. 2014 Feb 20;5(3):443–447. doi: 10.4161/viru.28196

Table 1. Examples of host vector systems used for functional metagenomic cloning.

Vector	Host(s)	Features	Uses in functional metagenomics
pHT01	E. coli–B. subtilis shuttle vector	This is a shuttle vector containing a colE1 origin of replication for maintenance in E. coli and a B. subtilis theta origin of replication, resulting in relatively stable replication. The plasmid is commercially available from Mo Bi Tec and contains an inducible promoter and blue/white selection for identifying clones. Insert sizes up to 18 kb could be isolated in B. subtilis.	Has been used for screening soil metagenomic libraries for antimicrobial activities²⁹
Bacterial artificial chromosome BAC	E. coli–B. subtilis shuttle vector	These vectors are based on the origin of replication from the E. coli F factor. They can stably replicate large, up to 300 kb, inserts, allowing the isolation of operons and large genetic elements. Several BAC derivatives have been made (see below).
pCC1BAC	E. coli	Can be induced to high copy number and is commercially available from Invitrogen.	Used for cloning large genetic elements and resistance genes³³
pMDB14	E. coli–Pseudomonas putida and S. lividans shuttle vector	A shuttle BAC that can be maintained in at least three different hosts. The library has to be made in E. coli then transferred by conjugation into other hosts. In the non-E. coli hosts the BACs are integrated into the host chromosome which may lead to expression difficulties when screening for some genes.	Allows expression of genes not expressed in E. coli in S. lividans²⁷
pUC family	E. coli	Has a high copy number which can be an advantage when screening for the expression of genes which do not have their own promoter and are not toxic to the host. However can only accept small inserts. This plasmid is commercially available.	Has been used for cloning single antibiotic resistance genes³⁵
Fosmid pM0579	E. coli	Can take inserts of up to 40 kb. The fosmid has been modified to express genes which are not always expressed in E. coli by using the phage T7 promoter to drive expression of the metagenomic DNA and making use of the lambda anti transcription termination protein N so that termination signals within the metagenomic DNA are ignored.	This has allowed the isolated of carbenicillin resistance genes which could not be isolated in the parental fosmid¹⁷