Although new studies describe the use of PGPR (Plant Growth-Promoting Rhizobacteria) in Brazil, they rarely evaluate the natural existence of these bacterial species in the soil. The objective of this study was to evaluate PGPR in two samples under different use types, one with native forest and the other with eucalyptus, through construction and sequencing of a metagenomic DNA library. Using specific probes from the internally transcribed region of 16S-23S rRNA genes, fragments of PCR products were inserted into the vector […]

Anthropogenic disturbances have resulted in an increased threat of extinction of many native orchid taxa in Brazil’s Atlantic rain forest. In nature, orchids utilize mycorrhizal fungi to initiate seed germination and seedling development, at least in the early stages of their life cycle. Mycorrhizal fungi associated with the roots of orchids have thus been isolated, characterized and stored as important resources for a future conservation program of orchid species through symbiotic seed germination. Three mycorrhizal Rhizoctonia-like fungi were isolated from […]

Symbiotic in vitro seed germination and protocorm development of Oncidium flexuosum is described for the first time. O. flexuosum seeds were inoculated with ten mycorrhizal isolates, originally obtained from the mycorrhiza of ten neotropical Brazilian orchid species, including O. flexuosum. One of the isolates belongs to Epulorhiza repens, two to Epulorhiza epiphytica, six to Ceratorhiza spp., and one to Rhizoctonia sp. Seeds inoculated with the M2 isolate of Ceratorhiza sp., originally isolated from the root system of wild O. flexuosum, […]

Arbuscular mycorrhiza can be important for plant nutrition in acid and low fertility soils such as those of the Amazon. The present study evaluated the mycorrhizal colonization by native arbuscular mycorrhizal fungi (AMF) and nutrient concentrations of cupuassu and guarana leaves in an agroforestry system in Manaus, Amazonas State, Brazil. Ten plants of each species were selected, of which the roots, soil and leaves were sampled during the rainy and dry seasons. Guarana and cupuassu trees presented higher levels of […]

Azospirillum amazonense is a widespread N2 fixing bacterium, occurring mainly in association with grasses and palm trees roots. Aiming to study its occurrence in species of other families not yet studied and the efficiency of media. Fam and LGI for its detection, these were used for rhizosphere soil counting or for enrichment cultures of rhizosphere soil, ecto and endorhizosphere. A. amazonense was detected in rhizosphere soil, ecto and endorhizosphere of many species belonging to monocotyledons, including Orchidaceae and dicotyledons with. […]

The arbuscular mycorrhizal fungi (AMF) are ubiquitous establishing symbiosis with a large number of plants in spite of soil contamination with heavy metals.This study aimed to evaluate AMF occurrence and diversity in soils of four locations cultivated with grass species and contaminated with heavy metals as a result of Zn extraction and industrialization. AMFs were found in all locations, with species predominance being affected by heavy metal concentration in soil. Twenty one species were identified, belonging to the following genus: […]

The use of phosphate-solubilizing bacteria can be a low-cost alternative to agroforestry systems in the Amazônia, where prices, transport, and producers’ low buying capacity make the use of soluble fertilizers difficult. On soils without a cultivation past, phosphates are combined mainly to Al, while on previously limed and cultivated soils, these phosphates are combined with Ca, limiting their use by plants. There is little information on phosphate-solubilizing bacteria (BSF) in the Amazon; thus, further studies are needed. The first step […]