Effect of Plasmid Incompatibility on DNA Transfer to Streptococcus cremoris

Abstract

Several Streptococcus cremoris strains were used in protoplast transformation and interspecific protoplast fusion experiments with Streptococcus lactis and BaciUlus subtilis, with pGKV110, pGKV21, and ApAMIII as the marker plasmids. ApAMIl is a 15.9-kilobase nonconjugative, deletion derivative of pAMI3l, which is considerably larger than the pGKV plasmids (approximately 4.5 kilobases). In general, ApAMjVI was transferred more efficiently than the pGKV plasmids. Using electroporation, we were able to demonstrate that failure of efficient transfer for the pGKV plasmids was, except for one case, caused by incompatibility of these plasmids with resident plasmids of the recipient strain.

Secretion of the rotavirus VP8* protein in Lactococcus lactis

“…Electroporation of L. lactis was carried out as previously described [23]. Competent cells of E. coli were prepared by the RbCl 2 procedure according to Sambrook et al.…”

A possible contribution of mRNA secondary structure to translation initiation efficiency inLactococcus lactis

“…E. coli was transformed according to the protocol of Mandel and Higa [14]. Plasmids were introduced into L. lactis by electroporation [15].…”

Transformation of group A streptococci by electroporation

“…Electroporation was done essentially as described by van der Lelie et al [19]. An overnight culture of Streptococcus pyogenes in Todd Hewitt Broth (Difco, U.S.A.) supplemented with 40 mM dl-threonin was diluted 100-fold in the same medium and grown to an optical density at 650 nm of 0.2 (5 8 x 108 cells per ml).…”

“…cessfully applied to an increasing number of microorganisms [14][15][16][17][18][19][20]. In addition, we show that vectors based on the cryptic Lactococcus lactis subsp, cremoris plasmid pWV01 are able to replicate in group A and H (S. sanguis) streptococci.…”