Biorremediação de n-hexadecano em sedimento de manguezal.

Abstract

Contamination of environments by oil and its derivatives has been a recurring problem from the first spill accidents to the present day, mainly because it affects and harms coastal ecosystems such as mangroves, which are very ecologically important. These contaminants are highly toxic and can persist in these locations for long periods of time, and their removal can be complicated. For its decontamination, many techniques can be employed, and one of them is the bioremediation by immobilized microorganisms, which has been outstanding for its degradation efficiency, good cost-benefit, ease of application and for being environmentally appropriate. The objective of this work was to monitor the biodegradation of n-hexadecane in mangrove sediment microcosms by a consortium of two strains of hydrocarbonoclastic bacteria (Gordonia sp. HEX 5 and Micrococcus sp. HEX 6) immobilized on chitosan spheres, by means of tests. dehydrogenase activity (ADH) analysis, besides evaluating the profiles of microbial communities of this soil during the PCR-DGGE experiment. The experiment was conducted over 60 days, with reinforcement of the n-hexadecane contaminant on the 30th day. Biodegradation was assessed by measuring dehydrogenase activity. The analyzes showed that the groups that contained the immobilized consortium with hexadecane or chitosan with hexadecane had different dehydrogenase activity than basal. The group treated only with chitosan and hexadecane showed increased activity only 3 days after hexadecane recontamination on day 30, reaching an amount of 41,49 ± 9,47 µg TPF.g-1 on day 51 (T51), remaining until the end of the experiment. The groups that contained immobilized consortium (with and without surfactant) presented the highest rates of enzymatic activity, whose highest peak was given by the group containing the immobilized consortium with hexadecane, which was 86,70 ± 10,8 µg TPF.g-1. Comparisons of the profiles generated by denaturing grade electrophoresis (DGGE) showed that there was a selection of organisms in each microcosm after 60 days of experiment. The product applied in this work has relevance to the various current spill cases, besides being effective, biodegradable, safe and can be reused even after recontamination of the environment.