Influence of pH on 2,4,6-trinitrotoluene degradation by Yarrowia lipolytica

Abstract

The microbial reduction of the aromatic ring of 2,4,6-trinitrotoluene (TNT) can lead to its complete destruction. The acid-tolerant yeast Yarrowia lipolytica AN-L15 transformed TNT through hydride ion-mediated reduction of the aromatic ring (as the main pathway), resulting in the accumulation of nitrite and nitrate ions, as well as through nitro group reduction (as minor pathway), resulting in hydroxylamino- and aminoaromatics. TNT transformation depended on the yeasts' ability to acidify the culture medium through the production of organic acids. Aeration and a low medium buffer capacity favored yeast growth and resulted in rapid acidification of the medium, which influenced the rate and extent of TNT transformation. This is the first time that nitrate has been detected as a major product of microbial TNT degradation, and this work demonstrates the importance of pH on TNT biotransformation. The ability of Y. lipolytica AN-L15 to reduce the TNT aromatic ring to form TNT-hydride complexes, followed by their denitration, makes this strain a potential candidate for bioremediation of sites contaminated with explosives.

Effect of the Organic Loading Rate Increase and the Presence of Zeolite on Microbial Community Composition and Process Stability During Anaerobic Digestion of Chicken Wastes

“…TS were measured by oven drying at 105°C for 16 h, and VS were subsequently analyzed by combusting the dry matter at 550°C for 3 h. Acid capacity of the effluents was determined using a T90 Mettler-Toledo titrator (Switzerland) according to the study by Ziganshin et al [65]. In addition, VFA concentrations were analyzed with a Dionex ion chromatograph equipped with an IonPac AS11 column [61,63]. Total ammonia nitrogen was analyzed in the liquid phase of reactors' effluents as the sum of NH 4 + -N and NH 3 -N by distillation and absorption in H 3 BO 3 followed by titration with H 2 SO 4 .…”

Aerobic degradation of 2,4-dinitrotoluene by individual bacterial strains and defined mixed population in submerged cultures

“…A second, related objective of this study was to examine how 2,4-DNT removal rates are influenced by environmental factors, such as pH, concentration of pollutants and the presence of other nitrotoluenes, which are by-products of toluene nitration [13]. These factors are known to affect 2,4-DNT bioavailability [14,15] and biodegradation [16,17]. Separation of microbiological and environmental factors is often a difficult task because the developing mixed cultures represent dynamic, complex and poorly defined microbial consortia.…”

Impact of TNT explosive and its degradation products on the environment

“…Sanacija zemljišta, površinskih voda i podzemnih voda zagađenih T T-om i sličnim jedinjenjima može se postići korišćenjem fizičkih, hemijskih i bioloških metoda. ako toksičan, T T ima veoma nisku pokretljivost u tlu [22]. Zbog toga se ovaj opasan otpad tretira isparavanjem do suvog jer toksične komponente nisu isparljive , nakon čega sledi spaljivanje [2].…”

“…Transformacija nitroaromatičnih jedinjenja generalno se javlja preko aerobnih bakterija koje imaju tendenciju da transformišu T T molekul tako što redukuju jednu ili dve nitro grupe u hidroksilamino ili amino grupe i proizvode različite izomere amino-nitroaromatičnih jedinjenja, koji se obično akumuliraju u određenom medijumu bez dalje degradacije. Na primer, uobičajeni posmatrani proizvodi redukcije TNT-a uključuju 2-amino-4,6dinitrotoluen (2-ADNT), 4-amino-2,6-dinitrotoluen (4-ADNT), 2,4-diamino-6-nitrotoluen (2,4-DANT) , 2,6-diamino-4-nitrotoluena (2,6-DANT) [2, 4,16,19,22,23]. Štetnost je dokazana testom akutne toksičnosti na glisti koji je izvršen koristeći šumsko zemljište kontaminirano TNT-om.…”