Abundance and Genetic Diversity of nifH Gene Sequences in Anthropogenically Affected Brazilian Mangrove Sediments

Author(s)

Franco Dias, Armando Cavalcante ^{[1, 2]} ; Pereira e Silva, Michele de Cassia ^[3] ; Cotta, Simone Raposo ^[4] ; Dini-Andreote, Francisco ^[3] ; Soares, Jr., Fabio Lino ^[2] ; Salles, Joana Falcao ^[3] ; Azevedo, Joao Lucio ^[2] ; van Elsas, Jan Dirk ^[3] ; Andreote, Fernando Dini ^[1]

Affiliation

^[1] Univ Sao Paulo, Dept Soil Sci, ESALQ USP, Piracicaba - Brazil

^[2] Univ Sao Paulo, Ctr Nucl Energy Agr, CENA USP, Piracicaba - Brazil

^[3] Univ Groningen RUG, Dept Microbial Ecol, CEES, Groningen - Netherlands

^[4] Univ Rio de Janeiro, URFJ RJ, Dept Microbiol Paulo de Goes, Rio De Janeiro - Brazil

• Document type: Journal article
• Source: Applied and Environmental Microbiology; v. 78, n. 22, p. 7960-7967, NOV 2012.
• Web of Science Citations: 20

Abstract

Although mangroves represent ecosystems of global importance, the genetic diversity and abundance of functional genes that are key to their functioning scarcely have been explored. Here, we present a survey based on the nifH gene across transects of sediments of two mangrove systems located along the coast line of Sao Paulo state (Brazil) which differed by degree of disturbance, i.e., an oil-spill-affected and an unaffected mangrove. The diazotrophic communities were assessed by denaturing gradient gel electrophoresis (DGGE), quantitative PCR (qPCR), and clone libraries. The nifH gene abundance was similar across the two mangrove sediment systems, as evidenced by qPCR. However, the nifH-based PCR-DGGE profiles revealed clear differences between the mangroves. Moreover, shifts in the nifH gene diversities were noted along the land-sea transect within the previously oiled mangrove. The nifH gene diversity depicted the presence of nitrogen-fixing bacteria affiliated with a wide range of taxa, encompassing members of the Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Firmicutes, and also a group of anaerobic sulfate-reducing bacteria. We also detected a unique mangrove-specific cluster of sequences denoted Mgv-nifH. Our results indicate that nitrogen-fixing bacterial guilds can be partially endemic to mangroves, and these communities are modulated by oil contamination, which has important implications for conservation strategies. (AU)

• FAPESP's process: 04/13910-6 - Biodiversity and functional activities of microorganisms from mangrove of the State of São Paulo
• Grantee: Itamar Soares de Melo
• Support Opportunities: BIOTA-FAPESP Program - Thematic Grants
• FAPESP's process: 08/54013-8 - Diversity of archaea and bacteria involved in the nitrogen cycling in mangrove sediments
• Grantee: Armando Cavalcante Franco Dias
• Support Opportunities: Scholarships in Brazil - Doctorate