Monoaromatic hydrocarbon biodegradation by Pseudomonas strains

CARLA DI MARTINO; PAULA M. TRIBELLI; NANCY I. LOPEZ; LAURA J. RAIGER IUSTMAN

Potrero de los Funes, San Luis

Congreso; XLVII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2011

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Monoaromatics hydrocarbons like benzene, toluene and xylene (BTX) are toxic compounds present in oil contaminated sites. Pseudomonas spp. KA-08 (KA) and KB-08 (KB) were isolated from activated sludge in our lab using kerosene as sole carbon source. As alkane dehydrogenase was not found in these strains, we proposed that BTX fraction in kerosene could support their growth. The aim of this work was to analyze degradation of BTX compounds by Pseudomonas spp. KA and KB. Both strains were able to grow with benzene, toluene and xylene as sole carbon source when the concentrations were 0,1%, 0.1% and 5% v/v respectively. KA was also able to grow with xylene at high concentrations (up to 90%). Xylene degradation was assayed qualitatively using an adaptation of the Microtox method by testing luminescence of Vibrio fischerii. Detection of genes involved in BTX degradation was analyzed by PCR amplification. Fragments corresponding to catechol dioxygenase (xylE) and xylene monooxygenase (xylA) genes were detected in both strains, while an aromatic dioxygenase (todC1) gene was present only in KA. Capability to produce biosurfactants in cultures with xylene 1% v/v was assayed by analyzing emulsifying activity (EA). EA was 17% and 22% in KB and KA, respectively. Our results suggest that these strains showed appropriated characteristics to be considered as monoaromatics bioremediation agents.