Resumo

SOLANS, Mariana  e  VOBIS, Gernot. Saprophytic actinomycetes associated to the rhizosphere and rhizoplane of Discaria trinervis. Ecol. austral [online]. 2003, vol.13, n.1, pp.97-107. ISSN 1667-782X.

A total number of 122 strains of actinomycetes were isolated from both rhizosphere and rhizoplane of the plant Discaria trinervis (Hook et Arn.) Reiche. By employing morphological criteria, the strains could be arranged into six genera: Streptomyces (54 strains), Actinoplanes (27), Micromonospora (20), Actinomadura (7), Pilimelia (4), and Streptosporangium (1), along with a category of nocardioform organisms (9). The actinomycetes population varied in number and composition according to the two different sources. Most of the strains (62.3%) were isolated from the rhizosphere, predominantly belonging to Streptomyces, Actinoplanes, Pilimelia, and nocardioforms. The remaining 37.7% derived from the rhizoplane, belonging to Streptomyces, Micomonospora, Actinomadura, and Streptosporangium. Strains of the genus Streptomyces were distributed in equal numbers in both habitats. All isolates were examined concerning their ability to degrade various biopolymers. Only 14 strains were recorded without any effect to degrade plant material. The rest of the strains could be estimated as active, in extreme cases being able to decompose up to five different substrates. A total of 68% of strains showed enzymatic activity to degrade starch, 65.6% pectin, 59% cellulose, 28.7% hemicellulose, 3.3% keratin, and 15.6% had strong affinities to use lignin as a preferable substrate.

Palavras-chave : Saprophytic actinomycetes; Enzymatic activity; Rhizosphere; Rhizoplane.

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