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Intestinal Microbiota and Species Diversity of Campylobacter and Helicobacter spp. in Migrating Shorebirds in Delaware Bay
Ryu, H., K. Grond, B. Verheijen, M. Elk, D. Buehler, AND J. Santodomingo. Intestinal Microbiota and Species Diversity of Campylobacter and Helicobacter spp. in Migrating Shorebirds in Delaware Bay. APPLIED AND ENVIRONMENTAL MICROBIOLOGY. American Society for Microbiology, Washington, DC, 80(6):1838-1847, (2014).
Shorebirds are sources of fecal pollution in surface waters. The fecal bacteria inhabiting these animals and the potential risks assocaited with them is poorly understood. In order to shed light on the to fecal microbial community of migratory birds we developed and analyzed 16S rDNA fecal clone libraries of three bird species that stopover in Delaware Bay. We also used qPCR assays to determine the presence and relative abundance of fecal bacteria relevant to microbial water quality monitoring. The information generated in this study will also help better develop tools to track migratory birds fecal pollution in stopover sties.
Using rDNA sequencing analysis, we examined the bacterial diversity and the presence of opportunistic bacterial pathogens (i.e., Campylobacter and Helicobacter) in Red Knot (Calidris canutus, n=40), Ruddy Turnstone (Arenaria interpres, n=35), and Semipalmated Sandpiper (Calidris pusilla, n=22) in fecal samples collected during a migratory stopover in Delaware Bay. Additionally, we studied the occurrence of Campylobacter spp., enterococci and waterfowl fecal source marker using qPCR assays. Of 3,889 16S rRNA clone sequences analyzed, the bacterial community was mostly composed of populations closely related to the classes Bacilli (63.5%), Fusobacteria (12.7%), and ε-Proteobacteria (6.5%), Clostridia (5.8%), whereas fewer sequences were classified within the class Bacteroidia (0.2%). When ε-Proteobacteria-specific 23S rRNA gene clone libraries (i.e., 1,414 sequences) were analyzed, the sequences were identified as Campylobacter spp. (82.3%) or Helicobacter spp. (17.7%). Specifically, 38.4%, 10.1%, and 26.0% of clone sequences were identified as C. lari (>99% sequence identity) in Ruddy Turnstone, Red Knot, and Semipalmated Sandpiper clone libraries, respectively. Other pathogenic species of Campylobacter such as C. jejuni and C. coli were not detected in excreta of any of the three bird species. Most Helicobacter-like sequences identified were closely related to H. pametensis (>99% sequence identity) and H. anseris (92% sequence identity), but none of the sequences were closely related to human pathogen H. pylori. Similarly, qPCR results showed the occurrence and abundance of Campylobacter spp. was relatively high compared to fecal indicator bacteria such as Enterococcus spp., Enterococcus faecalis, and Catellicoccus marimammalium. The results of this study provide insights on the complexity of the shorebird gut microbial community and suggest that these migratory birds could be important reservoirs of pathogenic Campylobacter species.