Biorremediação de sedimentos de manguezal contaminados com n-hexadecano por consórcio de actinobactérias imobilizado em esferas de quitosana

Abstract

Mangrove areas suffer from the direct impact of deforestation for aquiculture and/or urban development, as well as the impacts of pollution. Among the remediation technologies, bioremediation stands out as one of the most suitable for the recovery of contaminated mangrove areas, due to the complexity of this ecosystem. Bioremediation consists of a set of processes in which living organisms are employed, typically plants or microorganisms, aiming to remove or mitigate the effect of environmental pollutants. This study evaluated the capability of seven bacterial strains, previously isolated from mangrove sediment contaminated with nhexadecane, to degrade the aforementioned pollutant in sediment microcosms inoculated with those selected bacterial strains in suspension, free form, or as a consortium immobilized in chitosan beads. Was also evaluated the effects of native micro biota and the biodegradability of the chitosan beads in treatments. Biodegradation potential of the bacterial consortium was evaluated by monitoring the desidrogenasic activity (DHA), estimated by measurements of formazan concentration. Among the seven tested strains, 2 actinobacteria, Gordonia HEXBA05 and Micrococcus HEXBA06, have excelled and were gathered in a consortium CHB56 to be tested in sterilized and unsterilized sediment, both in free form and immobilized in chitosan beads. The consortium, immobilized at a concentration of 106 CFU/g of chitosan beads and inoculated in unsterilized mangrove sediment microcosms contaminated with 10 mg/g of n-hexadecane showed significantly different desidrogenasic activity from the control, demonstrating the capacity to metabolize the pollutant of the consortium. The chitosan beads were completely biodegraded by the native micro biota of mangrove sediment in 12 days. The results of this study point to the fact that the consortium CHB56 immobilized in chitosan beads represents a new option of bioremediation technology, and can be applied in mangroves contaminated with n-hexadecane, an alkane commonly found in oil spill areas, with the advantages of being an ecologically safe technology of easy application and handling.