Etude de la biodégradation de l’ortho-nitrophénol et du para-nitrophénol par le microbiote des eaux usées et mise en évidence des bactéries dominantes impliquées dans ce processus

Abstract

Biodegradation of ortho-Nitrophenol (ONP) and para-Nitrophenol (PNP) by wastewater’s microflora is studied. Isolation and identification of microorganisms implicated is also carried out. The cultures are performed using a minimum medium, where Nitrophenol is the sole source of carbon, energy and nitrogen at 500 mg/L. The kinetic of biodegradation is followed for more than 30 days of incubation. The obtained results show that more than 90% of initial concentration of PNP is decomposed at the end of 30 days of incubation and 77% of ONP in the same time of incubation. HPLC and GC-MS analysis permit to identify products and pathway's biodegradation of the two isomers. The isolation of microorganisms degrading PNP gave four bacterial colonies of different macroscopic aspects. However, three types of these bacterial are pigmented. Sequence analysis of 16S ribosomal RNA indicated that the ONP and the PNP degrading isolates were closely related to members of the species: Pseudomonas aeruginosa and Bacillus cereus.