High Fermentative Production ofL-Threonine from Acetate by aBrevibacterium flavumStabilized Strain Transformed with a Recombinant Plasmid Carrying theEscherichia colithr Operon

1 January 1993

journal article
Published by Taylor & Francis in Bioscience, Biotechnology, and Biochemistry

Vol. 57 (10) , 1755-1756
https://doi.org/10.1271/bbb.57.1755

Abstract

Decrease in L-threonine productivity caused not only by plasmid-free segregation but also by plasmid deletion was observed in a Brevibacterium flavum L-threonine producer when transformed with a recombinant plasmid carrying Escherichia coli thr operon. However, a recombinant strain, HT-16, was stabilized by the addition of trimethoprim (a selective marker on the vector) at concentration of 1000 micrograms/ml, which was rather higher than the minimum inhibitory one, into the stock culture medium. Strain HT-16 produced 64.4 g/liter of L-threonine, 30% higher than that of the host strain, after 92 h of cultivation in a small jar fermentor using acetic acid as a carbon source without trimethoprim.

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