Diversity of diazotróficas bacteria associates a Araucaria angustifolin the State of São Paulo

Author(s)

Rafaela de Fátima Neroni

• Document type: Master's Dissertation
• Press: Piracicaba. , ilustrações.
• Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
• Defense date: 2007-09-04
• Advisor: Elke Jurandy Bran Nogueira Cardoso
• Field of knowledge: Agronomical Sciences - Agronomy
• Indexed in: Banco de Dados Bibliográficos da USP-DEDALUS
• Location: Universidade de São Paulo. Biblioteca Central da Escola Superior de Agricultura Luiz de Queiroz; t634.975 90334; N452d

Abstract

Araucaria angustifolia is an environmentally threatened tree and the whole biota of the Araucaria Forest should be investigated with the purpose of its preservation. Nitrogen fixing bacteria (diazotrophic bacteria) are extremely important for the maintenance of ecosystems, but their occurrence and diversity have never been studied in A. angustifolia. In our study, soil and Araucaria root samples were collected in three areas in Campos do Jordão State Park, SP, and these samples contained diazotrophic bacteria, as demonstrated by their growth in nitrogen-free semi-solid culture media (NFb, JNFb and LGI). Seventy three bacterial isolates were recovered and four of them had the diazotrophic character confirmed through the increase in the total nitrogen concentration of de media and the acetylene reduction assay. The isolates were classified in 37 phenotypic groups, according to the morphologic characterization of the colonies and change of pH in a combined carbon medium after 24 hours growth. The partial sequencing of the 16S rRNA gene in 62 isolates allowed their classification in eight genotypic groups: Pseudomonas, Burkholderia, Yersinia, Xhantomonas, Janthinobacterium, Brevundimonas, Brucella and Novosphingobium. Divergences were observed comparing phenotypic and genotypic results, and phenotypic evaluation must be considered inadequate for the grouping of the isolates. Peudomonas and Burkholderia were predominated in both the soil and Araucaria root samples. According to the phylogenetic analysis most of the isolates are related to taxonomic groups described as diazotrophis or as plant growth-promoting rhizobacteria (AU)

• FAPESP's process: 05/53047-8 - Diversity of diazotrophic microorganisms under the narrowleaf Atlantic Rainforest in the State of São Paulo
• Grantee: Rafaela de Fátima Neroni
• Support Opportunities: Scholarships in Brazil - Master