Resumo

The mangrove ecosystem is a tropical coastal biome located at the transition between the land and sea area characterized by periodic floods, which impart unique and specific characteristics to this system features. Chitin is an important polymer in mangrove environment where can be found composing the high concentration of organic matter from the decomposition of the exoskeleton animal (shells of crab, shrimp, clams) and structural elements found in the cell wall of fungi. Chitin is sensitive to natural degradation and in particular some bacterial enzymes are involved in the degradative process. The microbial activity is considered the major route of nutrient cycling in this environment, acting directly in the decomposition of organic matter. in this case, we work in this study using three distinct mangroves located on the coast of São Paulo State where the samples were collected in triplicates separated to access and analysing the bacterial comunity responsible for degrading chitin throught the use of specific primers for amplification. The analysis of the bacterial chitinolytic community structure was realized by DGGE (Denaturing gradient gel eletrophoresis) of chiA gene, using a nested approach by primers specific for bacterial GA1F and GA1R, followed by QAS1 and QAS2. For quantification by qPCR, we used the technique of amplified specific for bacterial ChiA gene and for PCR amplification of the construction of chiA clone libraries; we used the three replicates of each soil. The results demonstrated in the same way, for the ChiA gene also a NMDS plot was generated in which we could observe that there is also a significant difference between the communities present in each location (ANOSIM: R = 0.866, P <0.05). Nevertheless, the locations with and without oil were different among each other, allowing us to suggest that these communities are adapting to the physiological and ecological conditions. Concerning the chiA gene, no significant differences between sites (P> 0.05) were observed, and the abundance of this gene ranged from 105 gene copies per gram of soil. The chiA gene proved to be active on the degradation of chitin, and in this mangrove swamp environment it has been maintained even in contaminated areas, suggesting an important role in the cycling of chitin also participating in the nitrogen and carbon cycle, and futures studies for search and understand the functional genes in this environment.