RESUMO
Global industrialization and natural resources extraction have left cocktails of environmental pollutants. Thus, this work focuses on developing a defined actinobacteria consortium able to restore systems co-contaminated with pollutants occurring in Argentinian environments. In this context, five actinobacteria were tested in solid medium to evaluate antagonistic interactions and tolerance against lindane (LIN), Reactive Black B-V (RBV), phenanthrene (Ph) and Cr(VI). The strains showed absence of antagonism, and most of them tolerated the presence of individual pollutants and their mixtures, except Micromonospora sp. A10. Thus, a quadruple consortium constituted by Streptomyces sp. A5, M7, MC1, and Amycolatopsis tucumanensis DSM 45259T, was tested in liquid systems with individual contaminants. The best microbial growth was observed in the presence of RBV and the lowest on Cr(VI). Removals detected were 83.3%, 65.0% and 52.4% for Ph, RBV and LIN, respectively, with absence of Cr(VI) dissipation. Consequently, the consortium performance was tested against the organic mixture, and a microbial growth similar to the biotic control and a LIN removal increase (61.2%) were observed. Moreover, the four actinobacteria of the consortium survived the mixture bioremediation process. These results demonstrate the potential of the defined actinobacteria consortium as a tool to restore environments co-contaminated with organic pollutants.
Assuntos
Actinobacteria , Poluentes Ambientais , Poluentes do Solo , Actinobacteria/genética , Biodegradação Ambiental , Poluentes do Solo/análise , Hexaclorocicloexano , CromoRESUMO
The use of living actinobacteria biomass to clean up contaminated soils is an attractive biotechnology approach. However, biomass generation from cheap feedstock is the first step to ensure process sustainability. The present work reports the ability of four actinobacteria, Streptomyces sp. M7, MC1, A5, and Amycolatopsis tucumanensis, to generate biomass from sugarcane vinasse. Optimal vinasse concentration to obtain the required biomass (more than 0.4 g L-1) was 20% for all strains, either grown individually or as mixed cultures. However, the biomass fraction recovered from first vinasse was discarded as it retained trace metals present in the effluent. Fractions recovered from three consecutive cycles of vinasse re-use obtained by mixing equal amounts of biomass from single cultures or produced as a mixed culture were evaluated to clean up contaminated soil with lindane and chromium. In all cases, the decrease in pesticide was about 50% after 14 d of incubation. However, chromium removal was statistically different depending on the preparation methodology of the inoculum. While the combined actinobacteria biomass recovered from their respective single cultures removed about 85% of the chromium, the mixed culture biomass removed more than 95%. At the end of the reused vinasse cycle, the mixed culture removed more than 70% of the biological oxygen demand suggesting a proportional reduction in the effluent toxicity. These results represent the first integral approach to address a problematic of multiple contaminations, concerning pesticides, heavy metals and a regionally important effluent like vinasse.
Assuntos
Actinobacteria/metabolismo , Biomassa , Recuperação e Remediação Ambiental/métodos , Saccharum/microbiologia , Actinobacteria/crescimento & desenvolvimento , Análise da Demanda Biológica de Oxigênio , Cromo/isolamento & purificação , Poluição Ambiental/prevenção & controle , Hexaclorocicloexano/isolamento & purificação , Praguicidas , Solo/química , Streptomyces/metabolismoRESUMO
Chlordane bioremediation using actinobacteria mixed culture is an attractive clean-up technique. Their ability to produce bioemulsifiers could increase the bioavailability of this pesticide. In order to select a defined actinobacteria mixed culture for chlordane remediation, compatibility assays were performed among six Streptomyces strains. The strains did not show growth inhibition, and they were assayed for chlordane removal, either as pure or as mixed cultures. In pure cultures, all of the strains showed specific dechlorination activity (1.42-24.20 EU mg(-1)) and chlordane removal abilities (91.3-95.5%). The specific dechlorination activity was mainly improved with cultures of three or four microorganisms. The mixed culture consisting of Streptomyces sp. A2-A5-A13 was selected. Their ability to produce bioemulsifiers in the presence of glucose or chlordane was tested, but no significant differences were observed (p > 0.05). However, the stability of the emulsions formed was linked to the carbon source used. Only in chlordane presence the emulsions retained 100% of their initial height. Finally, the selected consortium showed a high degree of sporulation in the pesticide presence. This is the first study on the effects that chlordane exerts on microbe morphology and emulsifier production for a defined mixed culture of Streptomyces with ability to remediate the pesticide.