Efficient biosynthesis of polysaccharide welan gum in heat shock protein-overproducing Sphingomonas sp. via temperature-dependent strategy.

Affiliation

Zhu P(#)(1), Zhan Y(#)(1), Wang C(1), Liu X(1), Liu L(2), Xu H(3).
Author information:
(1)State Key Laboratory of Materials-Oriented Chemical Engineering, College of Food Science and Light Industry, Nanjing Tech University, No.30 South Puzhu Road, Pukou District, Nanjing, 211816, China.
(2)State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, China. [Email]
(3)State Key Laboratory of Materials-Oriented Chemical Engineering, College of Food Science and Light Industry, Nanjing Tech University, No.30 South Puzhu Road, Pukou District, Nanjing, 211816, China. [Email]
(#)Contributed equally

Abstract

Cell growth and product formation are two critical processes in polysaccharide welan biosynthesis, but the conflict between them is often encountered. In this study, a temperature-dependent strategy was designed for two-stage welan production through overexpressing heat shock proteins in Sphingomonas sp. The first stage was cell growth phase with higher TCA cycle activity at 42 °C; the second stage was welan formation phase with higher precursor synthesis pathway activity at 37 °C. The highest welan concentration 37.5 g/L was achieved after two-stage process. Ultimately, this strategy accumulated welan yield of 79.2 g/100 g glucose and productivity of 0.62 g/L/h at 60 h, which were the best reported results so far. The duration of fermentation was shortened. Besides, rheological behavior of welan gum solutions remained stable at wide range of temperature, pH, and NaCl. These results indicated that this approach efficiently improved welan synthesis.