The widespread application of metal-based nanoparticles (MNPs) has prompted great interest in nano-biosafety. Consequently, as more and more MNPs are released into the environment and eventually sink into the soil, plants, as an essential component of the ecosystem, are at greater risk of exposure and response to these MNPs. Therefore, to understand the potential impact of nanoparticles on the environment, their effects should be thoroughly investigated. Arabidopsis (Arabidopsis thaliana L.) is an ideal model plant for studying the impact of environmental stress on plants’ growth and development because the ways in which Arabidopsis adapt to these stresses resemble those of many plants, and therefore, conclusions obtained from these scientific studies have often been used as the universal reference for other plants. This study reviewed the main findings of present-day interactions between MNPs and Arabidopsis thaliana from plant internalization to phytotoxic effects to reveal the mechanisms by which nanomaterials affect plant growth and development. We also analyzed the remaining unsolved problems in this field and provide a perspective for future research directions.

2,4,6-Trinitrotoluene (TNT) is an aromatic pollutant that is difficult to be degraded in the natural environment. The screening of efficient degrading bacteria for bioremediation of TNT has received much attention from scholars. In this paper, transcriptome analysis of the efficient degrading bacterium Buttiauxella sp. S19-1 revealed that the monooxygenase gene (BuMO) was significantly up-regulated during TNT degradation. S-ΔMO (absence of BuMO gene in S19-1 mutant) degraded TNT 1.66-fold less efficiently than strain S19-1 (from 71.2% to 42.9%), and E-MO mutant (Escherichia coli BuMO-expressing strain) increased the efficiency of TNT degradation 1.33-fold (from 52.1% to 69.5%) for 9 h at 180 rpm at 27 °C in LB medium with 1.4 µg·mL−1 TNT. We predicted the structure of BuMO and purified recombinant BuMO (rBuMO). Its specific activity was 1.81 µmol·min−1·mg−1 protein at pH 7.5 and 35 °C. The results of gas chromatography mass spectrometry (GC–MS) analysis indicated that 4-amino-2,6-dinitrotoluene (ADNT) is a metabolite of TNT biodegradation. We speculate that MO is involved in catalysis in the bacterial degradation pathway of TNT in TNT-polluted environment.

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