Metabolomics analysis of shiitake Lentinan to alleviate sodium bicarbonate-induced renal injury in Carassius auratus and its effect on gut microbial community

Salinity stress is a significant hazard to aquatic creatures' survival and growth. Lentinan (LNT) is an active chemical obtained from the seeds of high-quality shiitake mushrooms with pharmacological effects including antioxidant, anti-inflammatory, anti-tumor, anti-virus, and immune system modulation. However, the physiological control of LNT on carbonate alkalinity stress in Carassius auratus , as well as the metabolites formed in response to endogenous chemicals, remain unclear. In this study, we investigated the mitigating effect of mushroom polysaccharides on NaHCO 3 -induced kidney injury in Carassius auratus by observing the effect of LNT on the kidney tissues of Carassius auratu s, detecting apoptosis of kidney tissues, and analyzing the changes in the metabolism of kidney tissues of Carassius auratus by using non-targeted metabolomics methods. Study findings revealed that adding LNT greatly increased the growth performance of Carassius auratus , relieved the inhibitory impact of NaHCO 3 on Carassius auratus growth, and decreased kidney tissue cell apoptosis. 175 differential metabolites were identified in the NaHCO 3 group (GP group), of which 105 were up-regulated and 75 were down-regulated. The levels of the hazardous metabolites 15-OxoEDE and 4-Nitrophenol were dramatically elevated. In contrast, a total of 68 differential metabolites were identified in the LNT+NaHCO 3 group (LN group), of which 31 were up-regulated and 37 were down-regulated. The levels of toxic metabolites were dramatically reduced, whereas the beneficial metabolites Octanoylcarnitine and Glu-Glu were significantly raised. The findings revealed that NaHCO 3 exposure caused substantial changes in the composition of fish intestinal microbiota, whereas LNT reduced the toxicity of NaHCO 3 to fish intestinal microbiota. Overall, our results emphasize that LNT can be used as effective additives against carbonate stress in aquaculture, and provide a new strategy for aquatic organism health management in saline environments by regulating the gut microbiota of Carassius auratus and host metabolic interactions. • Lentinan boosts Carassius auratus growth under NaHCO 3 stress. • Lentinan reduces kidney cell apoptosis from NaHCO 3 stress. • Lentinan raises beneficial metabolites and regulates gut flora.