AvaliaÃÃo sobre a biodegradaÃÃo de paclobutrazol utilizando culturas mistas de bactÃrias

AUTOR(ES)

Fernanda LeitÃo Vaz

DATA DE PUBLICAÇÃO

2006

RESUMO

Paclobutrazol (PBZ) is a regulator of vegetal growth that remains active in the soil and can affect the growth and the development of subsequent cultures. The aim of this work was to investigate the biodegradation of paclobutrazol by soil native bacteria of two locations of the northeastern region of Brazil, Mandacaru and Bebedouro, with cultures of mango, with and without previous PBZ utilization. The bacteria were isolated by enrichment and partially characterized. Biodegradation experiments were carried out using mixed cultures of Pseudomonas spp., according to the isolation location, in mineral broth with only PBZ or with addition of glycerol or glucose as carbon sources. Experiments where also carried out with the addition of Streptomyces and Rhodococcus strains. Shake flasks were incubated at 30 ÂC and 200 rpm, during 30 days, and samples were taken daily in predefined intervals. Quantification of growth and biodegradation were made by spectrophotometry at 420 and 221 nm, respectively. In experiments using PBZ as the sole carbon source, growth was significant and biodegradation reached a maximum value of 47 % in 20 days when a mixed culture of Pseudomonas (MS), isolated in the region of Mandacaru without previous PBZ application, was used. When Streptomyces and Rhodococcus strains were added to mixed culture MS, no growth was observed. In experiments using PBZ and glucose as carbon sources, growth of mixed culture MS was considerably higher, not being, however, verified biodegradation of PBZ. When PBZ and glycerol were used, growth of mixed culture MS was lower, but still higher than in the experiments with PBZ as the sole carbon source. Production of biosurfactant in experiments using PBZ and glycerol as carbon sources was quantified as 0,2 g/L, while in the experiments with PBZ as the sole carbon source production was not verified

ASSUNTO(S)

agroquÃmicos biorremediaÃÃo quimica dos produtos naturais pseudomonas sp. poluentes biodegradaÃÃo culturas mistas paclobutrazol

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