Diatoms are photosynthetic organisms with potential biotechnological applications in the bioremediation sector, having shown the capacity to reduce environmental concentrations of different pollutants. The diatom Cylindrotheca closterium is known to degrade di-n-butyl phthalate (DBP), one of the most abundant phthalate esters in aquatic environments and a known endocrine-disrupting chemical. In this study, we present for the first time the in silico identification of two putative DBP hydrolases (provisionally called DBPH1 and DBPH2) in the transcriptome of C. closterium. We modeled the structure of both DBPH1-2 and their proposed interactions with the substrate to gain insights into their mechanism of action. Finally, we analyzed the expression levels of the two putative hydrolases upon exposure of C. closterium to different concentrations of DBP (5 and 10 mg/l) for 24 and 48 h. The data showed a DBP concentration-dependent increase in expression levels of both dbph1 and 2 genes, further highlighting their potential involvement in phthalates degradation. This is the first identification of phthalate-degrading enzymes in microalgae, providing new insights into the possible use of diatoms in bioremediation strategies targeting phthalates.
Phthalate esters (PAEs) are harmful to human health and have been repeatedly identified in Baijiu samples. In our study, the distribution and degradation characteristics of 14 PAEs in Baijiu raw materials (BRMs) and Baijiu during distillation were detected using QuEChERS or vortex-assisted surfactant-enhanced-emulsification liquid-liquid micro-extraction (VSLLME) methods coupled with gas chromatography-mass spectrometry. The same five PAEs were detected in all tested samples, values ranged from 0.003 to 0.292 mg/kg; however, higher concentrations existed in BRMs compared to Baijiu samples. Using multivariate statistical analysis, detailed distinctions between different varieties of Baijiu and BRMs and separation-related PAE markers were revealed. PAEs concentration during Baijiu distillation showed a decreasing trend. The highest concentrations detected in distillate heads, were 1.6-, 2.3-, and 8.1-fold higher than those in heart1, heart2, and tail distillates, respectively. These findings revealed that PAEs may migrate from BRMs; moreover, that PAEs content can be regulated by distillation.
