Emerging investigator series: dual role of organic matter in the anaerobic degradation of triclosan

Plastic additives as a new threat to the global environment: Research status, remediation strategies and perspectives

Discharge or leaching of plastic additives, which are an essential part of the plastic production process, can lead to environmental pollution with serious impacts on human and ecosystem health. Recently, the emission of plastic additives is increasing dramatically, but its pollution condition has not received enough attention. Meanwhile, the effective treatment strategy of plastic additive pollution is lack of systematic introduction. Therefore, it is crucial to analyze the harm and pollution status of plastic additives and explore effective pollution control strategies. This paper reviews the latest research progress on additives in plastics, describes the effects of their migration into packaged products and leaching into the environment, presents the hazards of four major classes of plastic additives (i.e., plasticizers, flame retardants, stabilizers, and antimicrobials), summarizes the existing abiotic/biotic strategies for accelerated the remediation of additives, and finally provides perspectives on future research on the removal of plastic additives. To the best of our knowledge, this is the first review that systematically analyzes strategies for the treatment of plastic additives. The study of these strategies could (i) provide feasible, cost-effective abiotic method for the removal of plastic additives, (ii) further enrich the current knowledge on plastic additive bioremediation, and (iii) present application and future development of plants, invertebrates and machine learning in plastic additive remediation.

Modeling and optimization of triclosan biodegradation by the newly isolated Bacillus sp. DL4: kinetics and pathway speculation

Triclosan is a widely used antibacterial agent and disinfectant, and its overuse endangered ecological safety and human health. Therefore, reducing residual TCS concentrations in the environment is an urgent issue. Bacillus sp. DL4, an aerobic bacterium with TCS biodegradability, was isolated from pharmaceutical wastewater samples. Response surface methodology (RSM) and artificial neural network (ANN) were carried out to optimize and verify the different condition variables, and the optimal growth conditions of strain DL4 were obtained (35 °C, initial pH 7.31, and 5% v/v). After 48 h of cultivation under the optimal conditions, the removal efficiency of strain DL4 on TCS was 95.89 ± 0.68%, which was consistent with the predicted values from RSM and ANN models. In addition, higher R2 value and lower MSE and ADD values indicated that the ANN model had a stronger predictive capability than the RSM model. Whole genome sequencing results showed that many functional genes were annotated in metabolic pathways related to TCS degradation (e.g., amino acid metabolism, xenobiotics biodegradation and metabolism, carbohydrate metabolism). Main intermediate metabolites were identified during the biodegradation process by liquid chromatography-mass spectrometry (LC-MS), and a possible pathway was hypothesized based on the metabolites. Overall, this study provides a theoretical foundation for the characterization and mechanism of TCS biodegradation in the environment by Bacillus sp. DL4.

Triclosan and related compounds in the environment: Recent updates on sources, fates, distribution, analytical extraction, analysis, and removal techniques

Triclosan (TCS) has been widely used in daily life because of its broad-spectrum antibacterial activities. The residue of TCS and related compounds in the environment is one of the critical environmental safety problems, and the pandemic of COVID-19 aggravates the accumulation of TCS and related compounds in the environment. Therefore, detecting TCS and related compound residues in the environment is of great significance to human health and environmental safety. The distribution of TCS and related compounds are slightly different worldwide, and the removal methods also have advantages and disadvantages. This paper summarized the research progress on the source, distribution, degradation, analytical extraction, detection, and removal techniques of TCS and related compounds in different environmental samples. The commonly used analytical extraction methods for TCS and related compounds include solid-phase extraction, liquid-liquid extraction, solid-phase microextraction, liquid-phase microextraction, and so on. The determination methods include liquid chromatography coupled with different detectors, gas chromatography and related methods, sensors, electrochemical method, capillary electrophoresis. The removal techniques in various environmental samples mainly include biodegradation, advanced oxidation, and adsorption methods. Besides, both the pros and cons of different techniques have been compared and summarized, and the development and prospect of each technique have been given.

Degradation of Triclosan in the Water Environment by Microorganisms: A Review

Triclosan (TCS), a kind of pharmaceuticals and personal care products (PPCPs), is widely used and has had a large production over years. It is an emerging pollutant in the water environment that has attracted global attention due to its toxic effects on organisms and aquatic ecosystems, and its concentrations in the water environment are expected to increase since the COVID-19 pandemic outbreak. Some researchers found that microbial degradation of TCS is an environmentally sustainable technique that results in the mineralization of large amounts of organic pollutants without toxic by-products. In this review, we focus on the fate of TCS in the water environment, the diversity of TCS-degrading microorganisms, biodegradation pathways and molecular mechanisms, in order to provide a reference for the efficient degradation of TCS and other PPCPs by microorganisms.

Effects of triclosan on performance, microbial community and antibiotic resistance genes during partial denitrification in a sequencing moving bed biofilm reactor

Effects of triclosan (TCS) on performance, microbial community and antibiotic resistance genes (ARGs) during partial denitrification (PD) were investigated in a sequencing moving bed biofilm reactor (SMBBR). TCS inhibited nitrite accumulation; inhibition effect was more obvious as TCS concentration increased from 1 to 5 mg/L, but it could recover. Extracellular polymeric substances contents increased with 1 mg/L TCS addition and decreased a lot at 5 mg/L TCS. Community structure in biofilm was different from that in floccular sludge, but it was similar at 5 mg/L TCS. Illumina sequencing showed that Pseudomonas, Aeromonas, Shewanella and Thauera became dominant genera. Abundance of nirS was stable and higher than that of narG and nosZ. High-throughput qPCR showed that mexF, acrA-02, fabK, etc. were screened at 5 mg/L TCS. IntI1 and tnpA-04 were abundant mobile genetic elements. The study furthers understanding of effects of TCS on PD, bacterial communities and ARGs in SMBBR.