글리세롤을 이용한 Klebsiella pneumoniae GEM167의 1,3-부탄디올 생산 연구 = Study on 1,3-butanediol production from glycerol by Klebsiella pneumoniae GEM167

다국어 초록 (Multilingual Abstract)

1,3-Butanediol (1,3-BDO) is a C4 diol that serves as a versatile platform chemical for producing various industrial materials and consumer products. The 1,3-BDO is not naturally produced in the microorganism, an artificial phaA-dependent pathway consisting of phaA, phaB, bld, and yqhD was introduced to establish de novo 1,3-BDO biosynthesis, resulting in a titer of 0.35 ± 0.11 g/L after 24 h. In Klebsiella pneumoniae GEM167 ΔadhEΔldhAΔbudA/pACYC171-bld-phaA-phaB-yqhD, where the major by-product pathways for ethanol, lactic acid, and 2,3-butanediol were deleted, the 1,3-BDO concentration increased to 1.72 ± 0.14 g/L, representing a 4.9-fold improvement. Optimization of bioprocess parameters, specifically agitation speed at 500 rpm and pH 6.5, further enhanced production to 3.75 ± 0.16 g/L at 36 h in fed-batch. Furthermore, when crude glycerol was used as the sole carbon substrate, the maximum 1,3-BDO titer reached 3.92 ± 0.23 g/L at 30 h. These results demonstrate the potential of crude glycerol as a sustainable and cost-effective substrate for microbial 1,3-BDO production, highlighting its applicability in industrial bioprocesses.

목차 (Table of Contents)

• 1. Introduction 1
• 2. Materials and methods 6
• 2.1. Strains and plasmids 6
• 2.2. Knockout of genes in K. pneumoniae GEM167 6
• 2.3. Construction of recombinant plasmids 7
• 2.4. Pre-culture medium and condition 9
• 2.5. Fermentor culture medium 9
• 2.6. Fed-batch fermentation by the recombinant K. pneumoniae GEM167 10
• 2.7. Analytic method 11
• 3. Results and discussion 18
• 3.1. Construction of a biosynthetic pathway for production of 1,3-BDO from glycerol in K. pneumoniae GEM167 18
• 3.2. Enhancement of 1,3-BDO production via deletion of major by-product pathway 25
• 3.3. Effect of bioprocess factors on 1,3-BDO production 31
• 3.4. Redirection of carbon flux toward 1,3-BDO by gene knockout of acetic acid pathway 36
• 3.5. Relief of pyruvate accumulation for enhanced of 1,3-BDO production 40
• 3.6. Comparison of pure and crude glycerol for 1,3-BDO production 43
• 4. Conclusion 47
• References 48