title: Kinetics of carbon sharing in a bacterial consortium revealed by combining stable isotope probing with fluorescence-activated cell sorting.
abstract: OBJECTIVE
  To determine the kinetics of substrate fluxes in a microbial community in order to elucidate the roles of the community members.
  
  
  RESULTS
  The kinetics of substrate sharing in a bacterial consortium were measured by a new analytical approach combining immunostaining, stable isotope probing and fluorescence-activated cell sorting (FACS). The bacterial consortium, consisting of four strains and growing on 4-chlorosalicylate (4-CS), was pulse-dosed with the degradation intermediate [U-(13) C]-4-chlorocatechol (4-CC). Cells were stained with strain-specific antibodies sorted by FACS and the (13) C-incorporation into fatty acids of the two most abundant members of the community was determined by isotope ratio mass spectrometry. From the two most abundant strains, the primary degrader Pseudomonas reinekei MT1 incorporated the labelled substrate faster than strain Achromobacter spanius MT3 but the maximal incorporation in strain MT3 was almost three times higher than in MT1.
  
  
  CONCLUSIONS
  It has been reported that strain MT1 produces 4-CC as an intermediate but has a lower LD50 for it than strain MT3; therefore, MT3 still degrades 4-CC when the concentrations of 4-CC are already too toxic, even lethal, for MT1. By degrading 4-CC, produced by MT1, MT3 protects the entire community against this toxin. The higher affinity but lower tolerance of strain MT1 for 4-chlorocatechol compared to strain MT3 explains the complementary function these two strains have in the consortium adding exceptional stability to the entire community.
  
  
  CONCLUSIONS
  The novel approach can reveal carbon fluxes in microbial communities generating quantitative data for systems biology of the microbial community.
authors.affiliation: Helmholtz Center for Infection Research, Chemical Microbiology, Braunschweig, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Pawelczyk
authors.forename: D
authors.initials: D
authors.lastname: Bumann
authors.forename: W-R
authors.initials: WR
authors.lastname: Abraham
mesh_terms: D001419:Bacteria / Q000302:isolation & purification / Q000378:metabolism*; D002244:Carbon / Q000378:metabolism*; D002247:Carbon Isotopes; D002396:Catechols / Q000378:metabolism; D005434:Flow Cytometry; D007700:Kinetics; D013058:Mass Spectrometry; D059013:Microbial Consortia; D008969:Molecular Sequence Data; D011549:Pseudomonas / Q000378:metabolism; D012459:Salicylates / Q000378:metabolism
chemical_list: D002247:Carbon Isotopes; D002396:Catechols; D012459:Salicylates; C479918:4-chlorosalicylic acid; D002244:Carbon; C038861:4-chlorocatechol