Decabromodiphenyl ethane (DBDPE) can pose a potential toxic threat to human beings and the environment. P. ostreatus , as one of the typical white-rot fungi, can effectively degrade various refractory pollutants. The biodegradable characteristics of DBDPE by P. ostreatus , as well as the mechanisms, and toxicological response were investigated in this study. The removal rate reached 47.73% and 43.20%, respectively, for 5 and 20 mg/L DBDPE after 120-h degradation by P. ostreatus . As a coexisting substance, Pb could inhibit the biodegradation. It is found that both the intracellular enzyme (P450) and extracellular enzymes (manganese peroxidase (MnP), lignin peroxidase (LiP), and laccase (Lac)) played a very important role in the biodegradation of DBDPE, of which Lac dominated the degradation. The toxic response was monitored during the degradation. The activities of SOD and CAT were enhanced to eliminate excess ROS in P. ostreatus triggered by DBDPE. In addition, debromination, hydroxylation, and oxidation were inferred as the main degradation pathways preliminarily. The findings provide a theoretical basis for the application of microbial degradation of DBDPE contamination.
With the continuous increase of e-waste, more and more pollutants such as tetrabromobisphenol A (TBBPA) and bivalent cadmium ions (Cd(Ⅱ)) are often detected in the surface water. However, their combined toxicity to microalgae is still unclear. Therefore, this study comprehensively explored effects of TBBPA and Cd(Ⅱ) on freshwater microalgae Chlorella sorokiniana , in terms of growth, photosynthetic activity, biochemical characteristics and molecular level. Results showed that Cd(Ⅱ) below 1 mg/L could promote the growth of microalgae, while TBBPA with various dosages showed inhibitory effects. The coexistence of TBBPA and Cd(Ⅱ) had a significant effect on photosynthetic activity, enzyme activity and chlorophylls content. Simultaneously, the release of dissolved organic matters reduced the damage of pollutants to algae. Moreover, C. sorokiniana had a good removal effect on Cd(Ⅱ), and the removal efficiency could reach 72.83%. Interestingly, addition of Cd(Ⅱ) could enhance the removal effect of C. sorokiniana on TBBPA, and the highest removal reached 44.16%. Transcriptome analysis showed that C. sorokiniana had different responses to Cd(Ⅱ) and TBBPA stress, while both caused the regulation of protein synthesis-related genes. Additionally, exposure to Cd(II) upregulated DNA replication-related genes in microalgae, thereby promoting cell proliferation. This study provides insights into toxic mechanisms of TBBPA and Cd(Ⅱ) to microalgae together with their removal patterns, which offers a theoretical basis for further assessment of the actual risk of Cd(II) and TBBPA to aquatic organisms.
The biomolecular responses of bacteria to 2D nanosheets that result from nano–bio interfacial interactions remain to be thoroughly examined. Herein, Fourier transform infrared (FTIR) multivariate and 2D correlation analyses were performed to assess the composition and conformational changes in bacterial biomacromolecules (lipids, polysaccharides, and carbohydrates) upon exposure to Ti3C2Tx nanosheets. General toxicity assays, 3D excitation–emission matrix fluorescence analyses, extended Derjaguin–Landau–Verwey–Overbeek theory interaction calculations, and isothermal titration calorimetry were also performed. Our results demonstrate that Ti3C2Tx nanosheets considerably impact Gram-positive bacteria (Bacillus subtilis), causing oxidative damage and inactivation by preferentially interacting with and disrupting the cell walls. The bilayer membrane structure of Gram-negative bacteria (Escherichia coli) endows them with increased resistance to Ti3C2Tx nanosheets. The unmodified nanosheets had a higher affinity to bacterial protein components with lower toxicity due to their susceptibility to oxidation. Surface modification with KOH or hydrazine (HMH), particularly HMH, induced stronger dispersion, antioxidation, and affinity to bacterial phospholipids, which resulted in severe cell membrane lipid peroxidation and bacterial inactivation. These findings provide valuable insight into nano–bio interfacial interactions, which can facilitate the development of antimicrobial and antifouling surfaces and contribute to the evaluation of the environmental risks of nanomaterials.
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