Removal of dyes by immobilization of Trametes versicolor in a solid-state micro-fermentation system.

A novel bioreactor system (low cost and easily scaled-up) is presented for dye decolorization applying filamentous fungi. In this two-phase bioreactor, dyes were decolorized at 28°C in a first phase by immobilized fungi in spherical cartridges prepared with a high-density plastic polyethylene mesh and filled with wheat bran as substrate for growth. In a second phase the capacity of the ligninolytic enzymes (laccase and Mn-peroxidase) present in the extracellular extracts from the solid residues was exploited for decolorization at 50°C. Each sphere behaved as a small-scale bioreactor for cell-culture. This system allowed the decoupling of growth (sterile condition) and decolorization (non-sterile condition) stages. The ability to decolorize the azo dye xylidine and the triphenylmethane Malachite Green by two Argentinean strains of Trametes versicolor was evaluated. The highest decolorization rates were displayed by T. versicolor BAFC 2234. When both dyes were applied together in the bioreactor, after a first phase (100min) 73.5% of Malachite Green and 40% of xylidine decolorization was attained, while at the end of the second phase (240min) a 97% and 52% decolorization was observed. Laccase activity was detected in the decolorized solution, but no Mn-peroxidase activity. The easy change of the cartridges allows the continuous use of the bioreactor in the non-sterile decolorization of dye-containing effluents.

[Cellulolytic activity of coprophilic fungi]. / Actividad celulolítica de hongos coprófilos.

Fourteen isolates, members of the Ascobolaceae family, representing two widespread genera, Ascobolus and Saccobolus, were obtained from dung of herbivorous animals. All the isolates were capable of growing and producing clearing zones in CMC agar media. The species of Ascobolus gave larger clearing zones than the species of Saccobolus. S. verrucisporus and S. longevisporus were the most cellulolytic species in this genera while A. bistisii was the most cellulolytic among all the species tested. The results obtained showed that more than one method of screening must be employed to analyse the cellulolytic ability of different species.