Alleviative effects of a novel strain Bacillus coagulans XY2 on copper-induced toxicity in zebrafish larvae

Copper (Cu) is a kind of micronutrient element that is essential for human metabolism. However, it is also considered as an environmental pollutant which is toxic to organisms at a high concentration level. Probiotics, regarded as beneficial microorganisms for promoting human health, have functions of antioxidant capacity, immune-enhancing properties, in-testinal barrier protection and regulation. Several studies have reported that probiotics show positive effects on alleviating and intervening heavy metals toxicity. However, evidence for relieving copper-induced toxicity by probiotics is still limited. In this study, we firstly con-ducted a zebrafish larvae model to screen out microorganisms which are helpful for CuSO4 toxicity resistance and one novel stran named as Bacillus coagulans XY2 was discovered with the best protective activity. B. coagulans XY2 significantly reduced the mortality of zebrafish larvae exposed to 10 mu mol/L CuSO4 for 96 hr, as well as alleviated the neutrophils infiltra-tion in the larvae lateral line under a 2 hr exposure. B. coagulans XY2 exhibited a high in vitro antioxidant activity and against CuSO4-induced oxidative stress in zebrafish larvae by up-regulating sod1, gstp1 and cat gene transcriptional levels and relevant enzymatic activi-ties. CuSO4 stimulated the inflammation process resulting in obvious increases of gene il-1 beta and il-10 transcription, which were suppressed by B. coagulans XY2 intervention. Overall, our results underline the bio-function of B. coagulans XY2 on protecting zebrafish larvae from copper toxicity, suggesting the potential application values of probiotics in copper toxicity alleviation on human and the environment. (c) 2022 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.

Automated summary

This study identified a probiotic strain called Bacillus coagulans XY2 that showed protective effects against copper toxicity. It exhibited high antioxidant activity and suppressed the inflammation process, thus alleviating oxidative stress and reducing mortality in zebrafish larvae exposed to copper.