Home - Gene services - Metagenomic / Fosmid / Cosmid

Metagenomic / Fosmid / Cosmid

Fosmid clones are similar in size (ca. 40kb) to cosmids, but, like BAC clones, they contain replicons derived from the F factor for DNA replication and segregation. Because of this property, they are present in low copy number and consequently more stable than cosmids. Also, the copy control vector can be used for easy DNA purification from fosmid clones.

Fosmid libraries are commonly used for closing gaps in a whole genome sequence, physical maping, metagenomic and expression screening and more. Although we greatly prefer to perform the DNA isolation at our facilities we understand that this is not always feasible. Fosmid libraries, contrary to BAC large-insert libraries, do not require HMW DNA (typically 2Mb) as a starting material. This allows scientiststhe needed flexibility in providing DNA to construct a library.

Fosmid library construction details

The key step for fosmid library is preparation of inserts suitable for cloning into the fosmid vector. To achieve true randomness of inserts, our fosmid libraries are generated by random physical shearing of high molecular weight DNA (Please see Figure 1) using proprietary methods. A physically random sheared fosmid library will dramatically reduce the costs for downstream application(s) such as end-sequencing and screening.

Figure 1: Physically sheared HMW DNA (Lane 1: un-sheared, Lanes 2-4: sheared).

Physically sheared HMW DNA

Guaranteed high quality and genome coverage

Proprietary high efficiency cloning methods guarantee high quality and genome coverage that customers need. Obtained inserts sizes are always uniform and range within 35-45Kb (Please see below Figure 2). Our optimized methods are reliable, fast and cost effective.

Figure 2: Size determination of fosmid clones.

Fosmid clones

Versatile Service package available

We offer non-arrayed libraries and arrayed libraries (colony picking, replicate plates, high density filters). We also offer customer library screening for positive clones. Copy control vector can be used for easy DNA purification from fosmid clones.