Biodegradation of nitroglycerin in porous media and potential for bioaugmentation with Arthrobacter sp. strain JBH1.

Nitroglycerin (NG) is a toxic explosive found as a contaminant of soil and groundwater. Several microbial strains are capable of partially reducing the NG molecule to dinitro or mononitroesters. Recently, a strain capable of growing on NG as the sole source of carbon and nitrogen (Arthrobacter sp. strain JBH1) was isolated from contaminated soil. Despite the widespread presence of microbial strains capable of transforming NG in contaminated soils and sediments, the extent of NG biodegradation at contaminated sites is still unknown. In this study column experiments were conducted to investigate the extent of microbial degradation of NG in saturated porous media, specifically after bioaugmentation with JBH1. Initial experiments using sterile, low sorptivity sand, showed mineralization of NG after bioaugmentation with JBH1 in the absence of sources of carbon and nitrogen other than NG. Results could be modeled using a first order degradation rate of 0.14d(-1). Further experiments conducted using contaminated soil with high organic carbon content (highly sorptive) resulted in column effluents that did not contain NG although high dinitroester concentrations were observed. Bioaugmentation with JBH1 in sediments containing strains capable of partial transformation of NG resulted in complete mineralization of NG and faster degradation rates.