Open AccessEngineering Pseudomonas fluorescens for Biodegradation of 2,4-Dinitrotoluene
Author(s) -
Mariela Roxana Monti,
Andrea M. Smania,
Georgina Fabro,
María Elena Alvarez,
Carlos E. Argaraña
Publication year - 2005
Publication title -
applied and environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.552
H-Index - 324
eISSN - 1070-6291
pISSN - 0099-2240
DOI - 10.1128/aem.71.12.8864-8872.2005
Subject(s) - pseudomonas fluorescens , burkholderia , strain (injury) , microbiology and biotechnology , plasmid , pseudomonas , biology , biodegradation , arabidopsis thaliana , nicotiana tabacum , bacteria , gene , biochemistry , mutant , genetics , ecology , anatomy
Using the genes encoding the 2,4-dinitrotoluene degradation pathway enzymes, the nonpathogenic psychrotolerant rhizobacteriumPseudomonas fluorescens ATCC 17400 was genetically modified for degradation of this priority pollutant. First, a recombinant strain designated MP was constructed by conjugative transfer fromBurkholderia sp. strain DNT of the pJS1 megaplasmid, which contains thednt genes for 2,4-dinitrotoluene degradation. This strain was able to grow on 2,4-dinitrotoluene as the sole source of carbon, nitrogen, and energy at levels equivalent to those ofBurkholderia sp. strain DNT. Nevertheless, loss of the 2,4-dinitrotoluene degradative phenotype was observed for strains carrying pJS1. The introduction ofdnt genes into theP.fluorescens ATCC 17400 chromosome, using a suicide chromosomal integration Tn5 -based delivery plasmid system, generated a degrading strain that was stable for a long time, which was designated RE. This strain was able to use 2,4-dinitrotoluene as a sole nitrogen source and to completely degrade this compound as a cosubstrate. Furthermore,P. fluorescens RE, but notBurkholderia sp. strain DNT, was capable of degrading 2,4-dinitrotoluene at temperatures as low as 10°C. Finally, the presence ofP. fluorescens RE in soils containing levels of 2,4-dinitrotoluene lethal to plants significantly decreased the toxic effects of this nitro compound onArabidopsis thaliana growth. Using synthetic medium culture,P. fluorescens RE was found to be nontoxic forA.thaliana andNicotiana tabacum , whereas under these conditionsBurkholderia sp. strain DNT inhibitedA.thaliana seed germination and was lethal to plants. These features reinforce the advantageous environmental robustness ofP. fluorescens RE compared withBurkholderia sp. strain DNT.