Prospects for the genetic manipulation of lactobacilli

Abstract Efforts are underway in a number of laboratories around the world to develop methods for the improvement of Lactobacillus strains by recombinant DNA techniques. Research has centered on: (i) characterization and construction of chimeric shuttle vectors based on endogenous Lactobacillus plasmids which are capable of replicating in lactobacilli; (ii) molecular cloning of genes and operons from lactobacilli encoding important pathways such as the lactose : phospho enol pyruvate phosphotransferase system, phosphogalactoside-β- d -galactohydrolase, and β-galactosidase; and (iii) methods for introduction of genes in vivo and in vitro through conjugation, transfection and transformation. The lack of natural gene exchange systems has prompted research efforts to devise a protoplast transformation system. Initial early successes in gene cloning, vector development, transfection, conjugation, protoplast fusion and, recently, transformation, have laid the ground-work for rapid development of gene exchange systems for the genus.