Weak interaction-alleviated toxicity of aromatic compounds in EPS matrices: Quantifying the noncovalent bonding-to-EPS ecoservice chain

• Published in: Journal of hazardous materials 2021-08, Vol.416, p.125824-125824, Article 125824
• Main Authors: Chen, Kai, Wang, Qian, Fu, Yaojia, Yu, Xiaoxiao, Liu, Peilin, Kang, Fuxing
• Format: Article
• Language: English
• Subjects: Aromatic compound; Ecotoxicity; Extracellular polymeric substance; Noncovalent bonding
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2021.125824

Extracellular polymeric substances (EPSs) constitute a largely global carbon pool that could participate in geochemical process of organic chemicals. Besides the chemical hydrolysis and redox of chemicals exerted by the EPS, weakly noncovalent interactions with dispersive EPS control the toxicity of numerous organic compounds. Nevertheless, there has been a lack of in-depth research on this issue. This work quantified a chain of links from bonding to detoxification using natural biofilms to explore the control behavior of fragile noncovalent bonding to the ecotoxicity of aromatic compounds. Such bonding decreases cell absorbability of m-phenylenediamine, 2-naphthol, and phenanthrene by 5.3–53.6%, resultantly increasing the indices of microbial diversity by 122.2–279.5%. Herein, the 60 kDa chaperonin in EPS acts as the most important contributor (16.4% of the top 20 proteins) to noncovalent interactions. Hydrophilic carboxyl groups in EPS bind with hydroxyl and amino groups of m-phenylenediamine and 2-naphthol via H-bonds, respectively. Methylene and carboxyl groups combine with hydrophobic phenanthrene via CH···π and H-bonding, respectively. A quantified chain was consequently established that weak interaction linearly controls ecotoxicity of aromatic compounds via the above suppressive cell absorbability of aromatic compounds (R2 =0.82). Considering ubiquitous EPS and prevailing aromatic compounds, our findings revealed a previously unnoticed phenomenon in which seemingly fragile noncovalent bonding profoundly alleviates the ecotoxicity of aromatic compounds in Earth’s surface system. [Display omitted] •We quantified a relation chain that is well known but not well studied in biofilms.•Seemingly fragile noncovalent bonding alleviates the ecotoxicity of aromatic compounds.•Hydrophilic functionalities in aromatic compounds bind with carboxyl groups via H-bonds.•PAHs combine with methylene and carboxyl via H-bonding and hydrophobic CH···π interaction.