Biotransformation of Trinitrotoluene (TNT) by Newly Isolated Slight Halophilic Bacteria

Abstract

Current study reports isolation of newly isolated slight halophilic bacteria which can utilize 2,4,6-trinitrotoluene (TNT) as a sole nitrogen source, leading to its detoxification. Among 100 halo(alkali)tolerant and halo(alkali)philic strains were isolated from TNT-contaminated soil, two slight halophilic alkalitolerant strains showed remarkable ability to quickly remove the different concentrations of TNT up to 200 mg/L during 24 h in aerobic condition. Phylogenetic analysis indicates that both strains belonged to the genus Pseudomonas which were able to grow aerobically in different concentrations of NaCl (up to 5 and 10%, respectively), temperature (25–40°C), and pH (7–9). Kinetic studies of TNT biotransformation process showed this growth-associated process followed the first-order expression with parameters of kd: 0.09–0.11 mg/(L h), Т1/2: 6–7 h, μ: 0.17–0.25 1/h leading to a removal of 90% of TNT (100 mg/L) during a 24 hour period. Finally, the growth rate of both strains evaluated on minimal and complex media, and growth parameters were optimized for maximum growth and most likely maximum biotransformation.