Benefits from hazards, benefits from nothing, and benefits from benefits: the combined effects of five quaternary ammonium compounds to Vibrio qinghaiensis Q67

Ling-Yun Mo,Yong-An Liu,Jie Zhu,Hong-Hu Zeng,Yan-Peng Liang,Li-Tang Qin

doi:10.1186/s12302-020-00310-z

Abstract

BackgroundCo-exposure of multiple quaternary ammonium compounds (QACs) is widely present in the aquatic environment. The knowledge about their toxicities to microorganism at low concentration is lacking. This study aims to test the toxic response of Vibrio qinghaiensis Q67 (12-h exposure) to individual and mixtures of QACs by the long-term microplate toxicity analysis method (L-MTA).ResultsHormetic effects were observed for five individual QACs at 12-h exposure of Vibrio qinghaiensis Q67. The maximum stimulation effect of − 339.66% was present in the 0.00561 mol/L tetraethylammonium bromide solution. A stimulation effect (− 23.55%) was detected when each of QACs in the five-component mixture was present at 50% effect concentration (“benefits from hazards”). In addition, significant stimulation effects (− 96.28%) were observed for five QACs combined at the zero-effect point concentration (“benefits from nothing”). Further, a significant stimulation effect (− 406.16%) was observed when each of QACs was co-exposed at its maximum stimulation effect concentration. This phenomenon was termed “benefits from benefits”.ConclusionsThe results suggest that both single and mixture of QACs presented hormetic effects. Benefits from hazards, benefits from nothing, and benefits from benefits were observed for the QACs mixtures.

Highlights

Co-exposure of multiple quaternary ammonium compounds (QACs) is widely present in the aquatic environment
The hormetic effects of individual QACs All concentration–response relationships of benzalkonium bromide (BLB), tetraethylammonium bromide (TLB), Benzyltriethylammonium chloride (BLC), CTE, and dodecyl trimethyl ammonium chloride III (DTC) exposed on Vibrio qinghaiensis sp. Q67 (Q67) (12 h) exhibited hormetic effects, i.e., non-monotonic J-type concentration–response curves (CRC)
The possible mechanism of these hormetic effects may be explained by the low concentration of QACs that can play the role of luciferase activator, while high concentration of QACs starts to play the role of luciferase inhibitor by preventing substrate from entering luciferase active center, which is a possible mechanism of QACs’ hormetic effect on luciferase

Summary

Introduction

Co-exposure of multiple quaternary ammonium compounds (QACs) is widely present in the aquatic environment. The knowledge about their toxicities to microorganism at low concentration is lacking. Under long-term exposure conditions, low-dose pollutants may exhibit the so-called hormetic effect [1,2,3,4,5,6]. This phenomenon implies that high-concentration chemicals show an inhibition effect on organisms, while low-concentration. This effect of QACs mixtures was observed at cellular levels [20, 21], so the hormetic effect of QACs should be considered for environmental protection

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