Diversity of gut microbiota in Japanese pufferfish and wrasses as determined by next-generation sequencing.

The gut microbiota of four tiger puffer (Takifugu rubripes), five grass puffer (T. alboplumbeus), one multicolorfin rainbowfish (Parajulis poecilepterus) and one bambooleaf wrasse (Pseudolabrus sieboldin) collected from coastal waters, along with four raised tiger puffer were analyzed using nextgeneration sequencing (NGS). As a result, Alphaproteobacteria (mean ± SEM, 16.6 ± 3.3%), Clostridia (13.9 ± 3.5%), Gammaproteobacteria (12.6 ± 2.8%), Epsilonproteobacteria (9.9 ± 6.6%), Bacilli (8.6 ± 3.4%), and Planctomycetia (6.4 ± 1.8%) had high relative abundance in more than 80% of the samples. The UPGMA dendrogram using the Bray-Curtis similarity index showed that the gut microbiota was similar among raised individuals of tiger puffer, whereas there are large individual differences among wild fishes, including tiger puffer, grass puffer and wrasses probably due to differences in their individual histories. Vibrionaceae were detected in 13 of 15 samples and the mean relative abundance of Vibrionaceae, including the genera Aliivibrio, Enterovibrio, Photobacterium, Salinivibrio and Vibrio was 3.981 ± 1.503%, which was estimated to be 3.5 x 10⁵-4.9 x 10⁸ cells/g. However, Vibrionaceae was not detected in two wild grass puffer samples, suggesting their absence or presence at densities too low to be detected by NGS. These results confirm that the density of Vibrionaceae in guts of coastal fishes varies widely. In addition, sequences of Cetobacterium somerae, a known dominant anaerobe of freshwater fish, and Epulopiscium fishelsoni, a giant bacterium larger than 600 μm x 80 μm, were detected, with mean relative abundances when present of 0.158 ± 0. 087% and 0.456 ± 0.176%, respectively. [ABSTRACT FROM AUTHOR]