Abstract:

To investigate the effects of Bacillus subtilis as water additive on gut microbiota in Spinibarbus caldwelli, Acrossheilus hemispinus and Hypophthalmichthys molitrix and its purification effect on aquaculture water, the gut microflora in the foregut, midgut and hindgut of three fishes were investigated through 16S rDNA sequencing and the pH, the levels of ammonia nitrogen and nitrite in the aquatic water were measured. The results suggested B.subtilis could reduce the contents of ammonia nitrogen by 46.39% in water stably since the 11th day and nitrite by 84.61% in water stably since the 19th day. The gut microflora in each intestinal site between experiment and control group were significantly different overall and the abundance of intestinal flora decreased in the experiment group. On the whole,in experiment group, the abundance of intestinal microbiota decreased and the phylum abundance of Actinobacteria and Planctomycetes increased and decreased, respectively. The genus levels of Bacillus increased while pathogenic bacteria Aeromonas and Vibrio decreased. The KEGG signal pathways showed that the metabolic functions of the H.molitrix were enhanced. This study showed that B.subtilis could reduce the level of ammonia nitrogen and nitritein in the aquatic water and purify the aquatic wate, while inhibiting the propagation of harmful intestinal microbiota and improving the metabolic level of intestinal microbiota in H.molitrix.

Key words: Bacillus subtili, water purification, intestinal microbiota, Spinibarbus caldwelli, Acrossheilus hemispinus, Hypophthalmichthys molitrix

摘要：

为了探讨水体投放枯草芽孢杆菌(Bacillus subtilis)对黑脊倒刺鲃(Spinibarbus caldwelli)、半刺厚唇鱼(Acrossheilus hemispinus)和鲢(Hypophthalmichthys molitrix)等不同习性鱼类肠道微生物菌群的影响以及对养殖水体的净化效果,实验采用16S rDNA测序分析了该3种实验鱼前、中、后肠的菌群结构,并测定分析养殖水体pH、氨氮和亚硝酸盐含量变化。结果表明:投放枯草芽孢杆菌11 d起能够稳定降低水体中46.39%氨氮含量,自19 d 起能够稳定降低水体中84.61%亚硝酸盐含量。16S rDNA肠道菌群分析结果显示:枯草芽孢杆菌实验组和对照组各肠道部位菌群整体区分明显,实验组肠道菌群丰度降低。整体而言,实验组放线菌门呈上升趋势,而浮霉菌门呈下降趋势,芽孢杆菌属在各肠道丰度提高,常见水产致病菌气单胞属和弧菌属丰度均降低。KEGG信号通路富集结果显示,鲢投放枯草芽孢杆菌组肠道菌群代谢功能加强。水体投放枯草芽孢杆菌实验证明,枯草芽孢杆菌可以降低水体氨氮、亚硝酸盐含量,起到净化水质的作用,同时可抑制鱼体肠道有害菌群的繁殖,提高鲢肠道菌群代谢水平。

关键词: 枯草芽孢杆菌, 水体净化, 肠道菌群, 黑脊倒刺鲃, 半刺厚唇鱼, 鲢