TY - CONF

T1 - Extracellular DNA formation during biofilm development by freshwater bacteria

AU - Tang, Lone

AU - Schramm, Andreas

AU - Revsbech, Niels Peter

AU - Neu, Thomas

AU - Meyer, Rikke Louise

PY - 2011/6/30

Y1 - 2011/6/30

N2 - Extracellular DNA (eDNA) has been shown to be important for biofilm formation, both in the initial step of biofilm formation (attachment), and for securing the structural stability of the mature biofilm. It is unclear whether a general consensus exists for when in biofilm formation the presence of eDNA is most important. In this study, we investigated the significance of eDNA during biofilm formation in four freshwater isolates. The aim was to relate the quantity and timing of eDNA production to the isolates’ ability to form biofilms.eDNA and biofilm biomass was quantified over time during biofilm formation in the four environmental isolates: Pseudomonas sp., Serratia sp., Microbacterium sp., and Rheinheimera sp. eDNA was quantified by a novel approach, detecting the fluorescence of PicoGreen® added directly to the biofilm. The isolates Pseudomonas, Serratia and Microbacterium were strong biofilm formers, while Rheinheimera formed little biofilm. Microbacterium produced little eDNA while Pseudomonas, Serratia and Rheinheimera had high eDNA concentrations. However the timing of eDNA production differed between isolates; Pseudomonas biofilms continuously had high concentrations, Serratia had a transient peak at 6 hours, and in Rheinheimera the concentration peaked at 12 hours and remained high. Interestingly, the Rheinheimera biofilm dispersed immediately after the eDNA concentration peaked. The antimicrobial effect of eDNA was tested in growth experiments, and Rheinheimera was strongly affected. Hence biofilm dispersal in Rheinheimera might be due to an antimicrobial effect of eDNA.In conclusion, the significance of eDNA in biofilm development is species specific and much more complex than previously assumed.

AB - Extracellular DNA (eDNA) has been shown to be important for biofilm formation, both in the initial step of biofilm formation (attachment), and for securing the structural stability of the mature biofilm. It is unclear whether a general consensus exists for when in biofilm formation the presence of eDNA is most important. In this study, we investigated the significance of eDNA during biofilm formation in four freshwater isolates. The aim was to relate the quantity and timing of eDNA production to the isolates’ ability to form biofilms.eDNA and biofilm biomass was quantified over time during biofilm formation in the four environmental isolates: Pseudomonas sp., Serratia sp., Microbacterium sp., and Rheinheimera sp. eDNA was quantified by a novel approach, detecting the fluorescence of PicoGreen® added directly to the biofilm. The isolates Pseudomonas, Serratia and Microbacterium were strong biofilm formers, while Rheinheimera formed little biofilm. Microbacterium produced little eDNA while Pseudomonas, Serratia and Rheinheimera had high eDNA concentrations. However the timing of eDNA production differed between isolates; Pseudomonas biofilms continuously had high concentrations, Serratia had a transient peak at 6 hours, and in Rheinheimera the concentration peaked at 12 hours and remained high. Interestingly, the Rheinheimera biofilm dispersed immediately after the eDNA concentration peaked. The antimicrobial effect of eDNA was tested in growth experiments, and Rheinheimera was strongly affected. Hence biofilm dispersal in Rheinheimera might be due to an antimicrobial effect of eDNA.In conclusion, the significance of eDNA in biofilm development is species specific and much more complex than previously assumed.

M3 - Poster

ER -