Biotransformation of p-toluic acid in anoxic estuarine sediments under a CO2 or N2/H2 atmosphere

• Published in: Chemosphere (Oxford) Vol. 45; no. 6-7; pp. 835 - 842
• Main Authors: KUO, C.-E, CHI, W.-C, LIU, S.-M
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier 01-11-2001
• Subjects: Applied sciences; Bacteria; Benzoates - metabolism; Biological and physicochemical properties of pollutants. Interaction in the soil; Biotransformation; Carbon Dioxide - chemistry; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Exact sciences and technology; Geologic Sediments; Hypoxia; Nitrogen - chemistry; Pollution; Pollution, environment geology; Population Dynamics; Soil and sediments pollution; Water Pollutants, Chemical - metabolism; Asia; Taiwan; Biodegradation; Microbial activity; Laboratory study; Sulfate-reducing bacteria; Pollutant behavior; Estuaries; Sediments; Controlled atmosphere; Microbial biomass; Pollution; Carboxylic acid; Medium effect; Methanogenic bacteria; Biotransformation; Headspace; Aromatic compound; Population dynamics; Acetic acid bacteria; Microbial community
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/S0045-6535(01)00098-4

The composition of the headspace gas affected the growth dynamics of microbial populations and the biotransformation pattern of p-toluic acid in anoxic estuarine sediments. Under CO2 atmosphere, p-toluic acid was transformed by the sediment microorganisms without a lag period, while under N2/H2 atmosphere, p-toluic acid was transformed after a lag period of 55 days. Under the N2/H2 atmosphere, the methanogen population, following a rapid increase of almost two orders of magnitude, remained at a high level until just before the onset of biotransformation. We hypothesize that during the lag period, the hydrogenotrophic methanogens were removing the H2, a step which is essential before the reaction can be exergonic. Acetogenic bacteria did not initiate decarboxylation as the first step of biotransformation under either atmosphere. Neither the methanogens nor the acetogenic bacteria appeared to be directly involved in the biotransformation of p-toluic acid under either atmosphere. Under the CO2 atmosphere, biotransformation of p-toluic acid involved sulfate-reducing bacteria, while under N2/H2, both sulfate-reducing bacteria and other eubacteria were involved.