Inducer expulsion is not a determinant of diauxic growth in Streptococcus bovis.
When Streptococcus bovis JB1 was repeatedly transferred in a medium that contained the non-metabolizable glucose analog, 2-deoxyglucose, it lost its phosphotransferase system (PTS) for glucose but was still able to take up glucose via a facilitated diffusion mechanism. The wild type (JB1) had an inducible enzyme II lactose, but the mutant (JB1(2DG)) had a constitutive lactose PTS. JB1(2DG) was no longer able to exclude lactose when it was provided with glucose, but it retained its ability to expel a non-metabolizable lactose analog. Because JB1(2DG) could utilize glucose and lactose simultaneously and grow in a non-diauxic fashion, it appeared that inducer expulsion was not an important catabolite regulatory mechanism. Based on these results, inducer expulsion may be an artifact of non-metabolizable sugars.
Kearns
D B
DB
Section of Microbiology, Cornell University, Ithaca, NY 14853, USA.
Cook
G M
GM
Russell
J B
JB
D001693:Biological Transport, Active; D003470:Culture Media; D003847:Deoxyglucose; D005947:Glucose / Q000378:metabolism; D007700:Kinetics; D007785:Lactose / Q000378:metabolism; D009154:Mutation; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000235:genetics / Q000378:metabolism; D016985:Streptococcus bovis / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism
D003470:Culture Media; D003847:Deoxyglucose; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; D005947:Glucose; D007785:Lactose