盐度对斑点叉尾鮰肠道菌群的影响

Effect of salinity on intestinal flora of channel catfish (Ictalurus punctatus)

  • 摘要: 斑点叉尾鮰 (Ictalurus punctatus) 是我国盐碱池塘养殖的重要品种,盐度作为关键环境因子,其对斑点叉尾鮰肠道菌群的影响机制尚不明确。为探究盐度对斑点叉尾鮰肠道菌群的影响,实验设置4个盐度梯度:对照组 (S0, 0)、低盐组 (S3, 3‰)、中盐组 (S6, 6‰) 和高盐组 (S9, 9‰),进行为期8周的养殖实验。养殖期间,每2周采集1次肠道内容物,通过16S rRNA测序技术分析肠道菌群组成和功能。结果显示,随着盐度的增加,肠道菌群丰富度上升,但多样性显著下降。在门水平上,优势菌群为变形菌门、厚壁菌门、梭杆菌门、拟杆菌门、蓝藻门 和放线菌门。对照组及中、低盐度组中,肠道菌群呈现出明显的节律性变化,以2周为周期在变形菌门与厚壁菌门、梭杆菌门、拟杆菌门间规律性波动,而高盐度组则破坏了这种变化节律,表现为变形菌门持续占优势的稳定状态。同时,高盐度条件下,肠道菌群功能也发生了显著变化,脂肪酸代谢与降解、维生素和氨基酸降解以及能量代谢等功能丰度显著升高,核苷酸错配、切除和修复等遗传修复功能显著降低。研究表明,高盐度导致斑点叉尾鮰产生了强烈应激反应,增加了能量消耗,最终引起肠道菌群结构和功能的适应性改变。建议在盐碱地开展斑点叉尾鮰养殖时应加强养殖管理,适当提高饲料能量水平,并补充益生菌群以维持肠道菌群平衡。

     

    Abstract: Channel catfish (Ictalurus punctatus) is an important species cultured in saline-alkali water in China. Salinity is a key environmental factor, but the mechanism of its influence on the intestinal flora of I. punctatus is not clear. To investigate theeffect of salinity on the intestinal flora of I. punctatus, we designed an eight-week experiment and divided the fish into four groups: control group (S0, salinity 0), low-salt group (S3, salinity 3‰), medium-salt group (S6, salinity 6‰), and high-salt group (S9, salinity 9‰). The intestinal contents of fish were collected every two weeks, and the composition and function of the intestinal flora were analyzed by 16S rRNA sequencing. The results show that with the increase of salinity, the richness of theintestinal flora increased, but the diversity decreased significantly. On phylum level, Proteobacteria, Firmicutes, Fusobacteriota, Bacteroidetes, Cyanobacteria and Actinobacteria were the dominant bacterial phyla. In the control, low-salt and medium-salt groups, the intestinal flora showed rhythmic changes in the 2-week cycle, regularly repeating between Proteobacteria and Firmicutes, Fusobacteriota, Bacteroidetes. In contrast, the high salinity group disrupted the rhythm of changes, showing a maintenance of the predominance of Proteobacteria. Meanwhile, the functions of the intestinal flora also changed significantly in high-salinity condition, with significantly higher functional abundance in fatty acid metabolism and degradation, vitamin and amino acids degradation, and energy metabolism, and a significant decrease in the genetic repair functions such as mismatchrepair, nucleotide excision repair. High salinity caused strong stress in I. punctatus, increased energy expenditure, and ultimately altered the composition and function of the intestinal flora. Therefore, it is recommended to culture I. punctatus in saline ponds, which requires higher energy and probiotic supplementation in feed.

     

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