Alternative plant protection using an indigenous bacterium (Stutzerimonas nitrititolerans) isolated from agricultural soil of potato fields in Western Algeria to biodegrade common pesticides

Nowadays, it is highly important to find ways to degrade pesticides residues from the environment. We studied degradation of carbamate, copper sulphate - Cymoxanil and Cycloxydim by using an indeginous bacterium Stutzerimonas nitrititolerans. This bacteria uses pesticides as source of carbon and solubilize them by their enzymatic machinery. Experiments were conducted using mineral salt medium (MSM) on agar supplemented with two different pesticides as sole carbon and energy source: carbamate and acetamiprid. These organic pesticides contain carbon (example of carbamate: NH2COOH). Growth of the bacteria could suggest that it has utilized the pesticide as its sole energy source, indicating its ability to degrade the pesticide. The effects of different factors on pesticides degradation were investigated such us pesticide tolerance. The bacteria were tested for the ability to tolerate high concentrations of pesticides to optimize the degradation conditions. The treatments consisted of carbon-free mineral salts medium (MSM) supplemented with pesticides that are usually used during cultivation of potato such as acetamiprid, carbamate, copper sulphate - Cymoxanil and Cycloxydim at increasing concentrations (70, 100, 200 and 500mgl-1). Bacterial growth was monitored by daily measurement of the optical density at 600 nm on UV-1600 Spectrophotometer. Only one strain (Labeled PF2 of Stutzerimonas nitrititolerans) showed potential to tolerate and mitigate the tested pesticides at high concentrations. Further, a phenotypic characterization was carried, and 16S rRNA gene sequencing analysis performed to identify the PF2 strain. Pesticides did not show any significant inhibitory effect on the isolate PF2. Comparison of sequences with GenBank database gave similarity with Stutzerimonas nitrititolerans with 99.74% of homology. A phylogenetic tree of Stutzerimonas nitrititolerans was constructed to show relationship to closely related bacteria. The potential and efficiency of the strain PF2 using pesticides can be considered as a qualitative leap in the field of pesticide bioremediation in agricultural soils.