Effect of acetic acid on ethanol production by Zymomonas mobilis mutant strains through continuous adaptation

BMC Biotechnology

Research Article

Yao-Sheng Chang¹  Being-Sun Wung¹  Chia-Wen Hsieh¹  Yu-Fan Liu² 

[1] Department of Microbiology, Immunology and Biopharmaceuticals, National Chiayi University, Chiayi, Taiwan;Division of Allergy, Department of Pediatrics, Chung-Shan Medical University Hospital, Taichung, Taiwan;Department of Biomedical Sciences, College of Medicine Sciences and Technology, Chung Shan Medical University, Taichung, Taiwan;

关键词: Lignocellulosic hydrolysates;    Acetic acid;    Bioethanol;    Zymomonas mobilis;    Acid adaptation;   

DOI  :  10.1186/s12896-017-0385-y

 received in 2017-05-11, accepted in 2017-07-25,  发布年份 2017

来源: Springer

【 摘 要 】

BackgroundAcetic acid is a predominant by-product of lignocellulosic biofuel process, which inhibits microbial biocatalysts. Development of bacterial strains that are tolerant to acetic acid is challenging due to poor understanding of the underlying molecular mechanisms.ResultsIn this study, we generated and characterized two acetic acid-tolerant strains of Zymomonas mobilis using N-methyl-N′-nitro-N-nitrosoguanidine (NTG)-acetate adaptive breeding. Two mutants, ZMA-142 and ZMA-167, were obtained, showing a significant growth rate at a concentration of 244 mM sodium acetate, while the growth of Z. mobilis ATCC 31823 were completely inhibited in presence of 195 mM sodium acetate. Our data showed that acetate-tolerance of ZMA-167 was attributed to a co-transcription of nhaA from ZMO0117, whereas the co-transcription was absent in ATCC 31823 and ZMA-142. Moreover, ZMA-142 and ZMA-167 exhibited a converstion rate (practical ethanol yield to theorical ethanol yield) of 90.16% and 86% at 195 mM acetate-pH 5 stress condition, respectively. We showed that acid adaptation of ZMA-142 and ZMA-167 to 146 mM acetate increased ZMA-142 and ZMA-167 resulted in an increase in ethanol yield by 32.21% and 21.16% under 195 mM acetate-pH 5 stress condition, respectively.ConclusionThe results indicate the acetate-adaptive seed culture of acetate-tolerant strains, ZMA-142 and ZMA-167, could enhance the ethanol production during fermentation.

【 授权许可】

CC BY   
© The Author(s). 2017