Biodegradation of hexahydro-1,3,5-trinitro-1,3,5-triazine by novel fungi isolated from unexploded ordnance contaminated marine sediment

Abstract

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 14 CO 2 . Subsequently we selected Acremonium to determine biotransformation pathway(s) of RDX in more details. When RDX (100 lM) was incubated with resting cells of Acremonium we detected methylenedinitramine (MEDINA), N 2 O 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 N 2 O 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.

Biodegradation of RDX and MNX with Rhodococcus sp. Strain DN22: New Insights into the Degradation Pathway

“…Aliquots from the liquid culture media described above were centrifuged at 16 000g for 4 min using an Eppendorf Centrifuge 5415 D (Eppendorf AG, Hamburg) and the supernatant was used for chemical analysis. We determined RDX, MNX, and HCHO by HPLC (22) and NO 2 -, NO 3 -, and HCOOH by ion chromatography (23). Nitrous oxide was analyzed by GC/ECD (22).…”

Aerobic biotransformation of 2,4-dinitroanisole in soil and soil Bacillus sp.

“…Mass range was scanned from 40 to 1000 Da. We determined HCHO by HPLC (Bhatt et al 2006) and NO 2 -and NO 3 -by ion chromatography (Balakrishnan et al 2004). Measurement of methanol was made on an Agilent 6890 gas chromatograph equipped with a flame ionization detector (FID).…”

Pollutants Biodegradation by Fungi

“…Using sediment from a coastal UXO field, Oahu Island, Hawaii, four novel aerobic RDXdegrading fungi HAW-OCF1, HAW-OCF2, HAW-OCF3 and HAW-OCF5 were isolated and tentatively identified as members of Rhodotorula, Bullera, Acremonium and Penicillium, respectively. The four isolates mineralized 15-34% of RDX (94) [294]. Royal Demolition Explosive (RDX) (94) was also degraded by white-rot fungi, showing that the removal efficiency in wastewater could reach 87% under optimum conditions [295,296].…”