title: Physiological and Transcriptome Response of the Polycyclic Aromatic Hydrocarbon Degrading Novosphingobium sp. LH128 after Inoculation in Soil.
abstract: Soil bioaugmentation involves the inoculation of pollutant-degrading bacteria to accelerate pollutant degradation. Often the inoculum shows a dramatic decrease in Colony Forming Units (CFU) upon soil inoculation but this behavior is not well-understood. In this study, the physiology and transcriptomic response of a GFP tagged variant of Novosphingobium sp. LH128 was examined after inoculation into phenanthrene spiked soil. Four hours after inoculation, strain LH128-GFP showed about 99% reduction in CFU while microscopic counts of GFP-expressing cells were identical to the expected initial cell density, indicating that the reduction in CFU number is explained by cells entering into a Viable But Non-Culturable (VBNC)-like state and not by cell death. Transcriptome analysis showed a remarkably higher expression of phenanthrene degradation genes 4 h after inoculation, compared to the inoculum suspension concomitant with an increased expression of genes involved in stress response. This indicates that the cells were active in phenanthrene degradation while experiencing stress. Between 4 h and 10 days, CFU numbers increased to numbers comparable to the inoculated cell density. Our results suggest that strain LH128-GFP enters a VBNC-like state upon inoculation into soil but is metabolically active and that VBNC cells should be taken into account in evaluating bioaugmentation approaches.
authors.affiliation: Division of Soil and Water Management, KU Leuven , Kasteelpark Arenberg 20, 3001 Heverlee, Belgium.
authors.forename: Tekle Tafese
authors.identifier: 0000-0003-2223-8522
authors.initials: TT
authors.lastname: Fida
authors.affiliation: Department of Fundamental Microbiology, University of Lausanne, Bâtiment Biophore Quartier Unil-Sorge , 1015 Lausanne, Switzerland.
authors.forename: Silvia K
authors.initials: SK
authors.lastname: Moreno-Forero
authors.affiliation: Division of Soil and Water Management, KU Leuven , Kasteelpark Arenberg 20, 3001 Heverlee, Belgium.
authors.forename: Philip
authors.initials: P
authors.lastname: Breugelmans
authors.affiliation: Department Environmental Biotechnology, Helmholtz Centre for Environmental Research-UFZ , Permoserstrasse 15, 04318 Leipzig, Germany.
authors.forename: Hermann J
authors.initials: HJ
authors.lastname: Heipieper
authors.affiliation: Molecular Cell Physiology, FALW, VU University Amsterdam , De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands.
authors.forename: Wilfred F M
authors.initials: WF
authors.lastname: Röling
authors.affiliation: Division of Soil and Water Management, KU Leuven , Kasteelpark Arenberg 20, 3001 Heverlee, Belgium.
authors.forename: Dirk
authors.initials: D
authors.lastname: Springael
mesh_terms: D001673:Biodegradation, Environmental; D011084:Polycyclic Aromatic Hydrocarbons; D012987:Soil; D012988:Soil Microbiology; D012989:Soil Pollutants; D042301:Sphingomonadaceae / Q000378:metabolism; D059467:Transcriptome
chemical_list: D011084:Polycyclic Aromatic Hydrocarbons; D012987:Soil; D012989:Soil Pollutants