Cultures were grown overnight in each of the animal-free media types and and 2 l of the overnight culture was added to 200 l of medium in each well of a-we'll Microtest flat bottom,polystyrene plate. The plate was incubated in a SpectraMax plate reader at 30 or 37 depending on the culture. The plate reader was set to shake the plate for 10 s every 20 min to provide increase aeration and cell dispersal. The change in the optical density of each well was measured at 600 nm with readings take every 20 min. Logarithmic growth rate for trplicate cultures were measured using the equation in