Abstract
An efficient method for the isolation of dihydrodipicolinate synthase (DPS)-defective threonine producers from a Br evibacterium strain with feedback-sensitive aspartokinase (AK, Aks) was established. After mutagenesis of a strain with AK, No. 70, mutants resistant to α-amino-β- hydroxyvaleric acid were isolated and then selected as to threonine productivity in the presence of diaminopimelic acid. DPS activity in the strains in which the threonine production was inhibited by lysine was found to be absent or reduced to less than 10 % of the level in the parent. On the other hand, the strains in which the production was not inhibited by lysine were conventional threonine producers with feedback-resistant homoserine dehydrogenases (HDs and HDRs) and wild type DPS. The HD activities of most of the threonine mutants were also markedly reduced. However, only one mutant lacking DPS, DK330, exhibited an HD level comparable to that in the parent and produced the largest amount of threonine among the threonine prod...
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
