Cell transfer by filtration: evaluation of protocols for transformational competence.

ABSTRACT

Collection and washing of cells by centrifugation is a time consuming and inconvenient component of many microbiological protocols, especially when sterility must be maintained. Filtration onto disposable membrane filters efficiently replaced the centrifugation steps in standard transformational competence protocols for Escherichia coli, Haemophilus influenzae, and Saccharomyces cerevisiae. With all three protocols filtered cells were competent sooner and showed transformation efficiencies comparable to or higher than those of cells prepared by centrifugation. The procedure can be easily adapted to collect cells for many other purposes, and should be especially useful in metabolic studies and in preparing cells for electroporation, as it facilitates both thorough washing and rapid but gentle resuspension of cells without compromising sterility.