Open AccessL-(+)-lactate dehydrogenase deficiency is lethal in Streptococcus mutans
Author(s) -
Anping Chen,
Jeffrey D. Hillman,
Marilyn J. Duncan
Publication year - 1994
Publication title -
journal of bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.652
H-Index - 246
eISSN - 1067-8832
pISSN - 0021-9193
DOI - 10.1128/jb.176.5.1542-1545.1994
Subject(s) - thermolabile , biology , streptococcus mutans , lactate dehydrogenase , escherichia coli , microbiology and biotechnology , gene , enzyme , biochemistry , genetics , bacteria
The previously cloned gene for L-(+)-lactate dehydrogenase (LDH) from Streptococcus mutans was mutagenized in vitro. An Escherichia coli transformant which expressed a thermolabile LDH activity was identified. The ldh(Ts) gene was introduced into S. mutans on a suicide vector to create a heterodiploid expressing both wild-type and thermolabile LDH activities. Self-recombinants which had only one ldh gene were isolated. One of these clones expressed only the thermolabile LDH activity. This isolate grew well at 30 degrees C but did not grow at 42 degrees C under a variety of cultivation conditions, thereby proving that LDH deficiency is lethal in S. mutans in the absence of compensatory mutations.