Anaerobic Degradation of Phenolic Compounds

Abstract

Mononuclear aromatic compounds are degraded anaerobically through three main pathways, the benzoyl-CoA pathway, the resorcinol pathway, and the phloroglucinol pathway. Various modification reactions channel a broad variety of mononuclear aromatics including aromatic hydrocarbons into either one of these three pathways. Recently, a further pathway was discovered with hydroxyhydroquinone as central intermediate through which especially nitrate-reducing bacteria degrade phenolic compounds and some hydroxylated benzoates. Comparison of the various strategies taken for the degradation of aromatics in the absence of oxygen demonstrates that the biochemistry of breakdown of these compounds is determined largely by the overall reaction energetics and, more precisely, by the redox potentials of the electron acceptor systems used. Nitrate reducers differ in their strategies significantly from those used by sulfate-reducing or fermenting bacteria.

Allelopathic effects of submerged macrophytes on phytoplankton

“…Müller et al (2007) were the first to show that distinct bacterial groups isolated from the biofilm and the surrounding water column of the allelopathically active submerged macrophyte M. spicatum are able to degrade polyphenolic allelochemicals. This was surprising as polyphenols are known for their anti-bacterial properties (Walenciak et al, 2002), and polyphenol degrading bacteria were only known from anaerobic environments (Mahadevan and Muthukumar, 1980;Schink et al, 2000). Specialized bacteria in the vicinity of allelopathically active submerged macrophytes might be thus one reason for the rapid disappearance of allelochemicals from the water column.…”

Anaerobic Catabolism of Aromatic Compounds: a Genetic and Genomic View

“…The greatest energy conservation is reached when nitrate is the final electron acceptor, followed by ferric ion. The energy conservation when sulfate is the electron acceptor is much more limited (110,128,153,261,320,374). Fermentative bacteria can also use aromatic compounds, but usually, complete biodegradation becomes energetically feasible when accompanying methanogens or sulfate reducers use the metabolic end products, such as hydrogen, that are generated by the fermenters (106,107,168,288,289).…”

Initial steps in the fermentation of 3-hydroxybenzoate by Sporotomaculum hydroxybenzoicum

“…Monohydroxybenzoates (2-, 3-, and 4-hydroxybenzoate) are frequently occurring intermediates in the aerobic and anaerobic biodegradation of organic matter (Heider and Fuchs 1997;Schink et al 2000). Under anoxic conditions, 2-and 4-hydroxybenzoate are degraded by an activation step to the respective CoA-ester in a ligase reaction and by subsequent reductive dehydroxylation leading to benzoyl-CoA as a central intermediate, as studied mainly with nitrate-reducing and anoxygenic phototrophic bacteria (Heider and Fuchs 1997;Harwood et al 1999).…”