Biotransformation of 2,4-dinitrotoluene by obligate marine Shewanella marisflavi EP1 under anaerobic conditions

• Reduction of 2,4-DNT by S. marisflavi EP1 was a process of microbial respiration.
• 200 μM 2,4-DNT was completely reduced by growing cells in 24 h.
• 2,4-DNT was reduced in a wide range of NaCl concentration (2–8%).
• Flavins enhanced the reduction of 2,4-DNT by EP1.
• Effective transformation occurred at a low temperature of 4 °C.

Anaerobic transformation of 2,4-DNT by obligate marine Shewanella marisflavi EP1 was investigated. The cell growth of EP1 was proportional to the total amount of 2,4-DNT reduced. The eventual transformation product was 2,4-diaminotoluene, via 2-amino-4-nitrotoluene and 4-amino-2-nitrotoluene as intermediates. The presence of Cu2+, dicumarol, metyrapone and flavins intensively influenced the reduction activity of 2,4-DNT, suggesting that dehydrogenease, menaquinone, cytochromes and flavins are essentially involved in electron transport process for 2,4-DNT reduction. These results indicate that biotransformation of 2,4-DNT by EP1 is a form of microbial anaerobic respiration. Furthermore, EP1 was capable of transforming 2,4-DNT at relatively alkaline range of pH (7–9), and at a wide range of temperature (4–40 °C) and salinity (2–8% NaCl concentration). Our findings not only deepen our understanding of the environmental fate of 2,4-DNT, but also provide an extension to the application of shewanellae in the site bioremediation and/or wastewater treatment.