Physiological and metabolic responses of Limnoperna fortunei to KMnO4 and NaClO exposure

Abstract

Biofouling of Limnoperna fortunei causes increment on water conveyance energy and deteriorates concrete during freshwater transportation process. Apart from application of chemical oxidants such as KMnO₄ and NaClO, few other strategies can control L. fortunei. However, the cellular and metabolic responses of L. fortunei during KMnO₄ and NaClO exposure are still not fully understood. This work aimed to illustrate the physiological and metabolic status of L. fortunei exposed to KMnO₄ and NaClO at concentration of 1, 2, 4, and 8 mg l^-1. The mortality rate, amount of acid and neutral mucous secretions, and the activities of antioxidant enzymes were determined after KMnO₄ and NaClO exposure. The activities of biotransformation and detoxification enzymes, including as superoxide dismutase, catalase, glutathione peroxidase, and acetylcholinesterase, increased in response to NaClO exposure as an adaptive response. In comparison, KMnO₄ exposure showed severer lethal effect, especially at concentrations higher than 4 mg l^-1. The increment of lipid peroxides followed the raise of KMnO₄ concentrations, indicating the toxic effect from KMnO₄. The results of liquid chromatography-mass spectrometry (LC-MS)-based metabolomic revealed that KMnO₄ mainly affected the purine and energy metabolism pathway and disrupted osmoregulatory processes, whereas NaClO mainly affected amino acid metabolism. These findings provided insight on controlling the biofouling of L. fortunei. PRACTITIONER POINTS: KMnO₄ was effective to inactivate L. fortunei rather than NaClO. Antioxidant system of L. fortunei was valid to counteract the oxidative stress from NaClO exposure, while paralyzation during KMnO₄ exposure. Amino acid metabolism was involved in polishing immune responses and detoxification during NaClO exposure. Disordered purine and energy metabolism pathway and disrupted osmoregulatory processes were induced by KMnO₄. Mitigating L. fortunei biofouling reduces raw water energy demands and concrete degradation risks.

Keywords: LC–MS‐based metabolomics; Limnoperna fortunei; enzymatic activities; freshwater transportation system; oxidant stress.