Improved electroporation protocol and vectors for Streptococcus bovis

An improved method for electroporation of the ruminal bacterium Streptococcus bovis was developed. The organism was grown aerobically in hyperosmotic medium in the presence of 0.5% (w/v) glycine, and electroporation was carried out in a sucrose-glycerol solution with a field strength of 12.5 kV/cm, 200 Omega resistance and 25 mu F capacitance. Electroporation efficiencies of 0.5 to 2.0 x 10(5) transformants/mu g DNA were achieved. Improved vectors for S. bovis were developed that include a multiple cloning site, and also a promoter region from the S. bovis intracellular amylase gene that may serve as an expression system for foreign genes.