Genome shuffling enhances stress tolerance of Zymomonas mobilis to two inhibitors

Weiting Wang; Bo Wu; Han Qin; Panting Liu; Yao Qin; Guowei Duan; Guoquan Hu; Mingxiong He

doi:10.1186/s13068-019-1631-4

Genome shuffling enhances stress tolerance of Zymomonas mobilis to two inhibitors

Biotechnol Biofuels. 2019 Dec 16:12:288. doi: 10.1186/s13068-019-1631-4. eCollection 2019.

Authors

Weiting Wang^#^{1

2}, Bo Wu^#¹, Han Qin¹, Panting Liu^{1

2}, Yao Qin^{1

3}, Guowei Duan^{1

2}, Guoquan Hu^{1

2}, Mingxiong He^{1

2}

Affiliations

¹ 1Biomass Energy Technology Research Centre, Key Laboratory of Development and Application of Rural Renewable Energy (Ministry of Agriculture and Rural Affairs), Biogas Institute of Ministry of Agriculture and Rural Affairs, Section 4-13, Renmin Rd. South, Chengdu, 610041 People's Republic of China.
² 2Graduate School of Chinese Academy of Agricultural Science, Beijing, 100081 People's Republic of China.
³ 3College of Pharmacy and Biological Engineering, Chengdu University, Chengdu, 610041 People's Republic of China.

^# Contributed equally.

Abstract

Background: Furfural and acetic acid are the two major inhibitors generated during lignocellulose pretreatment and hydrolysis, would severely inhibit the cell growth, metabolism, and ethanol fermentation efficiency of Zymomonas mobilis. Effective genome shuffling mediated by protoplast electrofusion was developed and then applied to Z. mobilis.

Results: After two rounds of genome shuffling, 10 different mutants with improved cell growth and ethanol yield in the presence of 5.0 g/L acetic acid and 3.0 g/L furfural were obtained. The two most prominent genome-shuffled strains, 532 and 533, were further investigated along with parental strains in the presence of 7.0 g/L acetic acid and 3.0 g/L furfural. The results showed that mutants 532 and 533 were superior to the parental strain AQ8-1 in the presence of 7.0 g/L acetic acid, with a shorter fermentation time (30 h) and higher productivity than AQ8-1. Mutant 533 exhibited subtle differences from parental strain F34 in the presence of 3.0 g/L furfural. Mutations present in 10 genome-shuffled strains were identified via whole-genome resequencing, and the source of each mutation was identified as either de novo mutation or recombination of the parent genes.

Conclusions: These results indicate that genome shuffling is an efficient method for enhancing stress tolerance in Z. mobilis. The engineered strains generated in this study could be potential cellulosic ethanol producers in the future.

Keywords: Electrofusion; Genome shuffling; Inhibitor tolerance; Mutagenesis; Zymomonas mobilis.