|SEAGULL- Identification of nonpoint sources of faecal pollution in a natural environment: contributing data for risk assessment|
Anabela de Oliveira Pereira
Programme - PTDC/AAC-AMB/109155/2008
Execution dates - 2010-04-05 - 2013-10-04 (42 Months)
Funding Entity - FCT
Funding for CESAM - 147501
Total Funding - 163501
Proponent Institution - Universidade de Aveiro
Instituto Politécnico de Leiria
Faecal contamination on coastal environments affects shellfish and water quality and safety and causes economic losses due to closure of shellfish harvesting areas and water systems used for recreation. Furthermore, faecal pollution can pose a high health risk to people who come into contact with contaminated water, because of the presence of potentially pathogenic microorganisms. These may be derived from a variety of human or nonhuman sources. On many cases, wild animals contribute with the majority of the organic pollution and, due to its diffuse nature, this contamination may be more difficult to control. Seabirds constitute one of the sources of nonpoint pollution. Seagull species are common shore waterfowl species and their faeces are considered a major source of contamination in coastal waters. Several studies have shown that seagull faeces may carry human pathogens and may contribute to the dissemination of drug-resistance genes. Therefore, we propose to study a specific environment in Portugal, the Berlengas archipelago, in which seagulls are common and whose population has increased significantly. Berlengas islands are part of the Berlengas Natural Reserve and it belongs to the National Network of the Protected Areas. Microbiological analysis of water from the public beach show high levels of total coliforms and Escherichia coli. Point sources are not known in the archipelago, but considering a small human resident population and a massive population of seagulls, we hypothesize that sea birds are the main origin of faecal contamination in this environment. The identification of the source of faecal pollution is crucial for health risk assessment and development of appropriate supervision practices to control and prevent further contamination. Also, obtaining information on the specific characteristics of seagulls faecal microorganisms, namely on their antibiotic-resistance profiles, resistance genotypes and virulence-related characteristics, will constitute a step forward in the assessment of human health risk that this kind of contamination constitutes. The main aims of this research proposal are (I) to identify the source of the faecal pollution detected in a public beach; (II) to assess human health risks from seagulls faecal pollution. To investigate the origin of the high levels of faecal coliforms and E. coli presents in the beach of Berlengas Islands we will use Microbial Source Tracking (MST) methods based on culture-dependent and culture-independent approaches. Specifically, culture-dependent approaches will include genotyping methods based on DNA fingerprinting of bacterial isolates, such as PFGE and REP-PCR and phenotypic methods such as antibiotic resistance analysis (ARA). For this experiments a culture collection of E. coli isolates will be used, which are common in the faecal material and are traditionally used in MST culture-dependent approaches. Culture-dependent standard methods will be combined with MST culture-independent methods. This approach involves the detection of indicator genes and the analysis of their molecular diversity by PCR-DGGE to obtain sample-specific profiles using general Bacteroidetes primers. Anaerobic Bacteria such as Bacteroidetes has been suggested as alternative host-specific faecal indicators as opposed to faecal coliform, E. coli. Also, primers targeting avian specific microorganisms will be used in standard PCR and real-time PCR approaches to detect seagulls-specific contamination. To assess human health risks from seagull faecal pollution we will look for plasmid and integrons occurrence and associated encoded genes in bacteria culture collections from seagull faecal material. Additionally, a screening for a range of different antibiotic-resistance genes and virulence factors will be done by using specific previously reported PCR primers. Finally extra-cellular activities previously implicated in pathogenesis will be detected. We expect to clearly identify the contamination source on Berlengas islands. Also, the fact that an array of MST methodologies will be optimized and applied will raise the consistency of our results and will facilitate the choice of appropriate methodologies for routinely monitorize the sources of pollution on this and other similar environments. Finally the information obtained from the characterization of seagulls E. coli will elucidate the risk that this contamination constitutes to human and ecological health. The overall results of the proposed research will constitute an important contribution as support for public health authorities and environmental protection agencies to implement proper management strategy for improving the quality of surface waters. The proponents of this application have the necessary knowledge to conduct the analysis here proposed. Members of this multidisciplinary research team are highly experienced in different research areas such as Molecular Microbiology, Environmental Microbiology and Biochemistry.
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