Large inserts for big data: artificial chromosomes in the genomic era.

The exponential increase in available microbial genome sequences coupled with predictive bioinformatic tools is underscoring the genetic capacity of bacteria to produce an unexpected large number of specialized bioactive compounds. Since most of the biosynthetic gene clusters (BGCs) present in microbial genomes are cryptic, i.e. not expressed under laboratory conditions, a variety of cloning systems and vectors have been devised to harbor DNA fragments large enough to carry entire BGCs and to allow their transfer in suitable heterologous hosts. This minireview provides an overview of the vectors and approaches that have been developed for cloning large BGCs, and successful examples of heterologous expression.