Atrazine-degrading Strain Research Articles

Inoculation of an atrazine-degrading strain, Chelatobacter heintzii Cit1, in four different soils: effects of different inoculum densities

The possibility to improve atrazine degradation in soils by bioaugmentation was studied. The atrazine-mineralizing strain, Chelatobacter heintzii Cit1, was inoculated in four sterile and four non-sterile soils, at varying inoculum densities. Two soils, which had shown enhanced atrazine mineralization, were used to determine which inoculum density was capable of restoring their original mineralizing capacity after sterilization. The two other soils, with intermediate and low capacity to mineralize atrazine, were used in order to demonstrate that atrazine mineralization in such soils could be improved by inoculation. Mineralization kinetics were fitted using the Gompertz model. In the case of soils adapted to atrazine mineralization, inoculation of C. heintzii did not accelerate the rate of atrazine mineralization, which was essentially performed by the indigenous microflora. However, with soils that did not mineralize atrazine, the introduction of 10 4 cfu g −1 resulted in a 3-fold increase of atrazine mineralization capacity.

Plasmid localisation of atrazine-degrading genes in newly described Chelatobacter and Arthrobacter strains

Abstract In a previous study, we isolated a collection of atrazine-degrading bacteria from various soils. The aim of this study was to localise the atrazine-degrading genes in these 25 atrazine-degrading strains. In the case of the Gram-negative strains of Chelatobacter heintzii, six to seven plasmids were observed. The atzABC and trzD genes were located on two or three plasmids with variable molecular masses. For the Gram-positive strains of Arthrobacter crystallopoietes, the atzBC genes were located on a single plasmid of 117 kb. The organisation of atrazine-degrading genes seems to be highly variable between the strains studied. We have shown by a specific PCR the occurrence of IS1071-like sequences in all strains carrying atzBC genes, while these sequences seem to be absent in strains carrying only the atzA gene. Thus, we show a strong correlation between the presence of these insertion sequences and the presence of some genes involved in atrazine degradation.

Plasmid localisation of atrazine-degrading genes in newly described Chelatobacter and Arthrobacter strains

In a previous study, we isolated a collection of atrazine-degrading bacteria from various soils. The aim of this study was to localise the atrazine-degrading genes in these 25 atrazine-degrading strains. In the case of the Gram-negative strains of Chelatobacter heintzii, six to seven plasmids were observed. The atzABC and trzD genes were located on two or three plasmids with variable molecular masses. For the Gram-positive strains of Arthrobacter crystallopoietes, the atzBC genes were located on a single plasmid of 117 kb. The organisation of atrazine-degrading genes seems to be highly variable between the strains studied. We have shown by a specific PCR the occurrence of IS 1071-like sequences in all strains carrying atzBC genes, while these sequences seem to be absent in strains carrying only the atzA gene. Thus, we show a strong correlation between the presence of these insertion sequences and the presence of some genes involved in atrazine degradation.