An auto-inducible Escherichia coli strain obtained by adaptive laboratory evolution for fatty acid synthesis from ionic liquid-treated bamboo hydrolysate

Qin, Dandan; Hu, Yuanliang; Cheng, Jie; Wang, Nan; Li, Sha; Wang, Dan

doi:10.1016/j.biortech.2016.09.024

Cited by 15 publications

(12 citation statements)

References 36 publications

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“…Additionally, thermophilic communities have been isolated by enriching them for tolerance to [C 2 C 1 Im][OAc], which has resulted in the identification of a mixed population tolerant to 6% w/v [C 2 C 1 Im][OAc] [ 10 ]. Finally, an ALE approach had also been previously employed to develop a strain tolerant to [C 4 C 1 Im]Cl of approximately 7% (w/v) in rich media (LB) [ 11 ]. A direct experimental comparison to two previously developed strains was also conducted.…”

Section: Resultsmentioning

confidence: 99%

“…Thus, an alternate approach to deal with toxicity by developing microbial platform strains that can tolerate residual ILs is needed. Limited tolerance toward ILs has been previously achieved using a range of techniques including rational design [ 8 – 10 ] and adaptive laboratory evolution (ALE) [ 11 ]. The rationally-designed strains generally introduced a non-native efflux pump for ILs which exerts a metabolic burden on the cells and a need for tight expression control.…”

Section: Introductionmentioning

confidence: 99%

“…The rationally-designed strains generally introduced a non-native efflux pump for ILs which exerts a metabolic burden on the cells and a need for tight expression control. The previous ALE study showed promise for the approach [ 11 ], but the scope was limited to one IL, utilized a rich undefined media, and no genetic basis for the improved performance was presented. Nonetheless, this preliminary work revealed an opportunity to apply ALE for IL tolerance and can be used for comparison.…”

Section: Introductionmentioning

confidence: 99%

“…The TALE method differs from previous efforts in that dynamic control is used to increase the amount of stress applied to cells to keep a strong selection pressure without crashing cultures due to overstressed growth conditions. The TALE approach for IL tolerance employed in the present study has two major advantages compared to manual ALE work (e.g., [ 11 ]). First, the TALE approach significantly improved fitness and final cell density in higher IL concentrations than the manual ALE approach.…”

Section: Introductionmentioning

confidence: 99%

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Generation of a platform strain for ionic liquid tolerance using adaptive laboratory evolution

et al. 2017

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BackgroundThere is a need to replace petroleum-derived with sustainable feedstocks for chemical production. Certain biomass feedstocks can meet this need as abundant, diverse, and renewable resources. Specific ionic liquids (ILs) can play a role in this process as promising candidates for chemical pretreatment and deconstruction of plant-based biomass feedstocks as they efficiently release carbohydrates which can be fermented. However, the most efficient pretreatment ILs are highly toxic to biological systems, such as microbial fermentations, and hinder subsequent bioprocessing of fermentative sugars obtained from IL-treated biomass.MethodsTo generate strains capable of tolerating residual ILs present in treated feedstocks, a tolerance adaptive laboratory evolution (TALE) approach was developed and utilized to improve growth of two different Escherichia coli strains, DH1 and K-12 MG1655, in the presence of two different ionic liquids, 1-ethyl-3-methylimidazolium acetate ([C2C1Im][OAc]) and 1-butyl-3-methylimidazolium chloride ([C4C1Im]Cl). For multiple parallel replicate populations of E. coli, cells were repeatedly passed to select for improved fitness over the course of approximately 40 days. Clonal isolates were screened and the best performing isolates were subjected to whole genome sequencing.ResultsThe most prevalent mutations in tolerant clones occurred in transport processes related to the functions of mdtJI, a multidrug efflux pump, and yhdP, an uncharacterized transporter. Additional mutations were enriched in processes such as transcriptional regulation and nucleotide biosynthesis. Finally, the best-performing strains were compared to previously characterized tolerant strains and showed superior performance in tolerance of different IL and media combinations (i.e., cross tolerance) with robust growth at 8.5% (w/v) and detectable growth up to 11.9% (w/v) [C2C1Im][OAc].ConclusionThe generated strains thus represent the best performing platform strains available for bioproduction utilizing IL-treated renewable substrates, and the TALE method was highly successful in overcoming the general issue of substrate toxicity and has great promise for use in tolerance engineering.Electronic supplementary materialThe online version of this article (10.1186/s12934-017-0819-1) contains supplementary material, which is available to authorized users.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Generation of a platform strain for ionic liquid tolerance using adaptive laboratory evolution

et al. 2017

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“…The primary preculture was prepared by inoculating a single colony from a freshly grown plate into 2 mL LB broth supplemented with 100 mg L −1 ampicillin operated 12 h at 250 rpm and 37 °C. The culture was adopted as the seed inoculum to initiate fermentation …”

Section: Methodsmentioning

confidence: 99%

Enhanced 5‐aminovalerate production in Escherichia coli from l‐lysine with ethanol and hydrogen peroxide addition

Cheng

Zhang

Huang

et al. 2018

J of Chemical Tech & Biotech

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BACKGROUND: Increasing environmental and energy concerns are pushing the development of a bio-based economy, employing highly reproducible, sustainable and green biomanufacturing methods. Here a potential building block 5-aminovalerate for polymer synthesis has been produced from L-lysine. RESULTS: L-lysine -oxidase from Scomber japonicas was overexpressed in BL21(DE3); a lysine degradation gene was knocked out to strengthen this process in the microbe. The additions of ethanol and hydrogen peroxide significantly enhanced the production of 5-aminovalerate. The recombinant Escherichia coli CJ02 strain was cultured in a medium containing 20 g L −1 glucose, 10 g L −1 L-lysine, 4% (v/v) ethanol and 10 mM H 2 O 2 , producing 5.61 g L −1 5-aminovalerate with a yield of 0.56 g g −1 . Compared with the original producer, this titre represents an 18-fold increase. Excellently, 29.12 g L −1 5-aminovalerate could be achieved with a yield of 0.44 g g −1 in a 5 L fermenter. CONCLUSION: This biotechnological 5-aminovalerate production demonstrates a simple, economic, and green technology to replace the ubiquitous chemical synthesis. More importantly, this strategy of adding ethanol to increase protein expression is not only an efficient process for the production of 5-aminovalerate, but also might be used in the production of other high value-added chemicals.

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Tolerance improvement of Corynebacterium glutamicum on lignocellulose derived inhibitors by adaptive evolution

Wang

Khushk

Xiao

et al. 2017

Appl Microbiol Biotechnol

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Robustness of fermenting strains to lignocellulose derived inhibitors is critical for efficient biofuel and biochemical productions. In this study, the industrial fermenting strain Corynebacterium glutamicum S9114 was evolved for improved inhibitor tolerance using long-term adaptive evolution by continuously transferring into the inhibitors containing corn stover hydrolysate every 24 h, and finally a stably evolved C. glutamicum was obtained after 128 days of serial transfers. The evolved strain exhibited the highly increased conversion rate to the typical lignocellulose derived inhibitors including furfural, 5-hydroxymethylfurfural, vanillin, syringaldehyde, 4-hydroxybenzaldehyde, and acetic acid. Glucose consumption was obviously accelerated, and 22.4 g/L of glutamic acid was achieved in the corn stover hydrolysate, approximately 68.4% greater than that by the original strain. Whole genome re-sequencing revealed various mutations with the potential connection to the improved performance of the evolved strain. Transcriptional analysis further demonstrated that the glucose-PTS transport and the pentose phosphate pathway were significantly upregulated in the evolved strain, which very likely contributed to the accelerated glucose consumption, as well as sufficient NAD(P)H supply for aldehyde inhibitors reduction conversion and thus enhanced the inhibitor tolerance. This study provided important experimental evidences and valuable genetic information for robust strain construction and modification in lignocellulose biorefining processes.

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An auto-inducible Escherichia coli strain obtained by adaptive laboratory evolution for fatty acid synthesis from ionic liquid-treated bamboo hydrolysate

Cited by 15 publications

References 36 publications

Generation of a platform strain for ionic liquid tolerance using adaptive laboratory evolution

Generation of a platform strain for ionic liquid tolerance using adaptive laboratory evolution

Enhanced 5‐aminovalerate production in Escherichia coli from l‐lysine with ethanol and hydrogen peroxide addition

Tolerance improvement of Corynebacterium glutamicum on lignocellulose derived inhibitors by adaptive evolution

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