NOVEL NARROW-HOST-RANGE VECTORS FOR DIRECT CLONING OF FOREIGN DNA IN PSEUDOMONAS

Narrow-host-range vectors, based on an indigenous replicon and contain ing a multiple cloning site, have been constructed in a Pseudomonas ho st capable of growth on unusual substrates. The new cloning vectors yi eld sufficient amounts of DNA for preparative purposes and belong to a n incompatibility group different from that of the incP and incQ broad -host-range vectors. One of these vectors, named pDB47F, was used to c lone, directly in Pseudomonas, DNA fragments from Agrobacterium, Pseud omonas, and Rhizobium. A clone containing Agrobacterium and Km(R) gene sequences was transformed with a higher efficiency than an RSF1010-de rived vector (by as much as 1250-fold) in four out of five Pseudomonas strains tested. The considerable efficiency obtained with this system makes possible the direct cloning and phenotypic selection of foreign DNA in Pseudomonas.