The role of lignin in 17β-estradiol biodegradation: insights from cellular characteristics and lipidomics

Abstract

17β-estradiol (E2) is an endocrine disruptor, and even trace concentrations (ng/L) of environmental estrogen can interfere with the endocrine system of organisms. Lignin holds promise in enhancing the microbial degradation E2. However, the mechanisms by which lignin facilitates this process remain unclear, which is crucial for understanding complex environmental biodegradation in nature. In this study, we conducted a comprehensive analysis using cellular and lipidomics approaches to investigate the relationship between E2-degrading strain, Rhodococcus sp. RCBS9, and lignin. Our findings demonstrate that lignin significantly enhances E2 degradation efficiency, reaching 94.28% within 5 days with the addition of 0.25 mM lignin. This enhancement is associated with increased microbial growth and activity, reduced of membrane damages, and alleviation of oxidative stress. Fourier Transform Infrared Spectroscopy (FTIR) results indicate that lignin addition alters lipid peaks. Consequently, by analyzing lipid metabolism changes, we further elucidate how lignin addition promotes E2 degradation.

Keywords: 17β-estradiol; Biodegradation; Cells characteristics; Lignin; Lipidomics; Mechanisms of lipid action.

Fig. 1

Effect of different Lignin concentration (25 ℃,1% inoculum amount,30 mg/L E2). A Impact on E2 biodegradation and B Influence on cell growth

Fig. 2

The effect of lignin on the tolerance to salinity and pH. A The impact of different salinity levels (0 g/L,5 mg/L,10 g/L,20 g/L,40 g/L) on lignin tolerance, B The impact of different pH levels on lignin tolerance

Fig. 3

Cell surface changes. A FTIR characteristics of FTIR of Rhodococcus sp.RCBS9 cells cultured in MSM, B SEM images of Rhodococcus sp. RCBS9 in 30 mg/L E2, C SEM images of Rhodococcus sp. RCBS9 in 30 mg/L E2 and 0.25mM lignin (the red circle represents regions of interest and highlights)

Fig. 4

Cellular oxidative stress indices. A SOD activity, B CAT activity, C MDA levels, and D ATP levels

Fig. 5

Cell membrane permeability and hydrophobicity. A Crystal violet uptake of Rhodococcus sp.RCBS9 treated with control (30 mg/L E2) and experimental group (0.25mM Lignin and 30 mg/L E2), B Rhodococcus sp.RCBS9 membrane hydrophobicity. All the values are averages of three replicates from three independent experiments

Fig. 6

Comparative analysis of lipids with/without lignin addition. A Correlation heatmap (POS represents positive ion direction detection, NEG represents negative ion direction detection), B Screening results of differential lipid compounds (VIP > 1.0, FC > 1.5 ), C Volcano diagram of differential lipid compounds, D Matchstick plots illustrating the upregulation and downregulation of lipid compounds with significant fold changes