title: Aerobic granular sludge mediated biodegradation of an organophosphorous ester, dibutyl phosphite.
abstract: Dibutyl phosphite, an organophosphorous compound, finds applications in different chemical industries and processes. Here, we report an efficient approach of biodegradation to be eventually used in bioremediation of dibutyl phosphite. Aerobic granules capable of dibutyl phosphite biodegradation were cultivated in a sequencing batch reactor (SBR). The SBR was operated with a 24-h cycle by feeding with dibutyl phosphite as a cosubstrate along with acetate. During the course of the SBR operation, aerobic granules of 0.9 ± 0.3 mm size were developed. Complete biodegradation of 1.4, 2 and 3 mM of dibutyl phosphite was achieved in 4, 5 and 8 h, respectively, accompanied by stoichiometric release of phosphite (H3 PO3). Phosphatase activity in the dibutyl phosphite-degrading granular biomass was 3- and 1.5-fold higher as compared to the activated sludge (seed biomass) and acetate-fed aerobic granules, respectively, indicating involvement in the hydrolysis of dibutyl phosphite. Microbial community analysis by t-RFLP showed the presence of 12 different bacterial types. Two bacterial strains capable of growth on dibutyl phosphite as sole carbon source were isolated and characterized as Acidovorax sp. and Sphingobium sp. The results show that aerobic microbial granules based process is suitable for the treatment of dibutyl phosphite contaminated water.
authors.affiliation: Biofouling and Biofilm Processes Section, Water and Steam Chemistry Division, Bhabha Atomic Research Centre, Kalpakkam, India.
authors.forename: G
authors.initials: G
authors.lastname: Kiran Kumar Reddy
authors.forename: Yarlagadda Venkata
authors.initials: YV
authors.lastname: Nancharaiah
authors.forename: Vayalam Purath
authors.initials: VP
authors.lastname: Venugopalan
mesh_terms: D000085:Acetates / Q000378:metabolism; D000332:Aerobiosis; D001419:Bacteria / Q000145:classification / Q000235:genetics; D019149:Bioreactors / Q000382:microbiology; D058448:Biota; D001711:Biotransformation; D004952:Esters / Q000378:metabolism*; D056186:Metagenomics; D010755:Organophosphates / Q000378:metabolism*; D017905:Phosphites / Q000378:metabolism*; D012150:Polymorphism, Restriction Fragment Length; D012722:Sewage / Q000382:microbiology*
chemical_list: D000085:Acetates; D004952:Esters; D010755:Organophosphates; D017905:Phosphites; D012722:Sewage
keywords: aerobic granular sludge; biodegradation; dibutyl phosphite; organophosphorous compounds; phosphatase