Sunday, April 29, 2007

Degradation of crude oil by Yarrowia lipolytica

Roberta R. Ribeiro1, Cláudia V. Medeiros1, Renata V. Nascimento1, Luis M. B. Filipe2, Priscilla F.F. Amaral1, João A.P. Coutinho2, and Maria Alice Z. Coelho1. (1) Biochemical Engineering Department, Universidade Federal do Rio de Janeiro, CT, Bl. E, Cidade Universitária, 21949-900, Rio de janeiro, Brazil, (2) Chemical Department, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193, Aveiro, Portugal

Oil spills pose a great hazard for terrestrial and marine ecosystems. The total influx of oil into the sea is estimated to be approximately 5,2 million tones, and in productive areas it is almost unavoidable. Biodegradation is a microbial process whereby the petroleum is used as an organic carbon source, resulting in the breakdown of petroleum components to compounds of lower molecular weight or the transformation of petroleum components to more polar compounds of a carbon number equal to the parent compound. Naturally occurring microorganisms in a contaminated site are already biodegrading the pollutant. Addition of microorganisms in these sites may enhance contaminant removal. In the present work, the degrading potential of an aerobic alkane assimilating yeast, Yarrowia lipolytica, is evaluated. An experimental design was performed varying the initial cell concentration (0.1 and 1.0 mg/ml), the initial petroleum concentration (0.1 and 1.0% (v/v)), the agitation speed (70 and 160 rpm) and glucose concentration (0 and 1.0 g/l). All experiments were performed in 250 ml erlermeyer flasks with 100 ml of inorganic medium. The results shows the microorganism great potential to degrade crude oil. The agitation speed and the presence of glucose were statistically important factors.