title: Enhanced microbial degradation of humin-bound phenanthrene in a two-liquid-phase system.
abstract: Humin, the main component of soil organic matter, greatly influences the nonlinear sorption and desorption hysteresis of polycyclic aromatic hydrocarbons (PAHs) in soil. However, little is known about the bioavailability of PAHs bound to humin. In the present study, a phenanthrene (PHE)-degrading bacterial strain--PHE9--was isolated and identified as the genus Micrococcus. It was used to investigate the degradation of humin-bound PHE and PHE not bound to humin (non-humin PHE) in liquid mineral medium (MM) and in a two-liquid-phase system (TLPs). The results showed that in MM, about 66.84% of humin-bound PHE was degraded after 49 days, whereas almost all the non-humin PHE was degraded after 27 days. Compared to MM, the TLPs showed a much better efficacy in the removal of PHE, especially for humin-bound PHE: more than 97.28% of non-humin PHE was degraded in 11 days and over 85.62% of humin-bound PHE was degraded in 32 days. It could be concluded that most of humin-bound PHE could be degraded in the MM although humin decreased the bioavailability of PHE, whereas the application of TLPs could enhance the biodegradation of humin-bound PHE.
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China.
authors.forename: Yinping
authors.initials: Y
authors.lastname: Zhang
authors.forename: Fang
authors.initials: F
authors.lastname: Wang
authors.forename: Congying
authors.initials: C
authors.lastname: Wang
authors.forename: Qing
authors.initials: Q
authors.lastname: Hong
authors.forename: Fredrick Orori
authors.initials: FO
authors.lastname: Kengara
authors.forename: Tao
authors.initials: T
authors.lastname: Wang
authors.forename: Yang
authors.initials: Y
authors.lastname: Song
authors.forename: Xin
authors.initials: X
authors.lastname: Jiang
mesh_terms: D001673:Biodegradation, Environmental; D003470:Culture Media; D003627:Data Interpretation, Statistical; D019015:Geologic Sediments / Q000032:analysis; D006207:Half-Life; D006812:Humic Substances / Q000032:analysis*; D008837:Micrococcus / Q000378:metabolism; D010616:Phenanthrenes / Q000737:chemistry / Q000378:metabolism*; D016958:Pseudomonas putida / Q000378:metabolism; D011786:Quality Control; D012989:Soil Pollutants / Q000032:analysis
chemical_list: D003470:Culture Media; D006812:Humic Substances; D010616:Phenanthrenes; D012989:Soil Pollutants; C001861:humin; C031181:phenanthrene