title: Crop management as a driving force of plant growth promoting rhizobacteria physiology.
abstract: Crop management systems influence plant productivity and nutrient use efficiency, as well as plant growth-promoting rhizobacteria (PGPR), which are known to influence the growth of plants via phytohormone production, phosphate solubilization, nitrogen (N) fixation and antimicrobial activity. The objective of this study was to compare the influence of two crop management system on microbial PGPR features. PGPR isolated from the rhizospheres of Carica papaya L. grown under two distinct management systems (conventional and organic) were identified and characterized. The 12 strains most efficient in solubilizing inorganic phosphate belonged to the genera Burkholderia, Klebsiella, and Leclercia. N fixation was observed in the strains B. vietnamiensis from the conventional farming system and B. vietnamiensis, B. cepacia and Leclercia sp. from the organic farming system. The B. vietnamiensis, B. cepacia, Klebsiella sp. and Klebsiella sp. isolates showed antifungal activity, while Leclercia sp. did not. The strains B. vietnamiensis and Enterobcter sp. (isolated from the conventional farming system) and Klebsiella sp. (isolated from the organic farming system) were efficient at solubilizing phosphate, producing phytohormones and siderophores, and inhibiting the mycelial growth of various phytopathogenic fungi (Botrytis cinerea, Pestalotia sp., Alternaria sp., Phoma sp., Fusarium culmorum, Geotrichum candidum). Physiological differences between the isolates from the two crop management regimes were distinguishable after 10 years of distinct management.
authors.affiliation: Ecosystems Ecology Unit, Universidade Vila Velha (UVV), Vila Velha, ES 29102-920 Brazil ; Center for Ecology, Evolution and Environmental Changes, Faculdade de Ciências, Universidade de Lisboa, 1649-004 Lisbon, Portugal.
authors.forename: Juliana
authors.initials: J
authors.lastname: Melo
authors.affiliation: Center for Ecology, Evolution and Environmental Changes, Faculdade de Ciências, Universidade de Lisboa, 1649-004 Lisbon, Portugal.
authors.forename: Manuela
authors.initials: M
authors.lastname: Carolino
authors.affiliation: Center for Ecology, Evolution and Environmental Changes, Faculdade de Ciências, Universidade de Lisboa, 1649-004 Lisbon, Portugal.
authors.forename: Luís
authors.initials: L
authors.lastname: Carvalho
authors.affiliation: Center for Ecology, Evolution and Environmental Changes, Faculdade de Ciências, Universidade de Lisboa, 1649-004 Lisbon, Portugal.
authors.forename: Patrícia
authors.initials: P
authors.lastname: Correia
authors.affiliation: Center for Biodiversity, Functional and Integrative Genomics, Faculdade de Ciências, Universidade de Lisboa, 1649-004 Lisbon, Portugal.
authors.forename: Rogério
authors.initials: R
authors.lastname: Tenreiro
authors.affiliation: Center for Biodiversity, Functional and Integrative Genomics, Faculdade de Ciências, Universidade de Lisboa, 1649-004 Lisbon, Portugal.
authors.forename: Sandra
authors.initials: S
authors.lastname: Chaves
authors.affiliation: Center for Ecology, Evolution and Environmental Changes, Faculdade de Ciências, Universidade de Lisboa, 1649-004 Lisbon, Portugal.
authors.forename: Ana I
authors.initials: AI
authors.lastname: Meleiro
authors.affiliation: Physiology and Biochemistry of Microorganisms Lab., Center of Biosciences and Biotechnology, Universidade Estadual do Norte Fluminense Darcy Ribeiro (UENF), Rio de Janeiro, 28013-620 Brazil.
authors.forename: Sávio B
authors.initials: SB
authors.lastname: de Souza
authors.affiliation: Center for Ecology, Evolution and Environmental Changes, Faculdade de Ciências, Universidade de Lisboa, 1649-004 Lisbon, Portugal.
authors.forename: Teresa
authors.initials: T
authors.lastname: Dias
authors.affiliation: Center for Ecology, Evolution and Environmental Changes, Faculdade de Ciências, Universidade de Lisboa, 1649-004 Lisbon, Portugal.
authors.forename: Cristina
authors.initials: C
authors.lastname: Cruz
authors.affiliation: Physiology and Biochemistry of Microorganisms Lab., Center of Biosciences and Biotechnology, Universidade Estadual do Norte Fluminense Darcy Ribeiro (UENF), Rio de Janeiro, 28013-620 Brazil.
authors.forename: Alessandro C
authors.initials: AC
authors.lastname: Ramos
keywords: Biocontrol; Conventional farming; Fungi; Nitrogen fixation; Organic farming; Rhizosphere