Center for Biofilm Engineering, Montana State University, Bozeman, MT 59717-3980 and Department of Chemical and Biological Engineering, Montana State University, Bozeman, MT 59717-3920, USACenter for Biofilm Engineering, Montana State University, Bozeman, MT 59717-3980 and Department of Chemical and Biological Engineering, Montana State University, Bozeman, MT 59717-3920, USA.