biostudies-literatureUnknown13Sun Wl-Leucine is widely applied in food, feed and medical industries. In this work, an efficient l-leucine producing strain Klebsiella oxytoca LKO-14 was constructed based on an l-valine producer K. oxytoca VKO-9. The exogenous l-leucine biosynthesis pathway was introduced to achieve l-leucine accumulation and decrease l-valine production. Modifying l-leucine transport system and optimizing copy numbers of genes including CgleuA M encoding l-leucine insensitive isopropylmalate synthase, EcleuCD encoding isopropylmalate isomerase, EcleuB encoding isopropylmalate dehydrogenase, NopheDH encoding phenylalanine dehydrogenase, were conducted to increase l-leucine production. The expression of budB encoding α-acetolactate synthSynthetic and systems biotechnology163-171https://www.ebi.ac.uk/biostudies/studies/S-EPMC12907686biostudies-literatureMultistep metabolic engineered Klebsiella oxytoca for efficient l-leucine production.PMC12907686Xu PLiu MKang QLu CSun WKang ZGao CZhou ZMeng WLiu YMa CTan XWang SGong LYang QfalseMultistep metabolic engineered Klebsiella oxytoca for efficient l-leucine production.l-Leucine is widely applied in food, feed and medical industries. In this work, an efficient l-leucine producing strain Klebsiella oxytoca LKO-14 was constructed based on an l-valine producer K. oxytoca VKO-9. The exogenous l-leucine biosynthesis pathway was introduced to achieve l-leucine accumulation and decrease l-valine production. Modifying l-leucine transport system and optimizing copy numbers of genes including CgleuA M encoding l-leucine insensitive isopropylmalate synthase, EcleuCD encoding isopropylmalate isomerase, EcleuB encoding isopropylmalate dehydrogenase, NopheDH encoding phenylalanine dehydrogenase, were conducted to increase l-leucine production. The expression of budB encoding α-acetolactate synth2026-01-01T00:00:00Z2026 Sep2026-07-16T05:17:38.641Z2026-07-09T13:10:20.775ZS-EPMC129076864170446310.1016/j.synbio.2026.01.024