CELL TRANSFER BY FILTRATION - EVALUATION OF PROTOCOLS FOR TRANSFORMATIONAL COMPETENCE

Collection and washing of cells by centrifugation is a rime consuming and inconvenient component of many microbiological protocols, especial ly when sterility must be maintained. Filtration onto disposable membr ane filters efficiently replaced the centrifugation steps in standard transformational competence protocols for Escherichia coli, Haemophilu s influenzae, and Saccharomyces cerecvisiae. With all three protocols filtered cells were competent sooner and showed transformation efficie ncies comparable to or higher than those of cells prepared by centrifu gation. The procedure can be easily adapted to collect cells for many other purposes: and should be especially useful in metabolic studies a nd in preparing cells for electroporation, as it facilitates both thor ough washing and rapid but gentle resuspension of cells without compro mising sterility.