Fish gut microbiota analysis differentiates physiology and behavior of invasive Asian carp and indigenous American fish

Abstract

Gut microbiota of invasive Asian silver carp (SVCP) and indigenous planktivorous gizzard shad (GZSD) in Mississippi river basin were compared using 16S rRNA gene pyrosequencing. Analysis of more than 440 000 quality-filtered sequences obtained from the foregut and hindgut of GZSD and SVCP revealed high microbial diversity in these samples. GZSD hindgut (GZSD_H) samples (n ¼ 23) with 47000 operational taxonomy units (OTUs) exhibited the highest alpha-diversity indices followed by SVCP foregut (n ¼ 15), GZSD foregut (n ¼ 9) and SVCP hindgut (SVCP_H) (n ¼ 24). UniFrac distance-based non-metric multidimensional scaling (NMDS) analysis showed that the microbiota of GZSD_H and SVCP_H were clearly separated into two clusters: samples in the GZSD cluster were observed to vary by sampling location and samples in the SVCP cluster by sampling date. NMDS further revealed distinct microbial community between foregut to hindgut for individual GZSD and SVCP. Cyanobacteria, Proteobacteria, Actinobacteria and Bacteroidetes were detected as the predominant phyla regardless of fish or gut type. The high abundance of Cyanobacteria observed was possibly supported by their role as the fish's major food source. Furthermore, unique and shared OTUs and OTUs in each gut type were identified, three OTUs from the order Bacteroidales, the genus Bacillariophyta and the genus Clostridium were found significantly more abundant in GZSD_H (14.9-22.8%) than in SVCP_H (0.13-4.1%) samples. These differences were presumably caused by the differences in the type of food sources including bacteria ingested, the gut morphology and digestion, and the physiological behavior between GZSD and SVCP.

Gut content microbiota of introduced bigheaded carps ( Hypophthalmichthys spp.) inhabiting the largest shallow lake in Central Europe

“…The particular intestinal bacterial communities found in bigheaded carps and the dissimilar microbial compositions characteristic to different sections of the digestive tract were in accordance with the findings of other studies (Li et al, 2014;Ye et al, 2014). The remarkable change in composition between gut sections can be attributed to the digestion process that takes place between the foregut and hindgut and difference in the chemical environment of the two gut sections (Sullam et al, 2012).…”

“…In contrast, Fusobacteria were detected only in a minor proportion in the gut contents of bigheaded carps collected in China and in the United States (Li et al, 2014;Ye et al, 2014). In the alimentary tract of bigheaded carps living in Lake Balaton, obligate anaerobic (e.g.…”

“…Aeromonas and Shewanella) bacteria were frequently detected. These bacteria were found in the intestines of different other fish species too (Sugita et al, 1991;Sugita et al, 1995;Tsuchiya et al, 2008;Li et al, 2014;Ye et al, 2014;Pekala et al, 2015). Moreover, unique taxa (e.g.…”

“…Cyanobacteria were predominant in the gut microbiota of fish inhabiting different rivers of the USA (Ye et al, 2014), while their abundance was very low in the intestinal microbiota of both silver carp and bighead carp living in the shallow Wuhu Lake, China (Li et al, 2014).…”

“…genetic and physiological features of the host) and external factors (e.g. the trophic status of the habitat or the feeding habits of the fish) (Li et al, 2014;Ye et al, 2014;Li et al, 2015). Accordingly, bigheaded carps are ideal study objects to investigate the trophic interaction between bacteria and fish.…”