Response of gut microbiota to feed‐borne bacteria depends on fish growth rate: a snapshot survey of farmed juvenile Takifugu obscurus

Summary Environmental bacteria have a great impact on fish gut microbiota, yet little is known as to where fish acquire their gut symbionts, and how gut microbiota response to the disturbance from environmental bacteria. Through the integrative analysis by community profiling and source tracking, we show that feed‐associated bacteria can impose a strong disturbance upon the hindgut microbiota of cultured fugu. Consequently, marked alterations in the composition and function of gut microbiota in slow growth fugu were observed, implying a reduced stability upon bacterial disturbance from feed. Moreover, quantitative ecological analyses indicated that homogeneous selection and dispersal limitation largely contribute to the community stability and partial variations among hosts in the context of lower degree of disturbance. While the disturbance peaked, variable selection leads to an augmented interaction within gut microbiota, entailing community unstability and shift. Our findings emphasized the intricate linkage between feed and gut microbiota and highlighted the importance of resolving the feed source signal before the conclusion of comparative analysis of microbiota can be drawn. Our results provide a deeper insight into aquaculture of fugu and other economically important fishes and have further implications for an improved understanding of host–microbe interactions in the vertebrate gastrointestinal tract.