Intestinal microbiota of Galapagos iguanas and Aeolian sea turtles

To preserve environment and biodiversity is a major challenge of modern science. In the strategy of conservation, based on the implementation of basic knowledge, the identification of the intestinal microbiota of wild organisms (i.e. land iguanas from the Galapagos Islands and turtles from the Aeolian Islands) can be used as both basic knowledge and application tool.The quantitative and qualitative definition of microorganisms inhabiting the digestive tract of these reptiles, can provide an overview of great interest and it is still largely unexplored, while the comparison of the intestinal microbiota from urbanized and wild areas, can be another way to assess the impact of human presence.

The transfer of antibiotic resistance is a marker to follow the exchange of microorganisms between the man-impacted and natural compartments. The analysis of the incidence and nature of the genetic determinants of antibiotic resistance that occur naturally and/or are acquired by enteric bacteria of the intestinal microbiota, is an additional tool for evaluating the human impact by comparing the results found in animals from urbanized areas or intact ones.The work was started on land iguanas from the Galapagos Archipelago, a particularly interesting case because some islands are not exposed to human impact and so we can have some indication of the wildlife in the absence of disturbances, while others are subject to human impact (indigenous and/or tourists). From this system it is possible to get information on both the changes that already took place and on those in progress: a sort of "experiment-control" structure. The project included both the identification of the main components of the microbiota associated with the cloaca of land and marine iguanas, both the incidence and nature of resistance determinants.

The same work is in progress on land iguanas of the French Antilles, in the Caribbean Sea.With the same objective the intestinal microbiota and the incidence and nature of the determinants of resistance was studied in sea turtles (Caretta caretta L.) sampled in the Aeolian Islands, around the island of Filicudi. In this case the gut microbiome of turtles in good health conditions and others with discomforts, due to hooks or plastic bags ingested, were compared.

This project is carried out in collaboration: for the iguanas, with Gabriele Gentile, Department of Biology, Tor Vergata, who works since many years with the Parque Nacional de Galápagos (Ecuador) and Gian Maria Rossolini, Universities of Florence and Sienna; for sea turtles, with Monica Blasi, Filicudi Wildlife Conservation Association and Daniela Mattei, National Institute of Health in Rome.

 

Thaller M.C., Migliore L., Marquez C., Tapia W., Cedeño V., Rossolini G.M., Gentile G. (2010). TRACKING ACQUIRED ANTIBIOTIC RESISTANCE IN COMMENSAL BACTERIA OF GALÁPAGOS LAND IGUANAS: NO MAN, NO RESISTANCE. PLoS One, 5(2): e8989. DOI: 10.1371/journal.pone.0008989

 
Background: Antibiotic resistance, evolving and spreading among bacterial pathogens, poses a serious threat to human health. Antibiotic use for clinical, veterinary and agricultural practices provides the major selective pressure for emergence and persistence of acquired resistance determinants. However, resistance has also been found in the absence of antibiotic exposure, such as in bacteria from wildlife, raising a question about the mechanisms of emergence and persistence of resistant strains under similar conditions, and the implications for resistance control strategies. Since previous studies yielded some contrasting results, possibly due to differences in the ecological landscapes of the studied wildlife, we further investigated this issue in wildlife from a remote setting of the Galapagos archipelago.
Methodology/Principal Findings: Screening for acquired antibiotic resistance was carried out in commensal enterobacteria from Conolophus pallidus, the terrestrial iguana of Isla Santa Fe, where: i) the abiotic conditions ensure to microbes good survival possibilities in the environment; ii) the animal density and their habits favour microbial circulation between individuals; and iii) there is no history of antibiotic exposure and the impact of humans and introduced animal species is minimal except for restricted areas. Results revealed that acquired antibiotic resistance traits were exceedingly rare among bacteria, occurring only as non-dominant strains from an area of minor human impact.
Conclusions/Significance: Where both the exposure to antibiotics and the anthropic pressure are minimal, acquired antibiotic resistance traits are not normally found in bacteria from wildlife, even if the ecological landscape is highly favourable to bacterial circulation among animals. Monitoring antibiotic resistance in wildlife from remote areas could also be a useful tool to evaluate the impact of anthropic pressure.
 
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Thaller M.C., Ciambotta M., Sapochetti M., Migliore L., Tapia W., Cedeño V., Gentile G. (2010). UNEVEN FREQUENCY OF Vibrio alginolyticus-GROUP ISOLATES AMONG DIFFERENT POPULATIONS OF GALÁPAGOS MARINE IGUANA (Amblyrhynchus cristatus). Environmental Microbiology Reports, 2(1): 179-184. DOI:  10.1111/j.1758-2229.2009.00132.x
 
The presence of Vibrio isolates was investigated in cloacal swabs from the Galápagos marine iguana (Amblyrhyncus cristatus). Such unique iguana is endemic to the Galápagos Archipelago, it is listed as vulnerable in the IUCN Red List (2009), and is strictly protected by CITES and Ecuador laws. Our results revealed an uneven isolation frequency of vibrios from animals living in different settings: maximal among the Santa Fe population, scarce at Bahía Tortuga but practically absent in the samples from Puerto Ayora and Plaza Sur. A 16S sequencing confirmed that the isolates belonged to the genus Vibrio, placing them within the V. alginolyticus group; the biochemical identification was, indeed, consistent with V. alginolyticus features. The reason of the observed discrepancy is not clear, but could be either linked to an higher pollution in the inhabited or more touristic places or to differential influence of chemical and physical parameters at a local scale. As V. alginolyticus is an opportunistic pathogen for man and it is known to cause disease in sea-living animals, the ability of these vibrios to enter and persist to a certain extent in the marine iguana gut should be regarded as a risk for health of both the animals and the human personnel involved in monitoring activities.
 

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Luciana mostra l’iguana rosa (Conolophus marthae), n. 100, vulcano Wolf, Galapagos, giugno 2009.