Inhibition of the Reattachment of Zebra Mussels (Dreissenapolymorpha) by Biofilms of Bacillus sp., strain JK1

Alexander B. Stegeman
Carroll College 
Mentor:  Dr. James Maki

Biofilms of Bacillus sp. JK1, have been previously shown to inhibit zebra mussel reattachment.  To determine if cells needed to be alive to cause inhibition, biofilms were treated either with 1500µJcm-2 UV light or 4% paraformaldehyde in order to kill the cells.  The reattachment of zebra mussels was then compared for living and dead biofilms.  There was no difference (P>0.05, ANOVA) between controls and all treatments for biofilms developed on glass Petri dishes.  In 2 out of 3 trials, there was a difference (P<0.05, ANOVA and Tukey test) between controls and at least one of the treatments for biofilms developed on polystyrene Petri dishes.  The data suggest that biofilms of this bacterium may not need to be alive to inhibit reattachment.  Exopolymers isolated from biofilms developed on glass Petri dishes and adsorbed to nylon filters (Nytran) stimulated mussel reattachment when compared to Nytran controls (P<0.05, Tukey test).  Exopolymers isolated from biofilms developed on polystyrene Petri dishes and adsorbed to the nylon filters had no affect on mussel reattachment when compared to Nytran controls (P>0.05, Tukey test).  The results suggest that both living and dead biofilms of this bacterium have the same affect on zebra mussel reattachment, and that exopolymers from biofilms on glass may enhance mussel reattachment. 
 

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