Endophytic bacteria from three arboreal species native to the Amazon (Carapa guianenses, Ceiba pentandra, and Swietenia macrophylla), were isolated and identified, through partial sequencing of the 16S rRNA encoding gene. From these, 16 isolates were obtained, although, when compared to sequences deposited in GenBank, only seven had produced identifiable fragments. Bacillus, Pantoea and two non-culturable samples were identified. Results obtained through sequence analysis revealed low genetic diversity across the isolates, even when analyzing different species and plant structures. This is the first report concerning the isolation and identification of endophytic bacteria in these plant species.

The electrophoretic karyotype of the dermatophyte Trichophyton rubrum was established using contour-clamped homogeneous electric field (CHEF) gel electrophoresis. Five chromosomal bands of approximately 3.0 to 5.8 megabase pairs (Mbp) each were observed and together indicated that 22.05 Mbp of the total genome are organized as chromosomal macromolecules. In addition to establishing the number and size of T. rubrum chromosomes, these results open perspectives for the construction of chromosome-specific libraries and for the physical mapping of genes of interest, thus permitting future gene linkage studies in this pathogen. A detailed understanding of the karyotype and genomic organization of T. rubrum should contribute to further genetic, taxonomic and epidemiological studies of this dermatophyte.

Nesta comunicação nós mostramos que o crescimento do isolado H6 do dermatófito T. rubrum em meio não tamponado e sob condição saturante de fosfato, é dependente do pH inicial de cultivo, com um ótimo aparente em pH 4,0. Além disto, independente do pH inicial, o pH do meio se altera durante o cultivo alcançando valores que variam de 8,3 a 8,9. Verificou-se também que este isolado sintetiza e secreta quase os mesmos níveis de fosfatase alcalina, com um ótimo de atividade aparente entre os valores de pH 9,0 e 10,0, independentemente da concentração de fosfato no meio. Também mostramos que essa fosfatase alcalina é inibida por EDTA e ativada por Mg2+. Por outro lado, o nível dessa enzima retida no micélio cultivado em meio tamponado em pH 5,0-5,2 é baixo, sugerindo que ela seja codificada por um gene alcalino, isto é, um gene responsivo à sinalização pelo pH ambiente.

In this communication, we show that the growth of isolate H6 of the dermatophyte Trichophyton rubrum on non-buffered medium and under saturating phosphate conditions is dependent on the initial growth pH, with an apparent optimum at pH 4.0. In addition, irrespective of the initial growth pH, the pH of the medium alteredduring cultivation reaching values that ranged from 8.3 to 8.9. Furthermore, this isolate synthesized and secreted almost the same levels of an alkaline phosphatase with an apparent optimum pH ranging from 9.0 to 10.0 when grown on both low- and high-phosphate medium. Also, this alkaline phosphatase is activated by Mg2+ and is EDTA-sensitive. On the other hand, the very low levels of the enzyme retained by the mycelium grown on buffered medium at pH 5.0-5.2 suggest that this enzyme is encoded by an alkaline gene, i.e., a gene responsive to ambient pH signaling.