Adaptive laboratory evolution of ethanologenic Zymomonas mobilis strain tolerant to furfural and acetic acid inhibitors.
Furfural and acetic acid from lignocellulosic hydrolysates are the prevalent inhibitors to Zymomonas mobilis during cellulosic ethanol production. Developing a strain tolerant to furfural or acetic acid inhibitors is difficul by using rational engineering strategies due to poor understanding of their underlying molecular mechanisms. In this study, strategy of adaptive laboratory evolution (ALE) was used for development of a furfural and acetic acid-tolerant strain. After three round evolution, four evolved mutants (ZMA7-2, ZMA7-3, ZMF3-2, and ZMF3-3) that showed higher growth capacity were successfully obtained via ALE method. Based on the results of profiling of cell growth, glucose utilization, ethanol yield, and activity of key enzymes, two desired strains, ZMA7-2 and ZMF3-3, were achieved, which showed higher tolerance under 7 g/l acetic acid and 3 g/l furfural stress condition. Especially, it is the first report of Z. mobilis strain that could tolerate higher furfural. The best strain, Z. mobilis ZMF3-3, has showed 94.84% theoretical ethanol yield under 3-g/l furfural stress condition, and the theoretical ethanol yield of ZM4 is only 9.89%. Our study also demonstrated that ALE method might also be used as a powerful metabolic engineering tool for metabolic engineering in Z. mobilis. Furthermore, the two best strains could be used as novel host for further metabolic engineering in cellulosic ethanol or future biorefinery. Importantly, the two strains may also be used as novel-tolerant model organisms for the genetic mechanism on the "omics" level, which will provide some useful information for inverse metabolic engineering.
Biogas Institute of Ministry of Agriculture, Biomass Energy Technology Research Centre, Section 4-13, Renming Nanlu, Chengdu, 610041, People's Republic of China.
Zong-Xia
ZX
Shui
Han
H
Qin
Bo
B
Wu
Zhi-yong
ZY
Ruan
Lu-shang
LS
Wang
Fu-Rong
FR
Tan
Jing-Li
JL
Wang
Xiao-Yu
XY
Tang
Li-Chun
LC
Dai
Guo-Quan
GQ
Hu
Ming-Xiong
MX
He
D019342:Acetic Acid / Q000378:metabolism*; D000220:Adaptation, Biological; D000900:Anti-Bacterial Agents / Q000378:metabolism; D004361:Drug Tolerance; D000431:Ethanol / Q000378:metabolism*; D005662:Furaldehyde / Q000378:metabolism*; D008031:Lignin / Q000378:metabolism; D060847:Metabolic Engineering; D017355:Zymomonas / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*
D000900:Anti-Bacterial Agents; C036909:lignocellulose; D000431:Ethanol; D008031:Lignin; D005662:Furaldehyde; D019342:Acetic Acid