t-OP as sole energy source via alkyl chain oxidation and aromatic ring hydroxylation pathways. Together, these results not only suggest the potential use of non-ligninolytic fungi like strain RRK20 in remediation of 4-t-OP contaminated environments but may also improve our understanding of the environmental fate of 4-t-OP.

In Taiwan, because of the co-use of some irrigation and drainage canals, a portion of industrial wastewater was directly discharged into irrigation canals or even flowed into rivers or wetlands, causing the heavy metal pollution in waters and sediments. Mercury (Hg) contamination in rivers, irrigation canals, and wetlands has been found in Taiwan, but a thorough investigation on the distribution of Hg and methylmercury (MeHg) in these waters and sediments, which may be present in a greater level with elevating total Hg (THg) concentration and markedly impact human health, is still lacking. In this study, surface waters and surface sediments were sampled from five major rivers, two irrigation canals, two reservoirs, and one wetland in Taiwan, and their THg and MeHg concentrations were quantified. Additionally, statistical analysis was carried out to understand the relationship between sediment properties and MeHg levels. The results showed that irrigation canal sediments were relatively more polluted by Hg and the THg concentrations of some sampling points exceeded the upper limit (i.e., 0.87 mg kg−1) of sediment quality index (SQI) for THg promulgated by Taiwan Environmental Protection Administration, which may be attributed to the co-use of irrigation and drainage canals. Furthermore, the MeHg concentration in irrigation canal sediments was the highest; rivers came in second followed by wetlands. In addition, the Siangshan Wetland was analyzed to have the greatest THg and MeHg concentrations in its surface water. Linear regression analysis also indicated that total organic carbon and clay content substantially affected the MeHg production in sediments.

Long-chain alkylphenols including octylphenol (OP) are well-known toxic pollutants prevailing in the environment due to the massive demand of these chemicals in industry and have been identified as endocrine disrupting chemicals (EDCs). While a considerable amount of work has addressed the degradation capacity of EDCs carried out by bacterial and filamentous fungal strains, little is known about the EDC degradation by yeasts. In this study, we isolated three branched-chain OP-degrading yeast strains from samples collected from a wastewater treatment plant in Taipei, Taiwan, by enrichment methods using 4-t-octylphenol (4-t-OP) as the sole carbon and energy source. Analysis of ITS and LSU rDNA gene sequences revealed that these isolates belonged to two genera and were designated as Candida rugopelliculosa RRKY5, Galactomyces candidum RRK17 and G. candidum RRK22. Growth properties of the isolates were explored using different substrates such as 4-t-OP, 4-t-nonylphenol (4-t-NP), octylphenol polyethoxylates (OPEOn), nonylphenol polyethoxylates (NPEOn), phenol and isooctane. Of these three, the strain RRKY5 utilized a wide variety of substrates and grew faster than the others. Results of HPLC analysis indicated that 4-t-OP degradation took place both in the presence and absence of the co-substrate dextrose (0.05%): within 24 days, 93% or 95% of 4-t-OP was degraded by C. rugopelliculosa RRKY5 in media with or without dextrose, whereas degradation was lower (less than 75%) in the two strains of G. candidum. Therefore, in contrast to the 4-t-OP degradation by filamentous ligninolytic fungi, dextrose did not appear to exert a significant impact on this process in yeast cultures. It can be concluded that RRKY5 is a potent candidate for the biodegradation of 4-t-OP and thus can potentially be used for bio-remedial actions in the future. To our knowledge, this is the first evidence demonstrating that pure cultures of yeast strains are capable of utilizing branched-chain OP.

Phthalates have been blended in various compositions as plasticizers worldwide for a variety of purposes. Consequently, humans are exposed to a wide spectrum of phthalates that needs to be researched and understood correctly. The goal of this review is to focus on phthalate's internal exposure pathways and possible role of human digestion on liver toxicity. In addition, special focus was made on stem cell therapy in reverting liver toxicity. The known entry of higher molecular weight phthalates is through ingestion while inhalation and dermal pathways are for lower molecular weight phthalates. In human body, certain phthalates are digested through phase 1 (hydrolysis, oxidation) and phase 2 (conjugation) metabolic processes. The phthalates that are made bioavailable through digestion enter the blood stream and reach the liver for further detoxification, and these are excreted via urine and/or feces. Bis(2-ethylhexyl) phthalate (DEHP) is a compound well studied involving human metabolism. Liver plays a pivotal role in humans for detoxification of pollutants. Thus, continuous exposure to phthalates in humans may lead to inhibition of liver detoxifying enzymes and may result in liver dysfunction. The potential of stem cell therapy addressed herewith will revert liver dysfunction and lead to restoration of liver function properly.

In this study, we cultivated from subsurface sediments an anaerobic clostridial consortium that was composed of a fermentative Fe-reducer Clostridium species (designated as strain FGH) and a novel sulfate-reducing bacterium belonging to the clostridia family Vellionellaceae (designated as strain RU4). In pure culture, Clostridium sp. strain FGH mediated the reductive dissolution/transformation of iron oxides during growth on peptone. When Clostridium sp. FGH was grown with strain RU4 on peptone, the rates of iron oxide reduction were significantly higher. Iron reduction by the consortium was mediated by multiple mechanisms, including biotic reduction by Clostridium sp. FGH and biotic/abiotic reactions involving biogenic sulfide formed by strain RU4. The Clostridium sp. FGH produced hydrogen during fermentation, and the presence of hydrogen inhibited growth and iron reduction activity. The sulfate-reducing partner strain RU4 was stimulated by the presence of H2and generated reactive sulfide which promoted ...

This study investigated the potential of methane production of thermophilic anaerobic co-digestion of diluted pulp and paper sludge (DPPS) with diluted pig manure (DPM). The mixture ratios, that is, pulp and paper sludge (PPS) and pig manure (PM) were mixed with tap water to create slurry with a volatile solid (VS) content of 4% as substrate, respectively. The co-digestion was carried out in a 2 liter reactor tank which was stirred semi-continuously with a five phase organic loading rate (OLR) consequently the contents were being drawn-and-fed daily. This experimental design was operated by a triplicate with steady state operations during a thermophilic condition of 50 � C and a constant solid retention time (SRT) of 10 days. The results demonstrated that the co-digestion of DPPS and DPM mixture ratio (50:50) resulted in higher methane production, specific methane yields (SMY), and soluble chemical oxygen demand (SCOD) removal efficiency. The highest methane content of biogas, SMY, volatile solid (VS) degradation rate and SCOD removal efficiency of 5654 ± 421%, 7158 ± 875 ml-CH4/g-VSadded ,5 574 ± 027% and 8354 ± 632%, respectively, were achieved with process stability. However, it added too high mixture ratio of PM to reduce methane yield and SCOD removal efficiency. This study showed that there was a good potential of PPS and PM on thermophilic anaerobic co-digestion for methane production.

4-(1,1,3,3-tetramethylbutane)-phenol (4-tert-OP) is one of the most prevalent endocrine disrupting pollutants. Information about bioremediation of 4-tert-OP remains limited, and no study has been reported on the mechanism of 4-tert-OP degradation by yeasts. The yeast Candida rugopelliculosa RRKY5 was proved to be able to utilize 4-methylphenol, bisphenol A, 4-ethylphenol, 4-tert-butylphenol, 4-tert-OP, 4-tert-nonylphenol, isooctane, and phenol under aerobic conditions. The optimum conditions for 4-tert-OP degradation were 30 °C, pH 5.0, and an initial 4-tert-OP concentration of 30 mg L−1; the maximum biodegradation rate constant was 0.107 d−1, equivalent to a minimum half-life of 9.6 d. Scanning electron microscopy revealed formation of arthroconidia when cells were grown in the presence of 4-tert-OP, whereas the cells remained in the budding form without 4-tert-OP. Identification of the 4-tert-OP degradation metabolites using liquid chromatography–hybrid mass spectrometry revealed three different mechanisms via both branched alkyl side chain and aromatic ring cleavage pathways.