Open AccessMutants of Streptococcus gordonii Challis over-producing glucosyltransferase
Author(s) -
R. J. Haisman,
Howard F. Jenkinson
Publication year - 1991
Publication title -
journal of general microbiology/journal of general microbiology
Language(s) - Uncategorized
Resource type - Journals
eISSN - 2059-9323
pISSN - 0022-1287
DOI - 10.1099/00221287-137-3-483
Subject(s) - glucosyltransferase , mutant , streptococcus gordonii , glucosyltransferases , mutagenesis , biology , biochemistry , microbiology and biotechnology , extracellular , enzyme , strain (injury) , wild type , chemistry , streptococcaceae , gene , anatomy , antibiotics
Two mutants of Streptococcus gordonii which over-produced extracellular polysaccharide when grown on sucrose-containing medium were isolated after mutagenesis of strain Challis with ethyl methanesulphonate. The mutants, designated strains OB20 and OB30, expressed 2.6-fold and 4.7-fold respectively more glucosyltransferase (GTF) activities than the wild-type strain. Transformation experiments suggested that the two mutants carried different mutations, denoted gtf-20 and gtf-30. A double mutant (gtf-20 gtf-30) was constructed and this strain produced 6.4-fold more GTF. Enzymes from wild-type and mutant strains were biochemically indistinguishable and they synthesized structurally identical glucans. Increasing the Na+ concentration of the bacterial growth medium reduced GTF production in all strains by about 60%. Tween 80 also inhibited enzyme production and more specifically reduced GTF synthesis by the mutants. The mutations gtf-20 and gtf-30 appear to define separate genetic loci involved in regulating expression of GTF activity in S. gordonii.