کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
6494208 | 44798 | 2016 | 9 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Production of para-aminobenzoate by genetically engineered Corynebacterium glutamicum and non-biological formation of an N-glucosyl byproduct
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
مهندسی شیمی
بیو مهندسی (مهندسی زیستی)
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
para-Aminobenzoate (PABA), a valuable chemical raw material, can be synthesized by most microorganisms. This aromatic compound is currently manufactured from petroleum-derived materials by chemical synthesis. To produce PABA from renewable resources, its production by fermentation was investigated. The evaluation of the sensitivity to PABA toxicity revealed that Corynebacterium glutamicum had better tolerance to PABA than several other microorganisms. To produce PABA from glucose, genetically engineered C. glutamicum was constructed by introducing both pabAB and pabC. The generated strain produced 20Â mM of PABA in a test-tube scale culture; however, during the investigation, an unidentified major byproduct was detected in the culture supernatant. Unexpectedly, the byproduct was also detected after the incubation of PABA with glucose in a buffer solution without bacterial cells. To elucidate the mechanism underlying the formation of this byproduct, PABA analogues and several kinds of sugars were mixed and analyzed. New chemical compounds were detected when incubating aniline with glucose as well as PABA with reducing sugars (mannose, xylose, or arabinose), indicating that an amino group of PABA reacted non-enzymatically with an aldehyde group of glucose. The molecular mass of the byproduct determined by LC-MS suggested that the molecule was generated from PABA and glucose with releasing a water molecule, generally known as a glycation product. Because the glycation reaction was reversible, the byproduct was easily converted to PABA by acid treatment (around pH 2-3) with HCl. Then, pab genes were screened to improve PABA production. The highest PABA concentration was achieved by a strain expressing the pabAB of Corynebacterium callunae and a strain expressing the pabC of Xenorhabdus bovienii, respectively. A plasmid harboring both the pabAB of C. callunae and the pabC of X. bovienii, the best gene combination, was introduced into a strain overexpressing the genes of the shikimate pathway. The resultant strain produced 45Â mM of PABA in a test-tube scale culture. Under a fermenter-controlled condition, the strain produced up to 314Â mM (43Â g/L) of PABA at 48Â h, with a 20% yield. To our knowledge, this is the highest concentration of PABA produced by a genetically modified microorganism ever reported.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Metabolic Engineering - Volume 38, November 2016, Pages 322-330
Journal: Metabolic Engineering - Volume 38, November 2016, Pages 322-330
نویسندگان
Takeshi Kubota, Akira Watanabe, Masako Suda, Takahisa Kogure, Kazumi Hiraga, Masayuki Inui,