Two zebra mussel species, Dreissena polymorpha and D. rostriformis bugensis, have invaded North America in the past two decades, with economic impacts totaling billions of dollars to industries that depend on raw water for cooling and/or production.  The patented bacterium, Pseudomonas fluorescens strain CL145A (Pf-CL145A), is being developed as an environmentally benign biological control agent against these aquatic macrofouling pests.  Production of cells that contain the biopesticidal toxin is sensitive to variations in medium composition and fermentation parameters.  Through optimization of the fermentation medium and parameters, toxic cells of Pf-CL145A can consistently be harvested from shake-flasks and 0.5-L and 100-L fermentors.  In addition, we established a low-cost commercial medium formulation from which Pf-CL145A cells can be harvested at a fraction of the previous cost.  Current research efforts are focusing on downstream processing and product formulation as well as toxicity improvements through genetic modifications to develop an economically viable Pf-CL145A-based biocontrol product.