Analysis on the bacterial microflora on the amphibian skin of Atlantic Forest fragments and its effectiveness against pathogens.

Author(s)

Ananda Brito de Assis

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB)
• Defense date: 2011-03-14

Examining board members

Carlos Arturo Navas Iannini; Fernando Ribeiro Gomes; Cristina Rossi Nakayama

• Advisor: Carlos Arturo Navas Iannini

Abstract

The skin of amphibians, as well as that of other animals, acts as a first protection barrier against pathogens. The microbial community resident in the amphibian skin is composed of some species of bacteria that may have antibacterial or antifungal action against known pathogens, including Batrachochytrium dendrobatidis, the alleged principal agent Tleading to declines of amphibian populations around the world. Because the chemical and physical variables of the landscape influence the growth, survival and metabolic activity of microorganisms, the function of skin as a protective barrier against infectious agents in amphibians, is likely affected by parameters that are altered in fragmented forest habitats. Thus, it is important to understand how environmental conditions affect the skin microbiota of amphibians, and the possible induced changes on vulnerability of amphibians to pathogens. Our research aimed to characterize the microbial communities living skin of amphibians in two contexts of landscape: fragment and continuous area. The parameters used for this analysis were density and richness of microbial morphotypes of bacterial colonies. The potential inhibition of pathogen growth was also evaluated using a cross-streak test, and some taxa in these communities were identified using international protocols. The observed differences in microbial density and richness across landscapes, and the presence of bacterial taxa typical of given environments, point out to the role of environmental change as an important component determining the profiles of microbial communities living on the skin of amphibians. These changes are very likely consequential, but understanding the scope and nature of consequences require additional study. (AU)