title: An investigation of anthraquinone dye biodegradation by immobilized Aspergillus flavus in fluidized bed bioreactor.
abstract: OBJECTIVE
  Biodegradation and biodecolorization of Drimarene blue K(2)RL (anthraquinone) dye by a fungal isolate Aspergillus flavus SA2 was studied in lab-scale immobilized fluidized bed bioreactor (FBR) system.
  
  
  METHODS
  Fungus was immobilized on 0.2-mm sand particles. The reactor operation was carried out at room temperature and pH 5.0 in continuous flow mode with increasing concentrations (50, 100, 150, 200, 300, 500 mg l(-1)) of dye in simulated textile effluent on the 1st, 2nd, 5th, 8th, 11th, and 14th days. The reactors were run on fill, react, settle, and draw mode, with hydraulic retention time (HRT) of 24-72 h. Total run time for reactor operation was 17 days.
  
  
  RESULTS
  The average overall biological oxygen demand (BOD), chemical oxygen demand (COD), and color removal in the FBR system were up to 85.57%, 84.70%, and 71.3%, respectively, with 50-mg l(-1) initial dye concentration and HRT of 24 h. Reductions in BOD and COD levels along with color removal proved that the mechanism of biodecolorization and biodegradation occurred simultaneously. HPLC and LC-MS analysis identified phthalic acid, benzoic acid, 1, 4-dihydroxyanthraquinone, 2,3-dihydro-9,10-dihydroxy-1,4-anthracenedione, and catechol as degradation products of Drimarene blue K(2)RL dye. Phytotoxicity analysis of bioreactor treatments provided evidence for the production of less toxic metabolites in comparison to the parent dye.
  
  
  CONCLUSIONS
  The present fluidized bed bioreactor setup with indigenously isolated fungal strain in its immobilized form is efficiently able to convert the parent toxic dye into less toxic by-products.
authors.affiliation: Department of Microbiology, Quaid-i-Azam University, Islamabad, Pakistan. saadiamarwat@yahoo.com
authors.forename: Saadia
authors.initials: S
authors.lastname: Andleeb
authors.forename: Naima
authors.initials: N
authors.lastname: Atiq
authors.forename: Geoff D
authors.initials: GD
authors.lastname: Robson
authors.forename: Safia
authors.initials: S
authors.lastname: Ahmed
mesh_terms: D000880:Anthraquinones / Q000378:metabolism* / Q000633:toxicity; D001231:Aspergillus flavus / Q000235:genetics / Q000378:metabolism*; D019817:Benzoic Acid / Q000378:metabolism; D057919:Biological Oxygen Demand Analysis; D019149:Bioreactors / Q000382:microbiology*; D002396:Catechols / Q000378:metabolism; D018914:Cells, Immobilized; D002851:Chromatography, High Pressure Liquid; D004396:Coloring Agents / Q000378:metabolism*; D004867:Equipment Design; D008129:Lolium / Q000187:drug effects; D008969:Molecular Sequence Data; D010795:Phthalic Acids / Q000378:metabolism; D010802:Phylogeny; D011743:Pyrimidines / Q000378:metabolism; D013783:Textile Industry; D018675:Toxicity Tests; D014753:Vinyl Compounds / Q000378:metabolism* / Q000633:toxicity; D014865:Waste Disposal, Fluid / Q000295:instrumentation / Q000379:methods*
chemical_list: D000880:Anthraquinones; D002396:Catechols; D004396:Coloring Agents; D010795:Phthalic Acids; D011743:Pyrimidines; D014753:Vinyl Compounds; C575089:drimarene blue K2RL; C069622:Drimarene brilliant blue; C032279:phthalic acid; C034890:1,4-dihydroxyanthraquinone; D019817:Benzoic Acid; C034221:catechol