Enrichment and properties of an anaerobic mixed culture that reductively deiodinates 5-amino-2,4,6-triiodoisophthalic acid, an X-ray contrast agent precursor

• Published in: Applied microbiology and biotechnology Vol. 62; no. 5-6; pp. 550 - 556
• Main Authors: LECOUTURIER, D, ROCHEX, A, LEBEAULT, J.-M
• Format: Journal Article
• Language: English
• Published: Berlin Springer 01.10.2003; Springer Nature B.V
• Subjects: 5-amino-2,4,6-triiodoisophthalic acid; Acetates - metabolism; Acids; Alcohol; Alcohol, Denatured; Amino acids; Anaerobiosis; Bacteria; Biodegradation, Environmental; Biological and medical sciences; Biology of microorganisms of confirmed or potential industrial interest; Biotechnology; Butyrates - metabolism; Chemical properties; Contrast Media - metabolism; Culture Media; Electrons; Ethanol; Ethanol - metabolism; Fundamental and applied biological sciences. Psychology; Iodides; Iodides - analysis; Lactic Acid - metabolism; Microbiology; Mission oriented research; Nitrates - metabolism; Observations; Phthalic Acids - analysis; Phthalic Acids - metabolism; Physiology and metabolism; Sewage - microbiology; Sludge; Sulfates; Sulfates - metabolism; Sulfites - metabolism; Thiosulfates - metabolism; Triiodobenzoic Acids - metabolism; Wastewater; Wastewater treatment plants; Water Pollution, Chemical; France; Biodegradation; Enrichment; Anaerobe; X ray radiography; Mixed microorganism culture; Iodine Organic compounds; Precursor; Contrast media; Deiodination
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/s00253-003-1296-5

5-Amino-2,4,6-triiodoisophthalic acid (ATIA), both a precursor and a degradative intermediate of triiodinated contrast media, was anaerobically converted by sludge from a wastewater treatment plant. ATIA conversion took place only when an electron donor such as ethanol was added. A stable mixed culture was established by transfer to a defined synthetic mineral medium with ATIA and ethanol. It could be maintained for 1 year when the sulfate concentration was kept below 30 microM. Transient appearance of 5-amino-2,4-diiodoisophthalic acid, iodide release (2.7 mol iodide/mol ATIA) and accumulation of 5-aminoisophthalic acid indicated that ATIA was reductively dehalogenated. The enriched mixed culture also dehalogenated ATIA derivatives but deiodination remained incomplete. ATIA was the sole terminal electron acceptor used by the mixed culture during deiodination. The ratio of electrons transferred to ATIA, 0.83, was consistent with a respiratory metabolism. Formate, acetate, lactate, butyrate and hydrogen were also used as electron donors. Deiodination was inhibited by a headspace of air or by addition of nitrate, sulfite or thiosulfate. The reaction was 2.6 times slower with sulfate than without.