title: Biodegradation of tributyl phosphate, an organosphate triester, by aerobic granular biofilms.
abstract: Tributyl phosphate (TBP) is commercially used in large volumes for reprocessing of spent nuclear fuel. TBP is a very stable compound and persistent in natural environments and it is not removed in conventional wastewater treatment plants. In this study, cultivation of aerobic granular biofilms in a sequencing batch reactor was investigated for efficient biodegradation of TBP. Enrichment of TBP-degrading strains resulted in efficient degradation of TBP as sole carbon or along with acetate. Complete biodegradation of 2mM of TBP was achieved within 5h with a degradation rate of 0.4 μmol mL(-1) h(-1). TBP biodegradation was accompanied by release of inorganic phosphate in stoichiometric amounts. n-Butanol, hydrolysed product of TBP was rapidly biodegraded. But, dibutyl phosphate, a putative intermediate of TBP degradation was only partially degraded pointing to an alternative degradation pathway. Phosphatase activity was 22- and 7.5-fold higher in TBP-degrading biofilms as compared to bioflocs and acetate-fed aerobic granules. Community analysis by terminal restriction length polymorphism revealed presence of 30 different bacterial strains. Seven bacterial stains, including Sphingobium sp. a known TBP degrader were isolated. The results show that aerobic granular biofilms are promising for treatment of TBP-bearing wastes or ex situ bioremediation of TBP-contaminated sites.
authors.affiliation: Biofouling and Biofilm Processes Section, Water and Steam Chemistry Division, Chemistry Group, Bhabha Atomic Research Centre, Kalpakkam 603102, Tamil Nadu, India. Electronic address: venkatany@gmail.com.
authors.forename: Y V
authors.initials: YV
authors.lastname: Nancharaiah
authors.affiliation: Biofouling and Biofilm Processes Section, Water and Steam Chemistry Division, Chemistry Group, Bhabha Atomic Research Centre, Kalpakkam 603102, Tamil Nadu, India.
authors.forename: G
authors.initials: G
authors.lastname: Kiran Kumar Reddy
authors.affiliation: Biofouling and Biofilm Processes Section, Water and Steam Chemistry Division, Chemistry Group, Bhabha Atomic Research Centre, Kalpakkam 603102, Tamil Nadu, India.
authors.forename: T V
authors.initials: TV
authors.lastname: Krishna Mohan
authors.affiliation: Biofouling and Biofilm Processes Section, Water and Steam Chemistry Division, Chemistry Group, Bhabha Atomic Research Centre, Kalpakkam 603102, Tamil Nadu, India.
authors.forename: V P
authors.initials: VP
authors.lastname: Venugopalan
mesh_terms: D020001:1-Butanol / Q000737:chemistry; D000085:Acetates / Q000737:chemistry; D000332:Aerobiosis; D001673:Biodegradation, Environmental; D018441:Biofilms; D019149:Bioreactors / Q000382:microbiology*; D010755:Organophosphates / Q000737:chemistry*; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D012722:Sewage / Q000382:microbiology; D042301:Sphingomonadaceae / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D000085:Acetates; D010755:Organophosphates; D012722:Sewage; C065087:di-n-butylphosphoric acid; D020001:1-Butanol; C009524:tributyl phosphate; D010744:Phosphoric Monoester Hydrolases
keywords: Aerobic granular sludge; Aerobic granules; Biodegradation; Phosphatase; Tributyl phosphate