Denitration of glycerol trinitrate by resting cells and cell extracts of Bacillus thuringiensis/cereus and Enterobacter agglomerans

Abstract

A number of microorganisms were selected from soil and sediment samples which were known to have been previously exposed to nitrate ester contaminants. The two most effective bacteria for transforming glycerol trinitrate (GTN) were identified as Bacillus thuringiensis/cereus and Enterobacter agglomerans. For both isolates, denitration activities were expressed constitutively and GTN was not required for induction. Dialysis of cell extracts from both isolates did not affect denitration, which indicates that dissociable and depletable cofactors are not required for denitration. With thin-layer chromatography and high-performance liquid chromatography, the denitration pathway for both isolates was shown to be a sequential denitration of GTN to glycerol dinitrate isomers, glycerol mononitrate isomers, and ultimately to glycerol. GTN was observed to be completely converted to glycerol during a long-term incubation of cell extracts.

Aerobic Biodegradation of Nitroglycerin in a Sequencing Batch Reactor

“…The removal of nitrite after generation was probably the result of autotrophic NO 2 Ϫ -N oxidation. A mechanism involving hydrolytic cleavage of nitrate esters followed by reduction of nitrate to nitrite has been proposed before (Meng et al, 1995). The data in this study do not corroborate such a two-step enzymatic process for GTN degradation but suggest the direct denitration of GTN with the release of nitrite.…”

“…Because GDN denitration was the rate-limiting step in GTN conversion to glycerol, it was not possible to compare relative rates of GTN and GMN denitration. Some authors working with whole cells or isolated enzymes inferred that GDN denitration was nonconcomitant with GTN denitration (Meng et al, 1995, andWhite et al, 1996), whereas concomitant denitration of GTN and GDN was observed with isolated reductases (Blehert et al, 1997) and aerobic enrichment cultures (Accashian et al, 1998). In the current work, all nitrate esters were denitrated simultaneously and concomitantly because GDN removal occurred while GTN was still present and GMN isomers were never detected (Figure 4).…”

“…Biotransformation of GTN was reported as taking place stepwise via the dinitrate and mononitrate isomers, with each successive step proceeding at lower rates (Accashian et al, 1998;Blehert et al, 1997;Christodoulatos et al, 1997;Meng et al, 1995;and Wendt et al, 1978). The accumulation and subsequent removal of GDNs occurred in the absence of detectable GMNs, indicating that GMN denitration was faster than GDN denitration (Figure 4).…”

“…In the current work, all nitrate esters were denitrated simultaneously and concomitantly because GDN removal occurred while GTN was still present and GMN isomers were never detected (Figure 4). Most researchers working with pure cultures have observed incomplete GTN denitration (Blehert et al, 1997;Meng et al, 1995;Snape et al, 1997;and White et al, 1996), resulting in the accumulation of GMNs. In this study, GMNs did not accumulate, and GTN denitration was complete.…”

Biodegradation of glyceryl trinitrate by Penicillium corylophilum Dierckx

“…However, the degradation was not complete, as GDN and GMN were still present in the spent medium (19). Recently, Meng et al (10) reported that GTN can be completely denitrated during a long-term incubation with cell extracts of either Bacillus thuringiensis plus Bacillus cereus or Enterobacter agglomerans. Although the method of Meng et al appears to effectively degrade GTN, it must be pointed out that B. cereus and E. agglomerans are mammalian pathogens whereas B. thuringiensis is an insect pathogen (6,12,16).…”