Simultaneous production of poly-γ-glutamic acid and 2,3-butanediol by a newly isolated Bacillus subtilis CS13.
Bacillus subtilis naturally produces large amounts of 2,3-butanediol (2,3-BD) as a main by-product during poly-γ-glutamic acid (γ-PGA) production. 2,3-BD is a promising platform chemical in various industries, and co-production of the two chemicals has great economic benefits. Co-production of γ-PGA and 2,3-BD by a newly isolated B. subtilis CS13 was investigated here. The fermentation medium and culture parameters of the process were optimized using statistical methods. It was observed that sucrose, L-glutamic acid, ammonium citrate, and MgSO4·7H2O were favorable for γ-PGA and 2,3-BD co-production at culture pH of 6.5 and 37 °C. An optimal medium composed of 119.8 g/L sucrose, 48.8 g/L L-glutamic acid, 21.1 g/L ammonium citrate, and 3.2 g/L MgSO4·7H2O was obtained by response surface methodology (RSM). The results show that the titers of γ-PGA and 2,3-BD reached 27.8 ± 0.9 g/L at 24 h and 57.1 ± 1.3 g/L at 84 h with the optimized medium, respectively. γ-PGA and 2,3-BD production by B. subtilis CS13 was significantly enhanced in fed-batch fermentations. γ-PGA (36.5 ± 1.1 g/L, productivity of 1.22 ± 0.04 g/L/h) and 2,3-BD concentrations (119.6 ± 2.8 g/L, productivity of 2.49 ± 0.66 g/L/h) were obtained in the optimized medium with feeding sucrose. The co-production of 2,3-BD and γ-PGA provides a new perspective for industrial production of γ-PGA and 2,3-BD. Key points • A strategy for co-production of γ-PGA and 2,3-BD was developed. • The culture parameters for the co-production of γ-PGA and 2,3-BD were studied. • RSM was used to optimize the medium for γ-PGA and 2,3-BD co-production. • 36.5 g/L γ-PGA and 119.6 g/L 2,3-BD were obtained from the optimum medium in fed-batch fermentation.
['Wang|Dexin|D|', 'Kim|Hyangmi|H|', 'Lee|Sungbeom|S|', 'Kim|Dae-Hyuk|DH|', 'Joe|Min-Ho|MH|https://orcid.org/0000-0001-8786-057X']
D001412:Bacillus subtilis D061249:Batch Cell Culture Techniques D002072:Butylene Glycols D003470:Culture Media D005285:Fermentation D005516:Food Microbiology D018698:Glutamic Acid D007218:Industrial Microbiology D011099:Polyglutamic Acid
Poly-γ-glutamic acid 2,3-Butanediol Bacillus subtilis CS13 Response surface methodology