Biodegradation of Di-(2-ethylhexyl) Phthalate by Rhodococcus ruber YC-YT1 in Contaminated Water and Soil.

Ting Yang,Haisheng Wang,Ruth Nahurira,Junhuan Wang,Yanchun Yan,Jiayi Wang,Lei Ren,Shuanghu Fan,Yang Jia

doi:10.3390/ijerph15050964

Abstract

Di-(2-ethylehxyl) phthalate (DEHP) is one of the most broadly representative phthalic acid esters (PAEs) used as a plasticizer in polyvinyl chloride (PVC) production, and is considered to be an endocrine-disrupting chemical. DEHP and its monoester metabolites are responsible for adverse effects on human health. An efficient DEHP-degrading bacterial strain Rhodococcus ruber YC-YT1, with super salt tolerance (0–12% NaCl), is the first DEHP-degrader isolated from marine plastic debris found in coastal saline seawater. Strain YC-YT1 completely degraded 100 mg/L DEHP within three days (pH 7.0, 30 °C). According to high-performance liquid chromatography–mass spectrometry (HPLC-MS) analysis, DEHP was transformed by strain YC-YT1 into phthalate (PA) via mono (2-ethylehxyl) phthalate (MEHP), then PA was used for cell growth. Furthermore, YC-YT1 metabolized initial concentrations of DEHP ranging from 0.5 to 1000 mg/L. Especially, YC-YT1 degraded up to 60% of the 0.5 mg/L initial DEHP concentration. Moreover, compared with previous reports, strain YC-YT1 had the largest substrate spectrum, degrading up to 13 kinds of PAEs as well as diphenyl, p-nitrophenol, PA, benzoic acid, phenol, protocatechuic acid, salicylic acid, catechol, and 1,2,3,3-tetrachlorobenzene. The excellent environmental adaptability of strain YC-YT1 contributed to its ability to adjust its cell surface hydrophobicity (CSH) so that 79.7–95.9% of DEHP-contaminated agricultural soil, river water, coastal sediment, and coastal seawater were remedied. These results demonstrate that R. ruber YC-YT1 has vast potential to bioremediate various DEHP-contaminated environments, especially in saline environments.

Highlights

Phthalic acid esters (PAEs) are a family of refractory organic compounds that are widely used as plasticizers for polyvinyl chloride (PVC) and other polymers to increase flexibility and longevity [1,2].PAEs are used as additives in personal care products and medical devices [3]
A DEHP-degrading bacterium YC-YT1 was isolated from marine plastic debris in coastal seawater by enrichment and domestication
The phylogenetic tree demonstrated that strain YC-YT1 was classified as a Rhodococcus species and had a 99% similarity to Rhodococcus ruber DSM 43338 (GenBank accession number X80625) based on 16S rRNA gene analysis (Figure 2)

Summary

Introduction

Phthalic acid esters (PAEs) are a family of refractory organic compounds that are widely used as plasticizers for polyvinyl chloride (PVC) and other polymers to increase flexibility and longevity [1,2]. PAEs are used as additives in personal care products and medical devices [3]. PAEs leach into the environment, mainly from domestic and industrial effluents, plastic decomposition, and agricultural or urban outflow [4]. PAEs are classified as endocrine-disrupting chemicals (EDCs) due to their xenoestrogenic and endocrine-disrupting characteristics [4,5,6]. Di-(2-ethylhexyl)-phthalate (DEHP) is the most widely-used phthalate, and is listed as a priority hazardous substance by the European Community, the United States Environmental Protection Agency, Int. J. Public Health 2018, 15, 964; doi:10.3390/ijerph15050964 www.mdpi.com/journal/ijerph

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