Transposon mutagenesis in Halomonas eurihalina

We have established a transposon mutagenesis procedure for the moderate hal ophile Halomonas eurihalina, a bacteria that produces an exopolysaccharide (EPS) of considerable biotechnological interest. We used suicide plasmids p UT and pSUP102 to introduce the transposons mini-Tn5 and Tn1732 into H. eur ihalina via Escherichia coli mediated conjugation. Southern hybridization a nalysis demonstrated that insertions of the transposon mini-Tn5 into H. eur ihalina occurred randomly at single sites in the chromosome, whereas Tn1732 insertion also took place at random, but simultaneously, at several sites. Phenotypic analysis revealed that different mutants were generated by usin g mini-Tn5. The isolation of exopolysaccharide-defective strains is the fir st stage towards carrying out genetic studies on EPS production by this mic roorganism. (C) 2000 Editions scientifiques et medicales Elsevier SAS.