Imobilização de consórcios de bactérias degradadoras de petróleo extraídas da rizosfera de plantas fitorremediadoras

Abstract

Petroleum is one of the most important sources of world energy, but is also one of the aggravating causes of environmental pollution, because accidents such as spills, leaks in pipes and inadequate waste disposal are common, where the oil comes into contact with the environment, which may persist for long periods. Thus, the development of treatment methods is necessary, among which stands out bioremediation. This is an efficient and low cost method, characterized by the use of microorganisms to degrade contaminants in less environmentally harmful compounds. To optimize this process, these microorganisms may be combined, yielding consortia with the ability to completely degrade petroleum waste. Moreover, these consortia may be immobilized in order to maintain cell viability and protection of the microorganisms. In this sense, the objective was to develop microspheres from the immobilization of five bacterial consortia extracted from the rhizosphere of phytoremediator plants for petroleum degradation. Seven bacteria, Bacillus sp.1 , Bacillus sp.2 , Stenotrophomonas sp., Bacillus sp.3 , Microbacterium sp., Bacillus sp.4 and Bacillus sp.5 , were analyzed for petroleum degradation potential through individual tests in reactors along different times, 0, 24, 48 and 72 hours, and parameters such as pH, temperature, dissolved oxygen, conductivity, biomass density and biosurfactant production were measured. Besides was analyzed the hydrocarbon degradation by Gas Chromatography (GC). Then, through the morphological and physiological characteristics of these bacteria, the consortia were defined. For each of them, bacterial biomass was produced in a bioreactor, that was used for obtaining microspheres from the immobilization in alginate and chitosan matrix. The results indicate that these bacteria, producers of biosurfactant, are promising for petroleum degradation. By GC, the maximum rates of degradation were about 83% in 24 hours and 94% in 48 hours. It was found, in relation to the consortium, that the growth of a microorganism did not affect the growth of the other, indicating microbial joint action through metabolic complementarity, for hydrocarbon degradation. It should be noted that the product obtained by the immobilization of these consortia, has uniform size and strength to maintain the spherical shape and after the lyophilization process, there was high cell viability (about 74%). The microspheres can be a biotechnological innovation allowing optimization of the bioremediation process for the treatment of petroleum contaminated environments.