Characterization of microbial community structure after application of different bioremediation approaches in TNT contaminated soil

Abstract

Contamination of the environment with explosive residues presents a serious problem at sites across the world. Trinitrotoluene (TNT) is one of the most commonly used explosive for military and industrial applications. In this study, bioaugmentation, biostimulation and phytoremediation were used as bioremediation strategies. Effect of the higher plants (rye Secale cereale and blue fenugreek Trigonella caerulea), amendments and specific bacteria consortium was studied in soil spiked with 118mg TNT/kg. Diversity of microorganisms and fate of TNT were evaluated after application of different bioremediation approaches. Results of Biolog Ecoplates data analysis showed that intensity of substrate assimilation by soil microbial community was altered by application of the consortium. The impact of vegetation on the microbial community metabolic profiles was also demonstrated. Shannon diversity index values obtained after 48 hours Biolog EcoPlates incubation, was the highest in the samples with rye and fenugreek cultivation. In unplanted soil samples, the Shannon diversity index rose when consortium of bacteria, nitroaromatic compounds and amendments were added. Inoculation of soil samples with mixture of bacterial isolates had effect on microbial community composition revealed by 16S rDNA-DGGE analysis. However, no clear effect of the vegetation on the microbial community structure was found according to DGGE results. The most pronounced effect of bioaugmentation and biostimulation for TNT degradation was shown in the variants with rye cultivation. At the same time, the use of qPCR method allowed to detect the most profound effect of biostimulation and bioaugmentation on soil microbiological parameters in case of blue fenugreek application.