In sequencing projects, the preparation of templates, involving either the growth of bacteria and subsequent plas-mid purification or the amplification by polymerase chain reaction (PCR) of inserts in vectors (1-3), is one of the most costly steps interms of reagents and time. We have developed a simple method for directly sequencing plas-mids from bacterial colomes that requires only heat-induced lysis of bacterial colonies followed by cycle sequencing (5), thus circumventing template preparation,A related approach using Taq DNA polymerase and [y-~(32)P]ATP-labeled primers has previously been used to determine short sequences (<2'00 bp) (4). In contrast to this, the "colony sequencing" method presented here achieves longer sequences and functions for sequencing by incorporation of [alpha-~(33)P]dATP as well as with fluorescently labeled primers.
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