Microbial degradation of polycyclic aromatic hydrocarbons and polycyclic aromatic nitrogen heterocyclics

Abstract

Fermentor studies were conducted to examine the microbial degradation of polycyclic aromatic hydrocarbons (PAHs; naphthalene, phenanthrene, anthracene) and a polycyclic aromatic nitrogen heterocyclic (quinoline) using a mixed bacterial culture capable of utilizing these compounds as the sole carbon and energy source for growth. Half-lives for the three PAHs in the cyclone fermentor system ranged from 1 day for naphthalene to 4 days for anthracene. Several major metabolites during the biodegradation of PAHs were also identified. These included 2-hydroxybenzoic acid and 1-naphthalenol (for naphthalene); 1-phenanthrenol and 1-hydroxy-2-naphthalenecarboxylic acid (for phenanthrene); and 3-hydroxy-2-naphthalenecarboxylic acid (for anthracene). Thus our bacterial culture biodegraded the three PAHs by initial hydroxylation of the molecule followed by the eventual cleavage of the ring to yield the ortho-or meta-cleavage intermediates, which would be further metabolized via conventional metabolic pathways. However, biodegradation of the nitrogen-containing polycyclic aromatic hydrocarbon compound quinoline by our culture resulted in the accumulation of 4-5 metabolites, one of which has been identified as 2-quinolinol. Work is in progress to identify the other metabolites from quinoline degradation. 0 1992 John Wiley & Sons.

Microbial transformation of metolachlor

“…The stable mixed bacterial culture had previously been shown to rapidly degrade low and medium molecular weight polynuclear aromatic hydrocarbons (PAHs) and polynuclear aromatic nitrogen heterocyclic (Liu et at., 1992). The experiments were conducted using mineral salt medium in glass-Teflon cyclone fermentors with the technical grade metolachlor at a final concentration of 10 mg/L (Liu et al, 1992). At various times, aliquots were withdrawn from the fermentors for the analysis of metolachlor and its metabolites.…”

Assays for the tertiary biological treatment of wastewater using autotrophic biomass

“…Another important aspect of autotrophic activated sludge is its use in the biodegradability study. To date, studies have been carried out using conventional activated sludge (Liu, 1993;Liu et al, 1992), but the biodegradability of autotrophic activated sludge has not yet been tested.…”

Environmental Fate And Effect Of Contaminants In Produced Water

“…These compounds are toxic, but not mutagenic/carcinogenic (3). Microbial degradation of these low molecular weight PAHs produces, as shortlived intermediates, a variety of phenols, quinones, dihydrodiols, alcohols, and acids (11).…”