Population densities and genetic diversity of actinomycetes associated to the rhizosphere of Theobroma cacao

Brazilian Journal of Microbiology

Tâmara R. Barreto¹  Augusto C.m. Da Silva¹  Ana Cristina F. Soares¹  Jorge T. De Souza¹ 

[1] ,Universidade Federal do Recôncavo da Bahia Campus Universitário de Cruz das Almas Cruz das Almas BA ,Brasil

关键词: cacao;    rpoB sequence analyses;    Streptomyces spp;    cacau;    análises de seqüências do gene rpoB;    Streptomyces spp;   

DOI  :  10.1590/S1517-83822008000300010

来源: SciELO

【 摘 要 】

In spite of the acknowledged importance of growth-promoting bacteria, only a reduced number of studies were conducted with these microorganisms on Theobroma cacao. The objectives of this work were to study the population densities and genetic diversity of actinomycetes associated with the rhizosphere of cacao as a first step in their application in plant growth promotion and biological control. The populations densities of actinomycetes in soil and cacao roots were similar, with mean values of 1,0 x 10(6) CFU/g and 9,6 x 10(5) CFU/g, respectively. All isolates selected and used in this study were identified through sequencing analyses of a fragment of the rpoB gene that encodes the β-subunit of the RNA polymerase as species of the genus Streptomyces. In vitro cellulolytic, xilanolytic and chitinolytic activity, indolacetic acid production and phosphate solubilization activities were observed in most of the isolates tested. The data obtained in this study demonstrate that actinomycetes account for a higher percentage of the total population of culturable bacteria in soil than on cacao roots. Additionally, actinomycetes from the cacao rhizosphere are genetically diverse and have potential applications as agents of growth promotion.

【 授权许可】

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