Engineering Corynebacterium glutamicum for the de novo biosynthesis of tailored poly-γ-glutamic acid.
Metab Eng
; 56: 39-49, 2019 12.
Article
em En
| MEDLINE
| ID: mdl-31449877
ABSTRACT
γ-Polyglutamic acid (γ-PGA) is a biodegradable polymer naturally produced by Bacillus spp. that has wide applications. Fermentation of γ-PGA using Bacillus species often requires the supplementation of L-glutamic acid, which greatly increases the overall cost. Here, we report a metabolically engineered Corynebacterium glutamicum capable of producing γ-PGA from glucose. The genes encoding γ-PGA synthase complex from B. subtilis (pgsB, C, and A) or B. licheniformis (capB, C, and A) were expressed under inducible promoter Ptac in a L-glutamic acid producer C. glutamicum ATCC 13032, which led to low levels of γ-PGA production. Subsequently, C. glutamicum F343 with a strong L-glutamic acid production capability was tested. C. glutamicum F343 carrying capBCA produced γ-PGA up to 11.4â¯g/L, showing a higher titer compared with C. glutamicum F343 expressing pgsBCA. By introducing B. subtilis glutamate racemase gene racE under Ptac promoter mutants with different expression strength, the percentage of L-glutamic acid units in γ-PGA could be adjusted from 97.1% to 36.9%, and stayed constant during the fermentation process, while the γ-PGA titer reached 21.3â¯g/L under optimal initial glucose concentrations. The molecular weight (Mw) of γ-PGA in the engineered strains ranged from 2000 to 4000â¯kDa. This work provides a foundation for the development of sustainable and cost-effective de novo production of γ-PGA from glucose with customized ratios of L-glutamic acid in C. glutamicum.
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Texto completo:
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Ácido Poliglutâmico
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Corynebacterium glutamicum
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Engenharia Metabólica
Idioma:
En
Ano de publicação:
2019
Tipo de documento:
Article