Efficacy of fungal decolorization of a mixture of dyes belonging to different classes

Dyes are the most difficult constituents to remove by conventional biological wastewater treatment. Colored wastewater is mainly eliminated by physical and chemical procedures, which are very expensive and have drawbacks. Therefore, the advantage of using biological processes, such as the biotransformation of dyes, is that they may lead to complete mineralization or formation of less toxic products. To prove the possibility of using fungal processes for decolorization and other applications, the analysis of the toxicity of the processes' products is required. The decolorization of the mixture of two dyes from different classes - triphenylmethane brilliant green and azo Evans blue (GB - total concentration 0.08 g/L, proportion 1:1 w/w) - by Pleurotus ostreatus (BWPH and MB), Gloeophyllum odoratum (DCa), RWP17 (Polyporus picipes) and Fusarium oxysporum (G1) was studied. Zootoxicity (Daphnia magna) and phytotoxicity (Lemna minor) changes were estimated at the end of the experiment. The mixture of dyes was significantly removed by all the strains that were tested with 96 h of experimental time. However, differences among strains from the same species (P. ostreatus) were noted. Shaking improved the efficacy and rate of the dye removal. In static samples, the removal of the mixture reached more than 51.9% and in shaken samples, more than 79.2%. Tests using the dead biomass of the fungi only adsorbed up to 37% of the dye mixture (strain BWPH), which suggests that the process with the living biomass involves the biotransformation of the dyes. The best results were reached for the MB strain, which removed 90% of the tested mixture under shaking conditions. Regardless of the efficacy of the dye removal, toxicity decreased from class V to class III in tests with D. magna. Tests with L. minor control samples were classified as class IV, and samples with certain strains were non-toxic. The highest phytotoxicity decrease was noted in shaken samples where the elimination of dye mixture was the best.

Multiplicación en sistemas de inmersión temporal y enraizamiento ex vitro de ocumo blanco (Xanthosoma sagittifolium (L) Schott) / Multiplication in temporary immersion systems and ex vitro rooting of white cocoyam (Xanthosoma sagittifolium (L) Schott)

El ocumo (Xanthosoma sagittifollium (L.) Schott) es una Arácea cultivada en países tropicales debido al valor nutritivo de sus cormos. La principal limitante para su cultivo es la carencia de semilla de calidad, por esta razón se planteó evaluar la multiplicación de brotes de ocumo blanco en sistemas de inmersión temporal, y el enraizamiento ex vitro de los mismos, para lo cual se estudió el tiempo y la frecuencia de inmersión, y la densidad de explantes sobre la proliferación de los brotes. Asimismo, el efecto del ácido indolacético (AIA) y ácido indolbutírico (AIB) sobre el enraizamiento ex vitro de brotes. De acuerdo con los resultados obtenidos, la mayor eficiencia en la proliferación de brotes se obtuvo utilizando el sistema de inmersión temporal del tipo RITA®, con una frecuencia y tiempo de inmersión de 6 veces/día y 5 min, respectivamente, y una densidad de 9 explantes/RITA®. En el enraizamiento ex vitro se determinó que bajo las condiciones de cultivo empleadas no es necesario el uso de auxinas. Se concluye que es posible la multiplicación eficiente de ocumo blanco en sistemas de inmersión temporal, y realizar el enraizamiento ex vitro sin el uso de auxinas.

The white cocoyam (Xanthosoma sagittifollium (L.) Schott), is an Arácea cultivated in tropical countries, due to the nutritional value of its corms. The main limiting factor for cultivation is the lack of healthy seed, by this reason be outlined to evaluate the multiplication of shoots of white cocoyam in temporary immersion systems and the ex vitro rooting of the same. For that which, itself study, the time and frequency of immersion and the density of explants on the proliferation of the shoots. As well as, the effect of the indole acetic acid (IAA) and indole butyric acid (IBA) on ex vitro rooting the shoots was studied. According to the results obtained, the greater efficiency in the proliferation of shoots was obtained utilizing the temporary immersion system of the type RITA®, with a frequency and time of immersion of 6 times/day and 5 min, respectively and a density of 9 explantes/RITA®. In the ex vitro rooting was determined that under the conditions of employed cultivation is not necessary the use of auxins. It is concluded that is possible the efficient multiplication of white cocoyam in temporary immersion systems and to carry out the ex vitro rooting without the use of auxins.

Density-dependent reproductive and vegetative allocation in the aquatic plant Pistia stratiotes (Araceae)

Pistia stratiotes is an aquatic macrophyte that grows in temporary-ponds in the southern Pantanal, Brazil. It reproduces both sexually and asexually and is usually observed forming dense mats on the water surface, a condition favored by the plant’s vegetative reproduction coupled with an ability for rapid growth. In this study we examined the effect of densely crowded conditions on the production of reproductive and vegetative structures. In addition, we verified whether there is a trade-off between clonal growth and investment in sexual reproductive structures, and whether there is an allocation pattern with plant size. Individual plant biomass and the number of the rosettes producing sexual reproductive structures and vegetative growth structures both increased with density. Increase in plant size resulted in increased proportional allocation to sexual reproductive structures and vegetative growth structures. Allocation of biomass to reproduction did not occur at the expense of clonal growth. Thus, the density response appears as a increase of rosettes producing sexual reproductive structures and vegetative growth structures. Therefore, long leaves and stolons may be adaptive under densely crowded conditions where competition for light is intense. An important aspect in the study of trade-offs is the size-dependency of the allocation patterns .Usually, larger plants produce more biomass. Therefore, larger plants can allocate more biomass to both vegetative and sexual reproduction than smaller plants and thus show a positive correlation between both traits rather than the expected negative one

Pistias strariotes es una macrófita acuática que crece en charcas estacionales en el Pantanal sureño de Brasil. Se reproduce tanto sexual como asexualmente y se obsrva generalmente que forma densas parches sobre la superficie del agua, una condicion que favorecida por la reproduccion vegetativa de la planta junto con una habilidad para el rapido crecimiento. En este estudio se examinó el efecto de las condiciones densamente aglomeradas sobre las estructuras reproducctivas y vegetativas. En adicion, se verificó hasta donde hay un intercambio entre el crecimiento clonal y la inversión en estructuras reproductivas, y hasta donde hay un patrón de tranlocación con el crecimiento de la planta. La biomasa individual de las plantas y el número de rosetas productoras de estructuras reproductivas y estructuras de crecimiento vegetativo se incrementan con la densidad. El incremento en el tamaño de las plantas resultó en un incremento proporcional de la asignación hacia estructuras reproductivas y estructuras de crecimiento vegetativo. La asignación de biomasa hacia reproducción no ocurrió a expensas del crecimiento clonal. Así, la respuesta a la densidad parece como un incremento en la producción de rosetas que producen estructuras reproductivas y de crecimiento vegetativo. Por lo tanto, las hojas largas y estolones pueden ser adaptativas bajo condiciones de densamente aglomeradas dond la competencia por la luz es intensa. Un aspecto importante en el estudio de intercambio son los patrones asignación dependientes de la densidad. Usualmente, las plantas más grandes producen más biomasa. por lo tanto, las plantas más grandes pueden asignar más biomasa hacia la reproducción vegetativa y sexual que las plantas pequeñas y así mostraron una correlación positiva entre ambos caracteres

Plant regeneration of Anthurium andreanum cv Rubrun

To establish an efficient regeneration system for Anthurium andreanum cv Rubrun, seeds from plant spadixes were germinated on a medium supplemented with 2.2 muM BA. After 2 weeks, 74 percent of the seeds germinated and four weeks later, micro-cuttings from these plantlets were subcultured on a medium containing 4.4 muM BA and 0.05 muM NAA. On average, 3.6 shoots per explant were obtained. Four weeks old in vitro plants from germinated seeds and the plantlets obtained from micro-cuttings, showed callus proliferation at the stem base. These tissues were subcultured on a medium supplemented with 8.9 muM BA and 2.7 muM NAA. After 6 weeks of culture, about 43.8 plantlets per square cm of callus were obtained. Anatomical studies showed the organogenic nature of these calli. Anthurium andreanum plants regenerated by organogenesis were transferred to pots and a rate of 80 percent of plant acclimatization was obtained.