สำนักราชบัณฑิตยสภา

The Journal of the Royal Institute of Thailand Vol. 30 No. 1 Jan.-Mar. 2005 58 Humic Substance Enhanced Anaerobic Reduction of Sulfonated Azo Dyes by Paenibacillus sp. Strain A5 Somsak Damronglerd Ò Fellow of the Academy of Science, The Royal Institute, Thailand Nuttapun Supaka Ú Kanchana Juntongjin Û Supat Chareonpornwattana Û Marie-Line Delia Ù Pierre Strehaiano Ù INTRODUCTION Azo dyes are characterized by the presence of one or more azo groups (-N=N-). They are the largest and most versatile class of dyes, and more than half of the annually Abstract The humic quinonemoietymodel compound anthraquinone-2,6-disulfonate (AQDS) could function as redox mediator in the unspecific anaerobic reduction of different industrially relevant sulfonated azo dyes by Paenibacillus sp. strain A5. This compound was enzymatically reduced by the cells of strain A5 to corresponding hydroquinone, which subsequently reduced the azo dyes outside the cells in a purely chemical redox reaction, and ultimately causing decolorization. Cell fractioning experiments demonstrated that the AQDS-dependent azo reductase activity was located in the cell membranes of strain A5. For strain A5, the presence of both membrane-bound and cytoplasmic azo reductase activities was shown, and they were probably different enzyme system, and the former system has significant importance in the reduction of sulfonated azo compounds in vivo, when quinoid redoxmediatorsmay be present. Possible applications of AQDS stimulated anaerobic reduction of azo dyes for the treatment of dye-containing wastewaters are also discussed. Key words : sulfonated azo dyes, azo reductase, anthraquinone-2,6-disulfonate, Paenibacillus sp. Humic Substance Enhanced Anaerobic Reduction of Sulfonated Azo Dyes by Paenibacillus sp. Strain A5 Ò Department of Chemical Technology, Faculty of Science, Chulalongkorn University Ú Program of Biotechnology, Faculty of Science, Chulalongkorn University Û Department of Microbiology, Faculty of Science, Chulalongkorn University Ù Laboratorie de Génie Chimique, INP-ENSIACET, 5, rue Paulin Talabot Site Basso Combo-BP 1301, Toulouse 31106, France produced dyes are azo dyes (62). Presumablymore than 2,000 different azo dyes are currently used for the dyeing of various materials such as textiles, leather, plastics, cosmetics, and food (12). The textile industry consumes the largest amount of azo dyes, and its estimated the approximately 10 - 15% of dyes used for coloring textiles might be lost in waste streams (1). Sulfonated azo dyes are known to be resistant to π‘ æπ∏å µâ π©∫— ∫