title: Improved RDX detoxification with starch addition using a novel nitrogen-fixing aerobic microbial consortium from soil contaminated with explosives.
abstract: In this work, we developed and characterized a novel nitrogen-fixing aerobic microbial consortium for the complete detoxification of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). Aerobic RDX biodegradation coupled with microbial growth and nitrogen fixation activity were effectively stimulated by the co-addition of starch and RDX under nitrogen limiting conditions. In the starch-stimulated nitrogen-fixing RDX degradative consortium, the RDX degradation activity was correlated with the xplA and nifH gene copy numbers, suggesting the involvement of nitrogen fixing populations in RDX biodegradation. Formate, nitrite, nitrate, and ammonia were detected as aerobic RDX degradation intermediates without the accumulation of any nitroso-derivatives or NDAB (4-nitro-2,4-diazabutanal), indicating nearly complete mineralization. Pyrosequencing targeting the bacterial 16S rRNA genes revealed that the Rhizobium, Rhizobacter and Terrimonas population increased as the RDX degradation activity increased, suggesting their involvement in the degradation process. These findings imply that the nitrogen-fixing aerobic RDX degrading consortium is a valuable microbial resource for improving the detoxification of RDX-contaminated soil or groundwater, especially when combined with rhizoremediation.
authors: School of Civil and Environmental Engineering, College of Engineering, Yonsei University, Seoul 120-749, Republic of Korea; Department of Agronomy, University of Agriculture, Faisalabad 38040, Pakistan.
authors: Muhammad Imran
authors: MI
authors: Khan
authors: School of Civil and Environmental Engineering, College of Engineering, Yonsei University, Seoul 120-749, Republic of Korea.
authors: Jihoon
authors: J
authors: Yang
authors: School of Civil and Environmental Engineering, College of Engineering, Yonsei University, Seoul 120-749, Republic of Korea.
authors: Byungun
authors: B
authors: Yoo
authors: School of Civil and Environmental Engineering, College of Engineering, Yonsei University, Seoul 120-749, Republic of Korea. Electronic address: parkj@yonsei.ac.kr.
authors: Joonhong
authors: J
authors: Park
mesh_terms: D000641:Ammonia / Q000378:metabolism; D001419:Bacteria / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D001673:Biodegradation, Environmental; D004269:DNA, Bacterial / Q000032:analysis; D053834:Explosive Agents / Q000378:metabolism*; D005561:Formates / Q000378:metabolism; D059013:Microbial Consortia / Q000502:physiology*; D008969:Molecular Sequence Data; D009566:Nitrates / Q000378:metabolism; D009573:Nitrites / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism; D009586:Nitrogen Fixation; D012336:RNA, Ribosomal, 16S / Q000032:analysis; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000378:metabolism*; D013213:Starch / Q000378:metabolism*; D014227:Triazines / Q000378:metabolism*
chemical_list: D004269:DNA, Bacterial; D053834:Explosive Agents; D005561:Formates; D009566:Nitrates; D009573:Nitrites; D012336:RNA, Ribosomal, 16S; D012989:Soil Pollutants; D014227:Triazines; C030544:formic acid; D000641:Ammonia; D013213:Starch; D009584:Nitrogen; C009160:cyclonite
keywords: Explosives; Microbial degradation; Nitrogen fixation; Pyrosequencing; Rhizobium; Rhizoremediation