Efficient natural plasmid transformation of enables zero-capital molecular biology.

The fast-growing microbe is capable of natural transformation where it draws DNA in from media via an active process under physiological conditions. Using an engineered strain with a genomic copy of the master competence regulator from in combination with a new minimal competence media (MCM) that uses acetate as an energy source, we demonstrate naturally competent cells which are created, transformed, and recovered entirely in the same media, without exchange or addition of fresh media. Cells are naturally competent to plasmids, recombination with linear DNA, and cotransformation of both to select for scarless and markerless genomic edits. The entire process is simple and inexpensive, requiring no capital equipment for an entirely room temperature process (zero capital protocol, 10 cfu/μg), or just an incubator (high-efficiency protocol, 10 cfu/μg). These cells retain their naturally competent state when frozen and are transformable immediately upon thawing like a typical chemical or electrochemical competent cell. Since the optimized transformation protocol requires only 50 min of hands-on time, and grows quickly even on plates, a transformation started at 9 AM yields abundant culturable single colonies by 5 PM. Further, because all stages of transformation occur in the same media, and the process can be arbitrarily scaled in volume, this natural competence strain and media could be ideal for automated directed evolution applications. As a result, naturally competent could compete with as an excellent chassis for low-cost and highly scalable synthetic biology.