Optimized atrazine biodegradation in Egyptian soils via native bacterial isolates and molecular insights using different statistical methods

Forty four bacterial candidates isolated from Egyptian atrazine polluted soil sites, were examined to select atrazine bio-degraders. Among them thirty four were proved their ability to use it as nitrogen source. Strains HA19 and A7 gave the highest efficient rate to biodegrade atrazine with efficiency of 81% and 81.3%. They were identified and belonging taxonomically to Klebsiella sp. and Ochrobactrum sp. according to sequencing of 16S rRNA and phylogenetic analysis. Both of them confirmed their possession of atrazine degrading genes like atzA, atzC and atzD while atzB was appeared as faint band with strain A7 only. HPLC analysis indicated that the two strains degraded atrazine via the pathway of producing deethylatrazine as an important intermediate. Thus interesting data revealed the possibility of acquisition of these strains for two couples of atrazine degrading mechanisms located on chromosomal and plasmid sites. Applying the advanced statistical method of response surface methodology (RSM) based on central composite design (CCD) model has contributed to increase the biodegradation process with both strains by a rate of (94.2%) and (96.7%) on respectively. For our knowledge this article is one of condensed work and applicable way that will introduce bio safety solution for bioremediating atrazine and reducing its toxicity in agricultural polluted fields, as there is little reports from Egypt published before concerning atrazine bioremediation.