The weak magnetic field (WMF) enhances the stimulation of polymyxin B sulfate (POL) on Vibrio qinghaiensis sp.-Q67

Ya-Qian Xu,Shu-Shen Liu,Ze-Jun Wang,Kai Li

doi:10.1186/s12302-020-0294-x

Abstract

BackgroundThe weak magnetic field (WMF) can enhance the ability to remove target pollutants in wastewater, which drives us to consider whether WMF could give rise to the hormesis or not. In our previous study, it was found that polymyxin B sulfate (POL) can induce weak hormesis on Vibrio qinghaiensis sp.-Q67 (Q67). To this end, we set up four different WMF treatments during Q67 culture and POL exposure process, having no WMF in all cases (NW), adding WMF all the time (AW), exerting WMF only during the bacterial culture (BW), and exerting WMF only in POL exposure period (EW).ResultsIt was shown that the concentration–response curves (CRCs) of POL in four WMF treatments at the exposure times of 6, 9, and 12 h are non-monotonic hormetic curves where the maximum stimulative effects (Emin) of POL in BW and EW are obviously larger than those in AW and NW. The maximum Emin is 26.8% occurring in EW and 20.7% in BW at 6 h, while the max Emin is 14.6% in NW at 9 h, it means that stimulations of POL in BW and EW are earlier and stronger than those in NW. These findings first indicated that WMF can enhance the hormesis of POL.ConclusionsThis study showed that WMF as a key factor may influence the maximum stimulation effect of hormesis. The characteristic of biphasic (hormetic effect) challenges the traditional classical threshold model that is close to chemical risk assessment. But the mechanism of hormesis even now is inconclusive. WMF as a novelty and neglected factor has the potential to support the further development of hormesis mechanism.

Highlights

The weak magnetic field (WMF) can enhance the ability to remove target pollutants in wastewater, which drives us to consider whether WMF could give rise to the hormesis or not
Concentration–response relationships of polymyxin B sulfate (POL) The concentration-inhibition data of POL in four WMF treatments at different time points can be fitted by the Least square support vector regression (LS-SVR) [53]
Taking the median effective concentrations (EC50) as a toxicity index, apart from the toxicity of POL in four WMF treatments at the first time point (0.25 h) is less, those at the other four time points are almost the same. the cor‐ responding concentration of Emin (ECmin) in all WMF treatments at all time points are around 1.00E−07 mol/L, which implies that both the WMF and exposure time do not alter the minimum inhibitory effective concentration

Summary

Introduction

The weak magnetic field (WMF) can enhance the ability to remove target pollutants in wastewater, which drives us to consider whether WMF could give rise to the hormesis or not. It was found that polymyxin B sulfate (POL) can induce weak hormesis on Vibrio qinghaiensis sp.-Q67 (Q67). To this end, we set up four different WMF treatments during Q67 culture and POL exposure process, having no WMF in all cases (NW), adding WMF all the time (AW), exerting WMF only during the bacterial culture (BW), and exerting WMF only in POL exposure period (EW). It was demonstrated that some chemicals could induce the hormesis in vitro by very low-dose environmental factors such as low-dose-rate gamma rays and X-rays [62, 82]. A growing body of evidence has accumulated on hormetic effects of several chemicals for a number of biological endpoints

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