Microbial Degradation of 2,4,6-Trinitrotoluene (TNT) and Bioremediation of Contaminated Areas with TNT

Abstract

2,4,6-trinitrotoluene (TNT) is a widely used explosive chemical. TNT was used as the main explosive in both two World wars due to characteristics such as safe manufacture and storage of TNT, its low melting point and its chemical and thermal stability. The manufacturing, use and disposal of TNT for military activities have caused contamination of both soil and groundwater. Although TNT is widely used as an explosive material, there are toxic effects of TNT on many organisms including humans and because of the symmetrical arrangement of the nitro groups in the structure of TNT, it can be stay in nature without degradation for a long time. Remediation of soil and groundwater contamination caused by TNT with biological approaches is very important in terms of human health and ecosystems. The availability of biological treatment of a toxic compound depends on the possibility of biodegradation of the compound. Though TNT is persistent in nature for a long time, it is sensitive to microbial attacks. A variety of aerobic and anaerobic bacteria and fungi can degrade TNT and TNT’s transformation metabolites with nitroreductase enzymes which they synthesize. For the remediation of contaminated areas with TNT, various biological-based technologies employing microorganisms that are capable of degrading TNT have been developed. In this study, by examining relevant literature, microbial degradation mechanisms of TNT and microorganism species that have TNT degradation capacity have been designated. Furthermore, bioremediation methods used for the treatment of contaminated sites with TNT were investigated, studies on the implementation of the methods and advantages and disadvantages of these methods in practice were compiled from literature sources. 

Keywords

• Nitroaromatic compounds
• 2 4 6-trinitrotoluene
• microbial degradation
• bioremediation

2,4,6-Trinitrotoluen (TNT)’in Mikrobiyal Degradasyonu ve TNT ile Kirlenmiş Bölgelerin Biyoremediasyonu

Öz

2,4,6-trinitrotoluen (TNT) yaygın olarak kullanılan patlayıcı bir kimyasaldır. TNT güvenli üretimi ve depolanması, düşük erime noktası, kimyasal ve termal kararlılığı gibi özelliklerinden dolayı her iki dünya savaşında ana patlayıcı madde olarak kullanılmıştır. TNT’nin askeri faaliyetler için imalatı, kullanımı ve imha edilmesi hem toprak hem de yeraltı sularının kirlenmesine neden olmaktadır. TNT’nin yaygın olarak patlayıcı madde olarak kullanılmasına karşın insan dahil birçok organizma üzerinde toksik etkileri vardır ve TNT yapısında bulunan nitro gruplarının simetrik düzeninden dolayı doğada uzun süre bozunmadan kalabilmektedir. TNT’nin hem yer altı sularında hem de toprakta neden olduğu kirliliğin biyolojik yöntemlerle remediasyonu insan sağlığı ve ekosistem açısından oldukça önemlidir. Bir toksik bileşiğin biyolojik olarak muamele edilebilirliği bu bileşiğin biyodegradasyonunun mümkün olmasına bağlıdır. TNT doğada uzun süre bozunmadan kalabilmesine karşın mikrobiyal ataklar karşısında hassastır. Çeşitli aerobik ve anaerobik bakteriler ve mantarlar sentezledikleri nitroredüktaz enzimleri ile TNT ve TNT’nin transformasyon metabolitlerini parçalayabilmektedir. TNT ile kirlenmiş bölgelerin ıslahı için, TNT’yi parçalayabilme yeteneğine sahip mikroorganizmaların kullanıldığı çeşitli biyolojik temelli teknolojiler geliştirilmiştir. Bu çalışmada konuyla ilgili literatür incelenerek TNT’nin mikrobiyal degradasyon mekanizmaları ve TNT degradasyon kapasitesine sahip mikroorganizma türleri belirlenmiştir. Ayrıca, TNT ile kirlenmiş bölgelerin ıslahında kullanılan biyoremediasyon yöntemleri araştırılmış, yöntemlerin uygulanmasına ait çalışmalar ve yöntemlerin uygulamadaki avantaj ve dezavantajları literatür kaynaklarından derlenmiştir. 

Anahtar Kelimeler

• Nitroaromatik bileşikler
• mikrobiyal degradasyon
• biyoremediasyon
• 2 4 6-trinitrotoluen

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