Publicação
Diversity of the cutaneous bacterial community in the Perez’ frog
| Resumo: | Amphibian skin holds a resident bacterial community in the skin surface may confer amphibian species tolerance to environmental stressors. Exposure to chemical contamination may cause direct effects to the amphibians but, simultaneously, may reduce skin bacterial diversity and consequently alter the sensitivity of amphibians to future environmental stressors. Understanding the structure, dynamics and specificity of this microbial community is needed to engage a better and broader protection of amphibians. Accordingly, the present study aimed at investigating the skin-associated bacterial community of the Perez´s frog Pelophylax perezi (Seoane) looking at among and within population variation. To attain this main goal the outer microbiome of the frogs were characterize by culture independent method (PCR/DGGE) and assessing the cultivable portion of bacteria. Furthermore, to evaluate the effects caused by exposure to chemical contamination in the skin bacterial community, some bacterial isolates were exposed to a rich metal contaminated effluent. Skin swabs for sampling symbiotic skin bacteria were collected from 28 amphibian individuals from five different ponds, one of them a metal-rich contaminated effluent (Ribeira da Agua Forte, Aljustrel). For each sampling site physical and chemical characterization of water samples was carried out. A culture independent method showed a characteristic profile in frogs from contaminated site and that both intra- and inter-population variability exist in amphibian skin microbiome. Assessing the cultivable portion of bacteria, microbial concentration per amphibian varied within animals from the same environment and between animals from different environments. Results revealed low diversity and bacterial density (CFU/ frog swab sample) on individuals from metal contaminated site. Isolated bacteria were genetically identified based on 16S rRNA gene sequence. Ecotoxicological assays exposing 30 bacterial isolates to the metal contaminated effluent showed that the percentage of resistant isolates was higher in frogs from the contaminated site. It was also observed that those bacteria exposed to effluent presented a delay in their growth rate. |
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| Autores principais: | Costa, Sara Daniela Azevedo |
| Assunto: | Ecologia Anfíbios - Pele Metais - Poluição de água Comunidades microbiológicas |
| Ano: | 2013 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade de Aveiro |
| Idioma: | inglês |
| Origem: | RIA - Repositório Institucional da Universidade de Aveiro |
| Resumo: | Amphibian skin holds a resident bacterial community in the skin surface may confer amphibian species tolerance to environmental stressors. Exposure to chemical contamination may cause direct effects to the amphibians but, simultaneously, may reduce skin bacterial diversity and consequently alter the sensitivity of amphibians to future environmental stressors. Understanding the structure, dynamics and specificity of this microbial community is needed to engage a better and broader protection of amphibians. Accordingly, the present study aimed at investigating the skin-associated bacterial community of the Perez´s frog Pelophylax perezi (Seoane) looking at among and within population variation. To attain this main goal the outer microbiome of the frogs were characterize by culture independent method (PCR/DGGE) and assessing the cultivable portion of bacteria. Furthermore, to evaluate the effects caused by exposure to chemical contamination in the skin bacterial community, some bacterial isolates were exposed to a rich metal contaminated effluent. Skin swabs for sampling symbiotic skin bacteria were collected from 28 amphibian individuals from five different ponds, one of them a metal-rich contaminated effluent (Ribeira da Agua Forte, Aljustrel). For each sampling site physical and chemical characterization of water samples was carried out. A culture independent method showed a characteristic profile in frogs from contaminated site and that both intra- and inter-population variability exist in amphibian skin microbiome. Assessing the cultivable portion of bacteria, microbial concentration per amphibian varied within animals from the same environment and between animals from different environments. Results revealed low diversity and bacterial density (CFU/ frog swab sample) on individuals from metal contaminated site. Isolated bacteria were genetically identified based on 16S rRNA gene sequence. Ecotoxicological assays exposing 30 bacterial isolates to the metal contaminated effluent showed that the percentage of resistant isolates was higher in frogs from the contaminated site. It was also observed that those bacteria exposed to effluent presented a delay in their growth rate. |
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