Biodegradabilidade de n-Hexadecano por bactÃrias livres e imobilizadas em quitosana

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

Petroleum and its derivatives are introduced in ecosystems through leaking in reservoirs or by activities related with the extration, transportation, storage, processing, manipulation and disposal. In general these compounds are harmful to the health of the organisms, being able to cause serious environmental damages. In front of this problem there is an increasing interest in the development of more efficient methods for removal of these pollutants from the environment. The biorremediation techniques offers new possibilities to increase the degradation of pollutants and the use of immobilized microorganisms appears as an advantageous alternative to recover areas polluted by oily sources, as well as improving the efficiency of the biological process with highly recalcitrant compounds. n-Hexadecane is the major component of the Diesel oil and is frequently used by a model compound of biodegradation of long chain hydrocarbons. The aim of this work was to evaluate the biodegradation of the n-Hexadecane by bacterial strains of the collection of microorganisms of the Antibiotic Department of the UFPE. Specifically, it was intended to select strains with a higher potential to degrade n-Hexadecane, identify them and compare the efficiency of the biodegradation using free and chitosan immobilized cells, aiming the development of product for use in biorremediation of wastewater polluted with long chain aliphatic hydrocarbons. Initially, 41 bacterial strains were tested, being 40 from the vicinity of Suape port in Pernambuco, and one strain from a contaminated flask of n-Hexadecane. On the preliminary studies of two strains with the highest potential to degrade n-Hexadecane were selected, they were identified as Bacillus pumilus (Gram-positive) and Ochrobactrum anthropi (Gramnegative). These two strains were submitted to physiological studies, biochemistry characterization and resistance tests to the physical and chemical factors and antibiotics. The selected strains had better grown in concentrations of 1-5 % of n-Hexadecane, although they have been capable to grow in even 15 % of this hydrocarbon. These bacteria had not demonstrated adhesion to the oily phase (1-20 %) and they produced emulsification above of 50 %. However only B. pumilus presented hemolytic activity, that is indicative of the biosurfactant production. None of the selected strains produced chitosanase and only B. pumilus presented resistance to chitosan solutions (DG 78%) up to 4 %, being select to be immobilized in this support. Moreover, B. pumilus presented desirable characteristics for environmental applications, such as: resistance to wide pH range (5-11), temperature (16-50 oC), concentration of NaCl (10 %), irradiation UV (8 minutes) and sensitivity a lot of antibiotics. This results show a degradation with free and immobilized cells in chitosan of 98,4 % and 90,8 %, respectively. The ultraestrutural was evaluated by scanning electron microscopy. The set of results support the hypothesis that B. pumilus is a potential candidate for use in bioremediation of contaminated environmental with petroleum by free or chitosan immobilized cells

ASSUNTO(S)

petrÃleo ecologia poluentes do ambiente petroderivados vazamentos em reservatÃrios

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