Introduction: Bioremediation has been shown to be an effective strategy for removing toxic pollutants from the environment, particularly organic chemicals such as petroleum hydrocarbons. This paper investigates the changes in toxicity of petroleum-contaminated soil as a result of microbial remediation processes.Methods: Changes in the ecotoxicity of the contaminated soil were examined using a plant, earthworm, enzyme activity and luminescent bacteria toxicity tests.Results: The results showed that bioremediation could effectively degrade petroleum hydrocarbon (C₁₀–C₄₀) pollutants. After 42 days of remediation, the petroleum hydrocarbon (C₁₀–C₄₀) content of Group A (bioaugmented polluted wetland soil) decreased from 1.66 g/kg to 1.00 g/kg, and the degradation rate was 40.6%. The petroleum hydrocarbon (C₁₀–C₄₀) content of Group B (bioaugmented polluted farmland soil decreased from 4.00 g/kg to 1.94 g/kg, and the degradation rate was 51.6%. During the microbial remediation progress, the ecological toxicity of petroleum-contaminated soil first increased and then decreased. The photosynthetic pigment content index in the higher plant toxicity test, the earthworm survival index and the soil catalase activity all showed good agreement with the relative luminescence index of extracted DCM/DMSO in the luminescent bacterial toxicity test. The soil toxicity decreased significantly after remediation. Specifically, the photosynthetic pigment content of wheat were inhibited in the soil during the whole process (remediation for 42 days), and decreased to the minimum on remediation day 21. The 7-day and 14-day survival rate of earthworms in Group A and Group B gradually decreased in the soil remediation process, and then gradually increased, survival rate at the end of remediation was higher than at the beginning. Soil catalase activity was significantly negatively correlated with petroleum hydrocarbon (C₁₀–C₄₀) content (−0.988, −0.989). The ecological toxicity of contaminated soil reached to the maximum on the 21st day of remediation, relative luminosity of luminescent bacteria in dichloromethane/dimethyl sulfoxide extracts from Group A and Group B were 26.3% and 16.3%, respectively.Conclusion: Bioremediation could effectively degrade petroleum hydrocarbon (C₁₀–C₄₀) pollutants. Wheat photosynthetic pigment content, earthworm survival rate, soil catalase activity and relative luminescence of luminescent bacteria can better indicate the ecological toxicity of petroleum-contaminated soil in bioremediation process.

We reported a green and simple Cu-catalyzed method for the efficient synthesis of 2-chloro-7-cyclopentyl-N,N-dimethyl-7H-pyrrolo[2,3-d]pyrimidine-6-carboxamide as the key intermediate in the synthetic approaches to pyrrolo[2,3-d]pyrimidine derivatives from 5-bromo-2,4-dichloropyrimidine through two routes in four steps and five steps, respectively. This method provided green and economical approaches toward numerous pyrrolo[2,3-d]pyrimidine derivatives. GRAPHICAL ABSTRACT

Background/Objectives: Petroleum contamination in soil exerts toxic effects on earthworms (Eisenia fetida) through non-polar narcotic mechanisms. However, the specific toxicities of individual petroleum components remain insufficiently understood. Methods: This study investigates the effects of four petroleum components—saturated hydrocarbons, aromatic hydrocarbons, resins, and asphaltenes—on earthworms in artificially contaminated soil, utilizing a combination of biochemical biomarker analysis and metabolomics to uncover the underlying molecular mechanisms. Results: The results revealed that aromatic hydrocarbons are the most toxic fraction, with EC50 concentrations significantly lower than those of other petroleum fractions. All tested fractions triggered notable metabolic disturbances and immune responses in earthworms after 7 days of exposure, as evidenced by significant changes in metabolite abundance within critical pathways such as arginine synthesis, a-linolenic acid metabolism, and the pentose phosphate pathway. According to the KEGG pathway analysis, saturated hydrocarbon fractions induced marked changes in glycerophospholipid metabolism, and arginine and proline metabolism pathways, contributing to the stabilization of the protein structure and membrane integrity. Aromatic hydrocarbon fractions disrupted the arachidonic acid metabolic pathway, leading to increased myotube production and enhanced immune defense mechanisms. The TCA cycle and riboflavin metabolic pathway were significantly altered during exposure to the colloidal fraction, affecting energy production and cellular respiration. The asphaltene fraction significantly impacted glycolysis, accelerating energy cycling to meet stress-induced increases in energy demands. Conclusions: Aromatic hydrocarbons accounted for the highest level of toxicity among the four components in petroleum-contaminated soils. However, the contributions of other fractions to overall toxicity should not be ignored, as each fraction uniquely affects key metabolic pathways and biological functions. These findings emphasize the importance of monitoring metabolic perturbations caused by petroleum components in non-target organisms such as earthworms. They also reveal the specificity of the toxic metabolic effects of different petroleum components on earthworms.

(1) Background: Polycyclic aromatic hydrocarbons (PAHs) are important components of petroleum and pose a serious threat to the soil environment of oil production well sites. Therefore, scientific risk thresholds and ecological risk assessment methods must be established for PAHs in petroleum-contaminated soils. (2) Methods: In this study, based on the environmental DNA (eDNA) method, the soil bacterial community was considered as a receptor to assess the ecological risks of PAH contamination in aged petroleum-polluted soils. A combination of the risk quotient and the equivalent toxicity factor was used to assess the ecological risk of PAHs. (3) Results: A dose–response curve was plotted to determine the 50% effective concentration (EC₅₀) of the total equivalent toxicity for 16 PAHs (∑TEQ_BaP) in petroleum-contaminated soils. Following the plot of the species sensitivity distribution (SSD) curve, the hazardous concentration for protecting 95% species values (HC₅) of petroleum hydrocarbons (TPHs), electrical conductivity (EC), and total equivalent toxicity of PAHs were calculated to be 892.1 μs·cm⁻¹, 149.9 mg·kg⁻¹, and 0.2601 mg·kg⁻¹, respectively. The regression models of the distribution factor (DF) and aging factor (AF) were defined as DF = −1.132 SOM + 0.033PAHs + 9.968 and AF = 242.518 SOM + 1256.029 lgpH + 0.024 EC − 1415.447. Following calibrations of the DF and AF, the value of HC₅ was determined as 0.1956 mg·kg⁻¹, which could be considered the risk threshold of the total toxicity of PAHs. The calibrated toxicity data distribution was consistent with that of the normal cumulative probability distribution model. The results showed that 50% of the aged petroleum-contaminated soils showed high-risk levels of bacterial communities exposed to PAHs. (4) Conclusions: This study provides a reference for deriving the ecological risk threshold of soil pollutants and explores alternative methods for the ecological risk assessment of PAHs at specific sites.

Bioremediation is a low-cost, eco-friendly technique to reduce and/or eliminate pollutants from environment. Moreover, effective biological degrader for contaminants removal is important during bioremediation process. Here, the strain RHZ01, isolated from petroleum-contaminated soil in Shengli Oilfield, was identified as Rhodococcus qingshengii by the morphology, physiology, biochemistry and molecular biology. Strain RHZ01 was able to use diesel as the sole carbon source. The optimal initial pH and temperature for strain RHZ01 growth and diesel degradation were 6-8.5 and 20-30ºC, respectively. Nutrients (NaNO3, NH4Cl, KNO3 and Urea) could replace NH4NO3. And Mg2+ was required for strain RHZ01 growth and diesel degradation. To investigate the diesel degrading mechanisms of this strain, the complete genome was sequenced and annotated. The complete genome consists of one chromosome with a total length 6,506,318 bp and a G+C content of 62.48%. Five putative alkane monooxygenases (AlkB) encoding genes were further analyzed, and their protein sequences were characterized and compared with other published AlkBs in Rhodococcus spp.. The physicochemical features of the five AlkBs were analyzed, and these monooxygenase proteins are alkaline, unstable and thermostable. AlkB1, AlkB2 and AlkB3 are hydrophilic protein while the other proteins were hydrophobic. All of these alkane monooxygenases share several conserved regions, such as HYG-motif and three Hist boxes. From the results, it is demonstrated that bacterial strain isolated from petroleum-contaminated could be the potential bioremediation agent for diesel removal.