Engineered Zymomonas mobilis tolerant to acetic acid and low pH via multiplex atmospheric and room temperature plasma mutagenesis 06 Biological Sciences 0605 Microbiology

Bo Wu, Han Qin, Yiwei Yang, Guowei Duan, Shihui Yang, Fengxue Xin, Chunyan Zhao, Huanhuan Shao, Yanwei Wang, Qili Zhu, Furong Tan, Guoquan Hu, Mingxiong He

Research output: Contribution to journalArticlepeer-review

41 Scopus citations

Abstract

Background: Cellulosic biofuels are sustainable compared to fossil fuels. However, inhibitors, such as acetic acid generated during lignocellulose pretreatment and hydrolysis, would significantly inhibit microbial fermentation efficiency. Microbial mutants able to tolerate high concentration of acetic acid are needed urgently to alleviate this inhibition. Results: Zymomonas mobilis mutants AQ8-1 and AC8-9 with enhanced tolerance against acetic acid were generated via a multiplex atmospheric and room temperature plasma (mARTP) mutagenesis. The growth and ethanol productivity of AQ8-1 and AC8-9 were both improved in the presence of 5.0-8.0 g/L acetic acid. Ethanol yield reached 84% of theoretical value in the presence of 8.0 g/L acetic acid (~ pH 4.0). Furthermore, a mutant tolerant to pH 3.5, named PH1-29, was generated via the third round of ARTP mutagenesis. PH1-29 showed enhanced growth and ethanol production under both sterilized/unsterilized conditions at pH 4.0 or 3.5. Intracellular NAD levels revealed that mARTP mutants could modulate NADH/NAD + ratio to respond to acetic acid and low pH stresses. Moreover, genomic re-sequencing revealed that eleven single nucleic variations (SNVs) were likely related to acetic acid and low pH tolerance. Most SNVs were targeted in regions between genes ZMO0952 and ZMO0956, ZMO0152 and ZMO0153, and ZMO0373 and ZMO0374. Conclusions: The multiplex mutagenesis strategy mARTP was efficient for enhancing the tolerance in Z. mobilis. The ARTP mutants generated in this study could serve as potential cellulosic ethanol producers.

Original languageEnglish
Article number10
JournalBiotechnology for Biofuels
Volume12
Issue number1
DOIs
StatePublished - 5 Jan 2019

Keywords

  • Acetic acid
  • Inhibitor tolerance
  • Low pH
  • Multiplex atmospheric and room temperature plasma (mARTP)
  • Mutagenesis
  • Zymomonas mobilis

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