Biosorption of heavy metals by Talaromyces helicus: a trained fungus for copper and biphenyl detoxification

At present, it is common to observe environments with organic and inorganic pollution, defined as co-contamination. Most industrial and urban effluents releases both pollutant types, leading to a complex environmental problem, as the biota must be tolerant to both xenobiotics. T. helicus, an efficient strain to degrade biphenyl, was trained with high copper levels, and became co tolerant to cobalt, lead and cadmium when was cultured in their presence. The copper adaptation was the result of physiological mechanisms, and the activated biochemical processes conferred resistance to Cu2+ as well as to other heavy metals. Furthermore, the Cu2+ adaptation of the mycelium was also transferred to the spores, that removed twice as much copper from solution than those of the no trained parentals. Interestingly, metals combinations were less toxic than single ones, and co tolerance development indicated that the cellular mechanisms that conferred resistance were non-specific, so the micobiota isolated from co contaminated environments often exhibited resistance to more than one ions. These results emphasized the detoxification abilities of T. helicus and the adaptation to heavy metals and biarylic compounds. This data is significant for the environmental biotechnology, suggesting that such tolerance and co tolerance could be acquired in natural environments. So a simple bioremediation strategy could enhance the detoxification of these polluted areas, as the degrader organisms could be present.

Chlorinated biphenyl degradation by wild yeasts pre-cultured in biphasic systems

Environmental biotechnology has developed as an offshoot from sanitary engineering, and only recently the biological component of the ecosystems had been recognized as relevant when bioremediation strategies must be chosen to solve environmental problems. Yeasts were isolated on 2,4-dichlorobiphenyl, 2,3',4- and 2,4',5-trichlorobiphenyl, poorly soluble compounds in water, as carbon sources. Debaryomyces castelli, Debaryomyces maramus and Dipodascus aggregatus composed the mixed culture and represented 72 percent of the isolates; their degradation potential were studied in biphasic and monophasic systems. The biphasic cultures were obtained with phenol as the organic phase and MSM as the aqueous ones, the monophasic medium only with MSM. Both cultures were supplied with 50, 100, 150 and 200 ppm DCB, TCB-3' and TCB-4' as substrate. The growth rates varied with the dispersion degree, agitation rates and cell adhesion to the organic phase. The water-phenolic system improved yeasts selection in pollutant presence with low water solubilities, indeed, the adaptation and degradation were more slowly in the monophasic aqueous medium. Bioremediation is based on the presence of efficient microbial populations and pollutant availability; the tested yeasts and the organic-water system assayed put forward the possibility that hydrophobic substrates could be mineralized in natural habitats by wild yeast consortium.