ANDREOTE, F. D.

AZEVEDO, J. L.

DIAS, A. C. F.

ELSAS, J. D. van

MELO, I. S. de

SALLES, J. F.

SILVA, M. C. P. e

RCAAP - Repositório Científico de Acesso Aberto de Portugal

Linking the edges of microbially-mediated nitrogen transformations in mangrove sediments.

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P2.06 linking the edges of microbially-mediated nitrogen transformations in,,~\mangrove sedimentsArmando Cavalcante Franco Dias}, Michele Cassio Pereira e Silvo', Joana Falcão Soltes', João LúcioAzevedo', Itamar Soares de Meto", Jan Dirk van Elsa/ and Fernando Dini Andreote"'Center for Nuclear Energy in Agriculture, University of SãoPaulo, CENA/USP,Piracicaba,BrazillDepartment of Microbial Ecology,Centre for Ecological and Evolutionary Studies (CEES),University ofGroningen (RUG),Nijenborgh 7, 9747AGGroningen, The Netherlands3Laboratory of Environmental Microbiology, CNPMA- Embrapa Environment, Jaguariúna, Brazil"Departrnent of Soil Science,ESALQ/USP,University of SãoPaulo, Piracicaba, BrazilCorresponding mail: A.C.F.Dias.dias147@gmail.comMicrobially-mediated ecosystem functions, such as N2 fixation and denitrification, can beinfluenced by both the structure and activity of the residing microbial community, which mightrespond differently to anthropogenic disturbances. Due to the vertical stratification of the aerobic,microaerophilic and anaerobic zones, mangroves are important hot spots for microbial activity.However, the N2 fixation and denitrification processes have been not extensively assessed in theseecosystems. Here, we present a survey based on mangrove sediments using samples taken inthree different mangroves located at the coast of São Paulo State (Brazil), and varying according totheir degree of disturbance: i) oil-contaminated mangrove at Bertioga, ii) mangrove under thepressure of anthropogenic activity at Bertioga, iii) non-disturbed mangrove at Cardoso Island -Cananéia. Functional microbial communities possibly involved in these transformations wereassessed by denaturing gradient gel electrophoresis (DGGE) and quantitative PCR, using the nifHand nosZ genes as markers for nitrogen fixation and denitrification, respectively. DGGEanalysis ofnifH gene showed differences among the mangroves and also revealed c1ear differences amongthe sampling points across the transect sea-Iand. Despite the difference in community structure,the abundance of nitrogen fixers remained constant at ali points within the mangrove andbetween the sediments of three mangroves (Iog values ranging from 6.0 to 7.9 copies per gram ofsediment). Results based on nosZ showed higher abundance of denitrifiers was higher than ofnitrogen fixers (Iog values ranging from 7.5 to 8.5 copies per gram of sediment), possibly related tothe anaerobic conditions of the mangroves, favoring denitrification. Moreover, denitrifiers werepresent in higher abundance in the mangrove at Cananéia compared to Bertioga, indicating thatdisturbances have a great impact on the size of these communities. In summary, our findingsrevealed that denitrifiers and nitrogen fixers coexist in the mangrove sediment, althoughmangrove sediments sustain a higher abundance of the former. Moreover, the observed changesin community density and structure indicate that the preservation state of the mangroves isdirectly involved with the nitrogen transformations in these sediments.114

Linking the edges of microbially-mediated nitrogen transformations in mangrove sediments.

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RCAAP - Repositório Científico de Acesso Aberto de Portugal

Repository Open Access to Scientific Information from Embrapa