Diversidad y estabilidad en comunidades microbianas destinadas a la oxidación de efluentes sulfurados

Very often, technologies for the treatment of contaminated effluents rely heavily on pure cultures of a single species isolated or even engineered for high detoxifing activity. Biological treatments based on this principle are usually hampered by the unability of the selected organism to survive and proliferate under working conditions. This is mainly consequence of a strict dependance of pure culture systems on accurate control of environmental conditions.Slight departures from the optium conditions can result in a dramatic decrease of the detoxifying activity and even in the complete inactivation of the culture. We put forward the hypothesis that detoxifying systems based on complex microbial communities selected by a minimum set of well chosen process conditions and allowed to develop until reaching a steady state, will have higher stability in the face of environmental perturbations. We expect microbial communities to be more rugged and to requiere e much looser control than pure cultures therefore resulting in less expensivew and more durable designs. To best this hypothesis we take as a model the oxidation of sulfide-conatining efffluents and propose to carry out a study in foursteps:1)Set up of a fixed-biomass bioreactor under conditions wich allow the establishment of a sulfideoxidizing community.2) Characterization of the microbial community in terms of oxidizing activity and of taxonomic diversity using state of art techniques based on the analysis of 16S rRNA. 3)Introaduction of discrete perturbations in some of the envionmental parameters (light, temperature, nutrients, organic matter) and analysis of the effects on the activit and on the taxonomic structure of the community.4) Comparison of the results with similar results obtained in a bioreactor colonized with a pure culture of a sulfur oxidizer undergoing the same challenges.