INFLUENCE OF FLOW ON ORDERING CHARACTERISTICS OF A BACTERIAL BIOFILM

Freshwater Pseudomonas biofilms were grown on glass plates in a biofil m reactor under various flow rates, Distribution of bacterial orientat ion angle and interbacterial separation distance were presented, The a lignment characteristics of bacteria in the microcolony grown in stati c water extended over a few cells only, When the flow rate was increas ed gradually, the local orientational order developed into a general o rder, However, at the edges of the microcolony, only local order exist ed, On further increasing the flow rate, general order got disrupted a nd showed persistent local alignment of cells, The general order is un derstood to be induced by the shear caused by the flow, At all flow ra tes studied, the microcolony exhibited unique interbacterial separatio n distance distribution, This interbacterial separation distance was t oo large to be explained by the DLVO potential, The non-applicability of this potential to bacteria might be due to the specific forces aris ing from the exopolymeric structures secreted by the Pseudomonas bacte rium.