Etude de la tolérance au cuivre chez des isolats rhizosphériques de Pseudomonas fluorescents

Abstract

Pesticides are used in the fight against pests. Copper is the main active chemical component of pesticides and its daily use can promote the emergence of resistance in the microbial population, which results in several mechanisms. This work aims to isolate and characterize morphological and biochemical bacteria from the rhizosphere of a grass plant (rat barley, Hordeum murinum) in the region of Oued El Kheir and Sidi Lakhdar. Forty bacteria were isolated, of which 29 Pseudomonas-like species were subjected to a copper resistance test, These bacteria were tested at different doses (0.50, 1.2, 2.5, 3, 3.5, 4, 4.5 and 5 mM) of copper sulphates (CuSO4, 5H2O), showing resistance to copper especially for isolates K and 14. The determination of the minimum inhibitory concentration (MIC) of copper sulphate with respect to the best performing isolates indicates that the two fluorescent Pseudomonas bacteria (k and 14) are inhibited by the concentration of 1.6 mM. Evidence of the effect of copper sulphate on the growth of the two species of fluorescent Pseudomonas isolated in the two different medium (King B and BN) shows that copper has a cross-hair retarder effect, The identification by the API 20 NE biochemical galleries shows that the two isolates are close to Pseudomonas fluorescens.