title: Biodegradation of hexahydro-1,3,5-trinitro-1,3,5-triazine by novel fungi isolated from unexploded ordnance contaminated marine sediment.
abstract: Undersea deposition of unexploded ordnance (UXO) constitutes a potential source of contamination of marine environments by hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX). Using sediment from a coastal UXO field, Oahu Island, Hawaii, we isolated four novel aerobic RDX-degrading fungi HAW-OCF1, HAW-OCF2, HAW-OCF3 and HAW-OCF5, tentatively identified as members of Rhodotorula, Bullera, Acremonium and Penicillium, respectively. The four isolates mineralized 15-34% of RDX in 58 days as determined by liberated 14CO2. Subsequently we selected Acremonium to determine biotransformation pathway(s) of RDX in more details. When RDX (100 microM) was incubated with resting cells of Acremonium we detected methylenedinitramine (MEDINA), N2O and HCHO. Also we detected hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX) together with trace amounts of hexahydro-1,3-dinitroso-5-nitro-1,3,5-triazine (DNX) and hexahydro-1,3,5-trinitroso-1,3,5-triazine (TNX). Under the same conditions MNX produced N2O and HCHO together with trace amounts of DNX and TNX, but we were unable to detect MEDINA. TNX did not degrade with Acremonium. These experimental findings suggested that RDX degraded via at least two major initial routes; one route involved direct ring cleavage to MEDINA and another involved reduction to MNX prior to ring cleavage. Nitrite was only detected in trace amounts suggesting that degradation via initial denitration did take place but not significantly. Aerobic incubation of Acremonium in sediment contaminated with RDX led to enhanced removal of the nitramine.
authors.affiliation: Biotechnology Research Institute, National Research Council of Canada, Montreal, QC, Canada H4P 2R2.
authors.forename: Manish
authors.initials: M
authors.lastname: Bhatt
authors.forename: Jian-Shen
authors.initials: JS
authors.lastname: Zhao
authors.forename: Annamaria
authors.initials: A
authors.lastname: Halasz
authors.forename: Jalal
authors.initials: J
authors.lastname: Hawari
mesh_terms: D001673:Biodegradation, Environmental; D019015:Geologic Sediments / Q000382:microbiology*; D003904:Mitosporic Fungi / Q000145:classification / Q000302:isolation & purification / Q000378:metabolism*; D010802:Phylogeny; D012378:Rodenticides / Q000378:metabolism*; D014227:Triazines / Q000378:metabolism*
chemical_list: D012378:Rodenticides; D014227:Triazines; C009160:cyclonite