Salinity is one of the important factors affecting the physiological state of crustaceans in marine environments. Lipid plays major roles in energy supply and is main sources of essential fatty acids for membrane integrity, which is critical in adaptations to changes in salinity. Here we evaluated the effects of salinity (medium, 23 ppt and low, 4 ppt) and dietary lipid source (fish oil, FO and soybean oil, SO) on intestinal health of the marine crustacean mud crab Scylla paramamosain. The results indicated that low salinity and dietary SO (LSO group) significantly affected intestinal histomorphology, with a significant decrease of intestinal fold height and width as well as down-regulation of intestinal mRNA levels of tight junction genes compared to crab reared at medium salinity and fed FO diets (MFO group). Crabs reared at low salinity and fed SO showed an increased inflammatory response in intestine, which stimulated a physiological detoxification response together with apoptosis compared to crab in the MFO group. Low salinity and SO diets also could be responsible for multiply the pathogenic bacteria of Photobacterium and inhibit the beneficial bacteria of Firmicutes and Rhodobacteraceae in intestine, and act on a crucial impact on the development of intestinal microbial barrier disorders. The results of microbial function predictive analysis also support these inferences. The findings of the present study demonstrated that soybean oil as the main dietary lipid source could exacerbate the adverse effects of low salinity on intestinal health of mud crab, and provided evidence suggesting that dietary lipid source and fatty acid composition may play vital roles in intestinal health and the process of adaptation to environmental salinity in marine crustaceans.

盐度是影响海洋环境中甲壳类动物生理状态的重要因素之一。脂质在能量供应中起着重要作用，并且是用于膜完整性的必需脂肪酸的主要来源，这对于适应盐度变化至关重要。在这里，我们评估了盐度（中等，23 ppt和低，4 ppt）和饮食脂质源（鱼油，FO和大豆油，SO）对海洋甲壳类泥蟹Scylla paramamosain肠道健康的影响。结果表明，与在中等盐度和高盐下饲养的蟹相比，低盐度和饮食中的SO（LSO组）显着影响肠道组织形态，与紧密连接基因相比，肠折叠高度和宽度显着下降，并且紧密连接基因的肠mRNA水平下调。喂FO食品（MFO组）。与MFO组的螃蟹相比，以低盐度饲养并喂食SO的螃蟹在肠道中显示出增加的炎症反应，从而刺激了生理性解毒反应以及细胞凋亡。低盐度和SO饮食也可能导致光致细菌的致病菌繁殖，并抑制肠道中的Firmicutes和Rhodobacteraceae的有益细菌，并对肠道微生物屏障疾病的发展产生关键影响。微生物功能预测分析的结果也支持这些推论。本研究的结果表明，大豆油作为主要的膳食脂质来源可以加剧低盐度对泥蟹肠道健康的不利影响，并提供证据表明膳食脂质来源和脂肪酸组成可能在肠道健康中起着至关重要的作用。以及海洋甲壳类动物对环境盐分的适应过程。