Alcohol‐tolerant mutants of cyanobacterium Synechococcus elongatus PCC 7942 obtained by single‐cell mutant screening system

Abstract

Enhancement of alcohol tolerance in microorganisms is an important strategy for improving bioalcohol productivity. Although cyanobacteria can be used as a promising biocatalyst to produce various alcohols directly from CO , low productivity, and low tolerance against alcohols are the main issues to be resolved. Nevertheless, to date, a mutant with increasing alcohol tolerance has rarely been reported. In this study, we attempted to select isopropanol (IPA)-tolerant mutants of Synechococcus elongatus PCC 7942 using UV-C-induced random mutagenesis, followed by enrichment of the tolerant candidates in medium containing 10 g/L IPA and screening of the cells with a high growth rate in the single cell culture system in liquid medium containing 10 g/L IPA. We successfully acquired the most tolerant strain, SY1043, which maintains the ability to grow in medium containing 30 g/L IPA. The photosynthetic oxygen-evolving activities of SY1043 were almost same in cells after 72 h incubation under light with or without 10 g/L IPA, while the activity of the wild-type was remarkably decreased after the incubation with IPA. SY1043 also showed higher tolerance to ethanol, 1-butanol, isobutanol, and 1-pentanol than the wild type. These results suggest that SY1043 would be a promising candidate to improve alcohol production using cyanobacteria. Biotechnol. Bioeng. 2017;114: 1771-1778. © 2017 Wiley Periodicals, Inc.

Effects of <i>n</i>-butanol production on metabolism and the photosystem in <i>Synechococcus elongatus</i> PCC 7942 based on metabolic flux and target proteome analyses

“…The reported BuOH production of the BUOH-SE strain was 317 mg L −1 over 12 days (Lan et al, 2013) and DC11 strain, a further improvement of the BUOH-SE strain, was 418 mg L -1 over 6 days (Fathima et al, 2018). These values corresponded to 12% and 16% of the upper limit concentration of BuOH tolerance in S. elongatus PCC 7942 (Arai et al, 2017;Arsov et al, 2021). In contrast, BuOH-producing Synechocystis sp.…”

Adaptive laboratory evolution of the fast-growing cyanobacterium Synechococcus elongatus PCC 11801 for improved solvent tolerance

“…Cyanobacteria adopt a modified morphology upon excessive light-generated reactive oxygen species (33). S. elongatus PCC 7942 WT when exposed to isopropanol demonstrates elongated morphology (26). However, S. elongatus PCC 11801 WT shows no change in cell morphology when exposed to either 2,3-BD or n-butanol.…”

Beyond the bulk: disclosing the life of single microbial cells

“…Individual mutants of the cyanobacterium Synechococcus elongatus PCC 7942 with beneficial phenotypes, especially a high tolerance against alcohols, were recently identified by Arai et al. ( 2017 ) using a single cell-based screening concept. Synechococcus elongatus PCC 7942 is known to have a generally low tolerance towards alcohols and has consequently not been applied in the production of photobioalcohol from sunlight and CO 2 .…”