Insight into the Genome of Diverse Strains: Specific Genes, Cluster Duplications and DNA Fragment Translocations.

BACKGROUND

There are eighteen species within the genus section , including the original penicillin producers (Fleming strain) and NRRL 1951 Other wild type isolates of the genus are relevant for the production of useful proteins and primary or secondary metabolites. The aim of this article is to characterize strain specific genes and those genes which are involved in secondary metabolite biosynthesis, particularly the mutations that have been introduced during the β-lactams strain improvement programs.

RESULTS

The available genomes of several classical and novel strains have been compared. The first genome sequenced was that of the reference strain Wis54-1255, which derives from the wild type NRRL 1951; its genome size is 32.19 Mb and it encodes 12,943 proteins. Four chromosomes were resolved in and by pulse field gel electrophoresis. The genomes of three industrial strains have a similar size but contain gene duplications and truncations; the penicillin gene cluster copy number ranges from one in the wild type to twelve in the ASPE1 industrial strain and is organized in head to tail tandem repeats. The genomes of two new strains, P. chrysogenum KF-25, a producer of antifungal proteins isolated from a soil sample, and P. chrysogenum HKF2, a strain with carbohydrate-converting activities isolated from a sludge treatment plant, showed strain specific genes.

CONCLUSIONS

The overall comparison of all available P. chrysogenum genomes indicates that there are a significant number of strain-specific genes, mutations of structural and regulatory genes, gene cluster duplications and DNA fragment translocations. This information provides important leads to improve the biosynthesis of enzymes, antifungal agents, prebiotics or different types of secondary metabolites.