http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Sathesh-Prabu, Chandran,Lee, Sung Kuk American Chemical Society 2015 Journal of agricultural and food chemistry Vol.63 No.37
<P>Long-chain α,ω-dicarboxylic acids (LDCAs, ≥C12) are widely used as a raw material for preparing various commodities and polymers. In this study, a CYP450-monooxygenase-mediated ω-oxidation pathway system with high ω-regioselectivity was heterologously expressed in <I>Escherichia coli</I> to produce DCAs from fatty acids. The resulting engineered <I>E. coli</I> produced a maximum of 41 mg/L of C12 DCA and 163 mg/L of C14 DCA from fatty acids (1 g/L), following 20 h of whole cell biotransformation. Addition of a heme precursor and the hydroxyl radical scavenger, thiourea, increased product concentration (159 mg/L of C12 DCA and 410 mg/L of C14 DCA) in a shorter culture duration than that of the corresponding controls. DCAs of various chain lengths were synthesized from coconut oil hydrolysate using the engineered <I>E. coli</I>. This novel synthetic biocatalytic system could be applied to produce high value DCAs in a cost-effective manner from renewable plant oils.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jafcau/2015/jafcau.2015.63.issue-37/acs.jafc.5b03833/production/images/medium/jf-2015-03833u_0008.gif'></P>
SATHESH-PRABU CHANDRAN,Sung Kuk LEE 한국생물공학회 2021 한국생물공학회 학술대회 Vol.2021 No.4
Recent biotechnological progress, particularly in the areas of genetic/genomic engineering, synthetic biology, systems biology, and metabolic engineering, offers novel tools to customize cell factories for bio-based production. The production of bio-based bulk chemicals from renewable bioresources has gained great attention in the scientific community as the process could avoid and/or minimize the negative impacts of the conventional chemical-based productions on the environment and depleting resources of natural petrochemicals. An inducible promoter is a crucial component for microbial-based chemical production. The induction of promoter expression by the addition of chemical inducers such IPTG is considered the most efficient method. However, it has the following limitations, such as the requirement of cell growth monitoring for the addition of chemical inducers at the optimal cell density, not feasible with industrial scale-up, and undesirable because of its toxicity and cost. Moreover, constitutive expression or strong expression of synthetic pathway genes can cause growth inhibition, less glucose consumption, and reduce product yield. Thus, inexpensive carbon source- or substrate-inducible systems are considered as one of the efficient systems for biosynthesis of chemicals, especially at industrial scale. 2,3-Butanediol (BDO), an important platform chemical, has many industrial applications and is used as a solvent, a high-grade aviation fuel because of its high-octane number, and a precursor of many synthetic polymers and resins. In addition, BDO is used in the manufacture of perfumes, fumigants, printing inks, moistening and softening agents, antifreeze, lubricants, fuel additives, explosives, plasticizes, and pharmaceutical carriers. In the present study, a glucose-inducible gene expression system has been developed using HexR-P<sub>zwf1</sub> of Pseudomonas putida to induce the metabolic pathways. Since the system is controlled by an Entner–Doudoroff pathway (EDP) intermediate, the EDP of Escherichia coli was activated by deleting pfkA and gntR genes. Growth experiment with GFP as a reporter indicated that the induction of this system was tightly controlled over a wide range of glucose in E. coli without adding any inducer. 2,3-butanediol (BDO) synthetic pathway genes were expressed by this system in the pfkA-gntR-deleted strain. The resultant engineered strain harbouring this system efficiently produced BDO with a 71% increased titer than the control strain. The strain was also able to produce BDO from a mixture of glucose and xylose which is comparable to glucose alone. Further, the strain produced 11 g/L of BDO at a yield of 0.48 g/g from the hydrolysate of empty palm fruit bunches. This system can also be applied in many other bio-production processes from lignocellulosic biomass.
Carbon Source- or Substrate- Inducible Promoter Systems for Pseudomonas putida KT2440
Sathesh-Prabu CHANDRAN,Sung Kuk LEE 한국생물공학회 2021 한국생물공학회 학술대회 Vol.2021 No.10
The production of biobased bulk chemicals from renewable bioresources could minimize the negative impacts of conventional chemical-based productions on the environment and the challenges posed by depleting resources of natural petrochemicals. Pseudomonas putida strain KT2440 is a prominent metabolic engineering and synthetic biology chassis for industrial and medical applications because of its robustness and metabolic versatility. Inducible and tuneable expression systems are essential for microbial production of biochemicals. Here, carbon source- or substrate- inducible promoter systems for P. putida KT2440 strain were developed. The systems can be induced by the low-cost substrates such as glucose, xylose, levulinic acid and 3-hydroxypropionic acid. These substrates can be used as the potent starting material for both cell growth and production of a wide range of biochemicals. The systems are tuneable and controllable. LvaR/PlvaA and XutR/PxutA systems were sensitive even at low concentration of levulinic acid (0.1 mM) and xylose (0.5 mM), respectively. As the efficiency of the reported systems were very much comparable with the conventional chemical inducible systems, their limitations such as high cost, cell toxicity and difficulties in downstream process could be avoided. Hence, the newly investigated promoter systems are highly useful for the expression of the target genes in the widely used synthetic biology chassis Pseudomonas putida KT2440 for industrial and medical applications.