Analysis of 2,4-dinitrotoluene biodegradation by a genetically modified Pseudomonas fluorescens strain

MONTI MARIELA R.; SMANIA ANDREA. M.; ARGARAÑA CARLOS E.

Bariloche-Argentina

Congreso; XXXIX Reunión Anual de SAIB; 2003

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

The objective of our work is to generate an innocuous bacterial strain able to mineralize 2,4-DNT, a known priority environmental pollutant. We previously shown (SAIB, 2001) that a P. fluorescens strain modified by chromosomal insertion of genes encoding the upper 2,4-DNT biodegradative pathway present in the pathogen Burkholderia cepacia was able to efficiently denitrify this compound. However, in contrast to B. cepacea, in liquid cultures this strain did not grow using 2,4-DNT as a sole carbon source and showed an incomplete DNT degradation with accumulation of toxic intermediate metabolites. In this work we now show that additional insertion of the recently described lower biodegradative pathway genes allowed an efficiently 2,4-DNT biodegradation without the accumulation of toxic intermediates. This new modified strain efficiently uses N from 2,4-DNT when the media was supplemented with a simple C source. Moreover, determination of the biodegradation products by HPLC indicated that the growth and the 2,4-DNT biodegradation rate were maximal when the media was supplemented with a complex C source, suggesting that this strain produces a 2,4-DNT cometabolic mineralization. In addition, in the absence of DNT the modified P.fluorescens strain, in contrast to B. cepacea, stably maintains the dnt inserted genes after many generations. These results open the possibility to develop an innocuous and phenotypically stable strain for biodegradative processes.