Characterization of acetate-resistant mutants of Zymomonas mobilis.

• Main Author: 施龍幃
• Other Authors: Chia-Wen Hsieh
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/98658871269303144172

碩士 === 國立嘉義大學 === 生物醫藥科學研究所(Graduate Institute of Biomedical === 98 === Zymomonas mobilis is the most efficient ethanol producer among the candidates with the production of 1.5-1.9 mol ethanol from each mol glucose, and the production rate is 3-5 fold higher than that of Saccharomyces cerevisiae. However, processes for the hydrolysis of lignocellulosic also produce substances, like as acetic acid is inhibitory to growth and ethanol production of Z. mobilis. The pH value of the ATCC 31821 broth was lower than the acetate-resistant mutants, ATCC 31823 broth, and Z. mobilis ATCC 31823 produced less organic acid than wild-type did in ethanol fermentation medium (10% glucose contained). To addition acetate solution in medium, Z. mobilis ATCC 31823 keep more acid-tolerant in culture. Two dimensional electrophoresis was performed to analysis intracellular prtein expression between these two strains grown with ethanol fermentation medium. Compare with acid-tolerant to wild-type Z. mobilis, 6 and 5 differentially expressed proteins were up-regulation and down-regulation, respectively. We identified these protein spots by MALDI-Q-TOF MS/MS. The 2 proteins, glucokinase (GLK) and pyruvate decarboxylase (PDC) belonged to glucose metabolic pathway, could involve in lowering cytoplasmic acetate levels. The pdc gene of Z. mobilis ATCC 31823 was mutation, include 4 amino acid position opposite in Z. mobilis ATCC 31821, and glk gene nucleotide is all same between these two strains. On the other hand, we use RT-PCR to get glk and pdc gene from Z. mobilis ATCC 31821 and ATCC 31823 mRNA, respectively. It’s confirm these two gene surely expression conformance to protein level. The data demonstrate that GLK and PDC represent regulater for Z. mobilis ATCC 31823 cultured and metabolite produced.