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Titolo:
Anaerobic oxidation of the aromatic plant hydrocarbon p-cymene by newly isolated denitrifying bacteria
Autore:
Harms, G; Rabus, R; Widdel, F;
Indirizzi:
Max Planck Inst Marine Mikrobiol, D-28359 Bremen, Germany Max Planck Inst Marine Mikrobiol Bremen Germany D-28359 Bremen, Germany
Titolo Testata:
ARCHIVES OF MICROBIOLOGY
fascicolo: 5, volume: 172, anno: 1999,
pagine: 303 - 312
SICI:
0302-8933(199911)172:5<303:AOOTAP>2.0.ZU;2-K
Fonte:
ISI
Lingua:
ENG
Soggetto:
SULFATE-REDUCING BACTERIUM; INITIAL REACTIONS; THAUERA-AROMATICA; CRUDE-OIL; TOLUENE METABOLISM; PSEUDOMONAS-PUTIDA; ENRICHMENT CULTURE; MOLECULAR-OXYGEN; PURE CULTURES; O-XYLENE;
Keywords:
anaerobic degradation; denitrifying bacteria; aromatic hydrocarbons; alkylbenzenes; p-cymene; alkylbenzoates; intermediates; 16S rRNA sequence analysis;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
46
Recensione:
Indirizzi per estratti:
Indirizzo: Widdel, F Max Planck Inst Marine Mikrobiol, Celsiusstr 1, D-28359 Bremen, Germany Max Planck Inst Marine Mikrobiol Celsiusstr 1 Bremen Germany D-28359
Citazione:
G. Harms et al., "Anaerobic oxidation of the aromatic plant hydrocarbon p-cymene by newly isolated denitrifying bacteria", ARCH MICROB, 172(5), 1999, pp. 303-312

Abstract

The capability of nitrate-reducing bacteria to degrade alkyltoluenes in the absence of molecular oxygen was investigated with the three isomers of xylene, ethyl toluene, and isopropyltoluene (cymene) in enrichment cultures inoculated with freshwater mud. Denitrifying enrichment cultures developed most readily (within 4 weeks) with p-cymene, a natural aromatic hydrocarbon occurring in plants, and with In-xylene (within 6 weeks). Enrichment of denitrifiers that utilized m-ethyltoluene and p-ethyltoluene was slow (within 8 and 12 weeks, respectively); no enrichment cultures were obtained with the other alkylbenzenes within 6 months. Anaerobic degradation of p-cymene, which has not been reported before, was studied in more detail. Two new types of denitrifying bacteria with oval cells, strains pCyN1 and pCyN2, were isolated; they grew on p-cymene (diluted in an inert carrier phase) and nitrate with doubling rimes of 12 and 16 h, respectively. Strain pCyN1, but notstrain pCyN2, also utilized p-ethyltoluene and toluene. Both strains grew with some alkenoic monoterpenes structurally related to p-cymene, e.g., alpha-terpinene. In addition, the isolates utilized p-isopropylbenzoate, and mono- and dicarboxylic aliphatic acids. Determination of the degradation balance of p-cymene and growth with acetate and nitrate indicated the capacityfor complete oxidation of organic substrates under anoxic conditions. Adaptation studies with cells of strain pCyN1 suggest the existence of at leasttwo enzyme systems for anaerobic alkylbenzene utilization, one metabolizing p-cymene and p-ethyltoluene, and the other metabolizing toluene. Excretion of p-isopropylbenzoate during growth on p-cymene indicated that the methyl group is the site of initial enzymatic attack. Although both strains werefacultatively aerobic, as revealed by growth on acetate under air, growth on p-cymene under oxic conditions was observed only with strain pCyN1. Strains pCyN1 and pCyN2 are closely related to members of the Azoarcus-Thauera cluster within the beta-subclass of the Proteobacteria, as revealed by 16S rRNA gene sequence analysis. This cluster encompasses several described denitrifiers that oxidize toluene and other alkylbenzenes.

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Documento generato il 28/09/20 alle ore 18:39:45