Assays on experimental methods for the obtention of auxotrophic mutants from xanthomonas campestris

O artigo apresenta resumo em inglês.Different methods were tried with the aim of obtaining auxotrophic mutants from the phytopathogenic bacteria Xanthomonas campestris, isolated from Brassica oleraeea. The most effective method was by combining the method of Gorini and Kaufman, (using 0,54 M sucrose to avoid the lysis of prototrophic bacteria) and the method of Lubin (by recycling the growing of the bacterial cells with penicillin. Three types of mutants were produced: a) a group of unstable mutants; b) a group of mutants with residual growth; c) a group of auxotrophic mutants requiring one of the following aminoacids: proline, tryptophane, and phenylalanine; one mutant requiring isoleucine plus valine; one mutant requiring histidine and leucine; and one mutant requiring glycine and lysine. The mutant deficient for the synthesis of glycine and lysine showed a relationship toward ornithine and citrulline, since lysine could be substituted by either one of the latter aminoacids

The effect of nystatin and amphotericin B on the induction of respiratory defficient mutants (RD) from Saccharomyces cerevisiae

O artigo apresenta resumo em inglês.Respiratory defficient mutants from Saccharomyess cerevisiae were induced by nystatin and by amphotericin B. The highest yield of mutants was obtained at the concentration of 2.7 x 10-6M for nystatin and 3.1 x 10-7M for amphotericin B. It was found out that there is a relationship between the concentration of the inducing compounds and the number of cells per ml, in regard to the yield of mutants obtained. The proper mutagenic concentrations of the inducing compounds were in the range between the lethal dosis and the ones which cause no appreciable effect in the cells

Amostras ambientais de Cryptococcus neoformans var. grubii na cidade de Santos, SP, Brasil

This study involved a total of 116 samples, 79 taken from pigeon droppings and 37 of atmospheric air taken close to accumulations of excrement. Cryptococcus neoformans var. grubii was isolated from 11 (13.9%) of these samples. Other species of Cryptococcus were also isolated from these samples, such as C. albidus (12.6%) and C. laurentii (8.9%). C. neoformans was not isolated from the air samples, though C. albidus (5.4%) was. All the strains of C. neoformans were found to belong to the A serotype (C. neoformans var. grubii). In regard to the studies with the antifungal agents 5-fluorocytosine, fluconazole, itraconazole, amphotericin B and voriconazole, by means of the microdilution method (EUCAST), we point out that one sample demonstrated resistance to fluconazole, this being especially significant because this is an environmental strain.Analisaram-se 116 amostras, sendo 79 de fezes de pombos e 37 de ar atmosférico de regiões com acúmulo de fezes. Isolou-se Cryptococcus neoformans var. neoformans de 11 (13.9%) destas amostras. Outras espécies de Cryptococcus também foram isoladas destas amostras tais como C. laurentii (8.9%) e C. albidus (12.6 %), o qual também foi isolado de amostras do ar (5.4 %). Todas as amostras de C. neoformans foram sorotipo A (C. neoformans var. grubii). Em relação à avaliação do perfil de sensibilidade às drogas antifúngicas (5-fluorocitosina, fluconazol, itraconazol, anfotericina B e voriconazol) pelo método da microdiluição (EUCAST, 2002), destacou-se a presença de uma amostra com valor de concentração inibitória mínima (CIM) elevado para fluconazol, sendo de grande significância, uma vez tratar-se de isolado ambiental