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The animal gut harbors diverse microbes that play a profound role in thenutrition uptake,metabolism,and regulation of immune of their host.The intestinal microbiota homeostasis is critical for health but is poorly understood.In this study,we compared the effects of probiotics,including Paracoccus marcusii DB11 and Bacillus cereus G19,and antibiotics florfenicol on the intestinal microbial community composition and species-species interaction in sea cucumber(Apostichopus japonicus Selenka)by high-throughput 16S rDNA sequencing.Dietary supplementation obviously changed the intestinal microbial community with a remarkable decrease in proportion of Flavobacteriia in sea cucumber,but those still shared the same core microbiota with sea cucumber in the control group such as Flavobacteriaceae,Rhodobacteraceae,and Vibrionaceae.Molecular ecological network analysis suggested that the compositions of ecological networks within intestinal microbiota is similar to intestinal microflora.Daily consumption of B.cereus G19 or P.marcusii DB11 could promote intestinal microbiota homeostasisby improving modularity,enhancing species-species interactions and increasing the number of connecters and/or module hubs within the ecological network.In contrast,the use of florfenicol can lead to the collapse of intestinal microbiota homeostasis throughdeteriorating the ecological networkby reducing the number of connecters and module hubs.