Journal of Biotechnology & Biomaterials
Open Access

Abstract

The present work is a comparative study aimed to isolate, identify and acclimatize Atrazine-resistant soil bacteria from different contaminated soils in order to be used for bioremediation of polluted environments. Bacteria were isolated from three corn and cucumber-cultivated Egyptian and Saudi soils where Atrazine was applied at 3 elevated doses, half the recommended dose (1/2 RD), recommended dose (RD) and double the recommended dose (2X RD). Physical, chemical, mechanical and biological properties of soils were characterized. Indigenous as well as exogenous bacteria (PF, PS and PQ) were subjected to a preliminary screening toxicity test at Atrazine RD followed by enrichment culturing at 2X RD of the herbicide. Toxicity screening resulted in 23-soil isolate best grown in the presence of at the Atrazine. Sequences of the tested isolates were affiliated according to their 16S rDNA to members of 5 genera namely Enterobacter (E. cloacae),Bacillus(B. cereus and B. anthracis),Pseudomonas(P. aeruginosa, P. balearica, P. indicaand P. otitidis),Ochrobactrum(O. intermedium) and Providencia(P. vermicola) with similarities ranged between 91 and 99%. Resistant bacteria were individually enriched in 2X RD Atrazine amended-liquid cultures for 10 daysto select the most promising acclimatized bacteria for biodegradation of Atrazine from the contaminated soils. Results revealed quantitative and qualitative variations in soil bacterial populations based on the natural characteristics of the soil and Atrazine concentration. Seven bacterial species belong to 4 genera ( Enterobacter, Pseudomonas, Bacillus and Providencia ) were found superior in their resistance to Atrazine where they exhibited remarkable stimulation (S: 70.7-88.7%) in their growth. Therefore, they considered acclimatized, highly Atrazine-resistant and can efficiently be used for the degradation of Atrazine-contaminated soil and/or wastewater. Screening different proposed bioremediation technologies proved that bioaugmentation coupled with biostimulation is the most promising remediation technique since it is powerful, economical and environmentally friendly bioremediation technique for decontamination of Atrazine-contaminated soils.

Biography

N Zabermawi is an Assistant Professor of Applied Microbiology. She is currently working as Lecturer, Department of Life Sciences, Faculty of Science, King Abdul Aziz University, Jeddah, Kingdom of Saudi Arabia. She completed her Master degree in Microbiology 2006 in King Abdul Aziz University, Saudi Arabia, Jeddah and her PhD in Applied Microbiology 2013 from the same University as well. Her research interests include first study and monitoring of environmental pollutants either organic (pesticides; crude oil etc.) or inorganic (e.g. heavy metal etc.) in aquatic environments and contaminated soils.