Structure—biodegradation correlation of polyphenols forThauera aromaticain anaerobic conditions

Abstract

The anaerobic degradation of phenolic compounds depends greatly on their molecular structure. We have undertaken a systematic study on several phenol derivatives which are commonly found in industrial waters with the aim of investigating the structure-biodegradation relationship for bacteria in anaerobic conditions. The Thauera aromatica strain was used; this bacterium is able to use phenol as a sole carbon source in liquid cultures in the absence of molecular oxygen. Nitrate is the electron sink with complete reduction to N 2 . A systematic study has demonstrated the ability of this bacterial strain to use 3,4-dihydroxybenzoic acid, 4-hydroxycinnamic acid (p-coumaric acid), 4-hydroxy-3-methoxycinnamic acid (ferulic acid), 3,4-dimethoxybenzoic acid (veratric acid), and 3,4,5-trihydroxybenzoic acid (gallic acid) as substrate. The matching of the depletion of the concentration of such compounds with the increment in bacterial growth in the cultures demonstrates that the substrates are used as the sole carbon source. Also, a correlation between the rate of growth of bacteria and nitrite concentration has been observed. The progressive reduction in nitrate into nitrite and N 2 is monitored through analyses. The protein pattern extracted from bacteria grown on methylated substrates is now being compared with that of bacteria grown on non-methylated polyphenols that are structurally analogous in order to identify specific enzymes for demethylation processes.

Isolation and characterization of polyphenols-degrading bacteria from olive-mill wastewaters polluted soil

“…The degradation of the phenolic compounds is strictly correlated to their chemical structure: the substrates characterized by the presence of more than two -OCH 3 groups in the molecular structure (3,4-dimethoxy benzoic acid, 3,4,5-trimethoxy benzoic acid and 3,5-dimethoxy-4-hydroxy benzoic acid) were not used as source of carbon by the bacteria. This finding is similar to what we have found with anaerobic bacteria (Dibenedetto et al 2006). With the exception of cathecol, the degradation of the considered phenols was strictly strain dependant.…”

“…synxantha, while it was recently shown the ability of P. oryzihabitans to degrade catechol (Jussila et al 2007). Using T. aromatica under anaerobic conditions, we have already demonstrated (Dibenedetto et al 2006) that polymethylated phenols of complex molecular structure are much less degraded with respect to simple phenols. In order to verify whether such correlation structure-degradation does hold also for aerobic bacteria, we have used several phenols among which veratric-, syringyc-, and 3,4,5-trimethylbenzoic acids as sole carbon source with bacteria isolated from soil.…”

“…In the course of our previous studies aimed at establishing a correlation between the molecular structure of polyphenols and their biodegradability, we have discovered that anaerobic bacteria (Thauera aromatica K172) can adapt to grow on several polyphenols and to use them as sole source of carbon, although growing the molecular complexity, the ability to adapt to the polyphenols decreases and polymethylated phenols are hardly degraded (Aresta et al 2001(Aresta et al , 2003Dibenedetto et al 2006).…”

Biological characteristics of a denitrifying phosphorus-accumulating bacterium

“…Thauera belongs to Rhodocyclaceae, b-Rhodocyclales. They are important microorganisms widely present in wastewater treatment apparatuses and the dominant microorganisms in various denitrification reactors, and they can degrade phenol, polyphenols, toluene, and quinoline (Dibenedetto et al, 2006). In this study, N11 was screened using conventional separation methods and was found to reduce NO 3 À -N to NO 2 À -N and then to N 2 .…”

Salicylic-Acid-Mediated Enhanced Biological Treatment of Wastewater

“…In our study, the clone library of the biomass before acclimatization demonstrated a very diverse population showing sequences homologous to Hyphomicrobium, a soil bacteria reported in methanol-degrading consortium [25], Desulfuromonas, a sulfate-reducing bacterium studied mainly for its dehalogenation of di-, tri-, and tetra-chloroethanes [26,27], and Collinsella, a bacterium reported in fecal samples. After acclimatization, besides the unidentified bacteria, certain clone sequences were identified as bacteria showing homology to genera like Rhodobacter [28,29], Sphingomonas [30][31][32], Thauera [33,34], etc., which are widely reported in the degradation of aromatics.…”