DC Field | Value | Language |
---|---|---|
dc.contributor.advisor | Chang, Yong Keun | - |
dc.contributor.advisor | 장용근 | - |
dc.contributor.author | Kim, Yong Jae | - |
dc.date.accessioned | 2021-05-12T19:42:11Z | - |
dc.date.available | 2021-05-12T19:42:11Z | - |
dc.date.issued | 2019 | - |
dc.identifier.uri | http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=913343&flag=dissertation | en_US |
dc.identifier.uri | http://hdl.handle.net/10203/284268 | - |
dc.description | 학위논문(박사) - 한국과학기술원 : 생명화학공학과, 2019.2,[x, 150 p. :] | - |
dc.description.abstract | The processes that produce bio-chemicals from biomasses are sustainable and environmentally friendly methods | - |
dc.description.abstract | however, maximizing sugar utilization is needed for the processes to be more economical. Galactose or xylose is the second most prevalent carbon source present next to glucose according to the kind of biomass. To utilize the three sugars for the production of 2,3-butanediol, Klebsiella oxytoca was used because it can utilize many different substrates in its metabolism. Like other bacteria, the wild type of K.oxytoca assimilates glucose first before utilizing galactose and xylose because of carbon catabolite repression. The sequential utilization of the three sugars lowers the yield and productivity of 2,3-butanediol. In this study, K.oxytoca was genetically engineered to co-utilize the three sugars efficiently. The glucose phosphotransferase system ($PTS^{glc}$), which is the major cause for carbon catabolite repression, was disrupted, and a xylose/$H^+$ symporter was introduced to enhance the consumption rate of the slowest consumed-sugar, xylose. After that, the expression level of glucokinase was modulated, and adaptive laboratory evolution was carried out under a non-metabolizable sugar, 2-deoxy glucose, to recover the diminished glucose consumption rate by the disruption of $PTS^{glc}$. The disruption of $PTS^{glc}$ resulted in simultaneous utilization of 90% galactose and 30% xylose along with glucose, and the co-utilization ratio of xylose was increased to 80% by introducing the xylose/$H^+$ symporter. Adjustment of the glucokinase expression level under a constitutive promoter (J23115) and adaptive evolution led to a 49% recovery of the decreased glucose consumption rate by disruption of the $PTS^{glc}$. Finally, the developed strain showed a 35% and 40% higher overall consumption rate and 2,3-butanediol productivity, respectively, than that of the wild type strain in the three-sugar cultures. The engineered K.oxytoca could serve as a platform for strain development to co-utilize mixed sugars efficiently. In bio-refineries using the hydrolysates of biomasses, mixed sugars can be simultaneously used to produce high value-products such as enzymes and medicines through strain development based on the platform technique. The higher productivity will increase the competitiveness of the whole process. | - |
dc.language | eng | - |
dc.publisher | 한국과학기술원 | - |
dc.subject | Mixed sugar▼aCarbon Catabolite Repression▼aGlucose phosphotransferase system▼aKlebsiella oxytoca▼a2,3-butanediol | - |
dc.subject | 혼합당▼a탄소 이화 작용 산물 억제▼a글루코오스 포스포트랜스퍼라제 시스템▼aKlebsiella oxytoca▼a2,3-butanediol | - |
dc.title | Engineering of Klebsiella oxytoca for simultaneous utilization of multiple sugars | - |
dc.title.alternative | 혼합당 동시 소모를 위한 Klebsiella oxytoca 균주 개발 | - |
dc.type | Thesis(Ph.D) | - |
dc.identifier.CNRN | 325007 | - |
dc.description.department | 한국과학기술원 :생명화학공학과, | - |
dc.contributor.alternativeauthor | 김용재 | - |
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.