Microparticle-enhanced production of ε-poly- l -lysine in fed-batch fermentation

• Published in: RSC advances 2015-09, Vol.5 (100), p.82138-82143
• Main Authors: Ren, Xi-Dong, Xu, Yong-Jie, Zeng, Xin, Chen, Xu-Sheng, Tang, Lei, Mao, Zhong-Gui
• Format: Article
• Language: English
• Subjects: Byproducts; Fermentation; Microparticles; Morphology; Pellets; Streptomyces; Talcs
• ISSN: 2046-2069; 2046-2069
• DOI: 10.1039/c5ra14319e

In this study, the effects of talc microparticles on mycelia morphology and epsilon -poly-l-lysine ( epsilon -PL) production by Streptomyces sp. M-Z18 were investigated for the first time. Changing mycelia morphology with talc microparticles has resulted in epsilon -PL production being enhanced. Talc microparticles caused a decrease of pellet diameter from 297.63 plus or minus 156.33 to 205.65 plus or minus 71.56 mu m in shake-flask fermentation. Moreover, the maximum epsilon -PL production reached 2.51 plus or minus 0.08 g L-1 in the presence of 10 g L-1 talc microparticles, which was increased by 50.30%, compared to the control (1.67 plus or minus 0.11 g L-1). The scale-up processes were performed in batch and fed-batch fermentations in a 5 L fermenter with 10 g L-1 talc addition, and the final epsilon -PL production of 30.57 g L-1 was obtained at 168 h, with 44.06% increase over the control. Talc microparticles of 10 g L-1 were then supplied to the fed-batch fermentation with acidic pH shock and agro-industrial by-products, and epsilon -PL production was further increased to 62.36 g L-1 at 192 h, compared to 54.70 g L-1 of the control without supplementary talc. This is also the highest epsilon -PL production reported so far in the literature. These results suggested that talc addition could be an efficient and universal approach for enhancing epsilon -PL production in industry.