More and more evidences about the toxic effects of 4,4'-Isopropylidenediphenol (BPA) were reported (Bernardo et al. 2021, Tišler et al. 2016). In order to meet the restrictions and regulations, manufacturers are gradually using 4,4'-sulfonyl-diphenol (BPS) instead of BPA as a substitute for industrial applications(Cai &Zhang 2022). However, studies have shown that BPS also possesses geno-toxicity and estrogenic activity similar to that of BPA (Chen et al. 2002, Grignard et al. 2012). Another study from Japan suggests that BPS appears to be more resistant to environmental degradation than BPA (Ike et al. 2006, Silva et al. 2012), which made it more hazardous. In addition, the occurrence of BPS in all types of environmental matrices was reported (Viñas et al. 2010). For example, BPS in sewage sludge was up to 523 mg/kg dw (Lee et al. 2015, Song et al. 2014), which resulted in the release of BPS into rivers due to improper processing, from where even into groundwater, drinking water, and soil, adversely affecting environmental ecosystems and human health (Garcia-Rodríguez et al. 2014, Wang et al. 2015).
Many articles reported various methods for the removal of BPS, including advanced oxidation (Repousi et al. 2017), adsorption (Banihashemi &Droste 2014), flocculation and biological degradation (Fudala-Ksiazek et al. 2018, Liu et al. 2016, Sasaki et al. 2005). However, these methods also showed shortcomings such as high cost, secondary pollution, time-consuming and so on. Among these ways, biological degradation is a better alternative. However, current wastewater treatment plants aim to remove phosphorus, nitrogen and bio-degradable organic matter through the metabolic activity of a variety of microbial communities (Krah et al. 2016, Reis et al. 2017), but exhibits low efficiency and long lag time to the organics micro-pollutants (e.g. BPS). On the other hand, sewage sludge contains many kinds of enzymes (including intracellular and extracellular enzymes) which can degrade micropollutants at high efficiency (Braun et al. 2011, Villemur et al. 2013). Endophytic bacteria from rhizomes and roots of reed plants were widely used for micropollutant degradation and bioremediation, owing to their extracellular enzymes which serve either a protective function and oxidise extracellular toxic soluble phenolic metabolites to insoluble polymerized products, or a degradative function and oxidise polymeric lignin or phenols for metabolic purposes (Harvey et al. 2002, He et al. 2017, Sauvêtre et al. 2018). Daniel Krah et al. used native extracellular enzymes extracted from waste sludge to remove pharmaceuticals, biocides and personal care products (Krah et al. 2016), but the relative removal mechanism was not clarified enough. Intracellular enzymes could also inevitably show a high metabolic versatility in the degradation of micro-contaminants (Fischer &Majewsky 2014, Sasaki et al. 2005). However, few reports focus on the removal of bisphenol chemicals (e.g. BPS) from aqueous solution with the intracellular and extracellular enzymes extracted from sludge and reed sediment. It has been reported that the use of multi-enzyme complexes can significantly promote the overall degradation efficiency of substrates(Huang et al. 2019). Thus, it is meaningful to study the BPS removal with multi-enzymes and the interaction mechanism. In addition, physiological structure of the multi-enzymes affects its lifetime, which is a key factor the utilization of enzymes (Odnell et al. 2016). While several studies showed that BPS not only could induce DNA damage(Grelska &Noszczynska 2020), but also irreversibly bind serum albumin, pepsin, trypsin and α-amylase, resulting in the change of physiological structure and function the enzymes and an increased risk of metabolic syndrome (Rezg et al. 2019, Usman &Ahmad 2016, Yang et al. 2016). Therefore, it is necessary to explore the change of physiological structure and function of multi-enzymes induced by BPS in the process of BPS removal.
The aims of this study are to (i) provide a new method for BPS removal in aqueous solution with the multi-enzymes from waste sludge and reveal the removal mechanism, (ii) to clarify the effect of the structure and function of the multi-enzymes on BPS removal.