Production of Rhamsan Gum Using a Two-Stage pH Control Strategy by Sphingomonas sp. CGMCC 6833

Appl Biochem Biotechnol (2014) 172:168175

DOI 10.1007/s12010-013-0492-8

Xu Xiao Ying & Zhu Ping & Li Sha & Chen Xiao Ye &

Yao Zhong & Xu Hong

Received: 24 June 2013 /Accepted: 29 August 2013 /

Published online: 21 September 2013# Springer Science+Business Media New York 2013

Abstract In this paper, the production of rhamsan gum from Sphingomonas sp. CGMCC 6833 at different pH values was investigated. Based on kinetic analysis, a two-stage strategy for pH control was proposed. During the first 10 h, pH was controlled at 7.5 to maintain high specific cell growth rate and specific glucose consumption rate. After 10 h, pH decreased naturally to 7.0; this value was retained to maintain high specific rhamsan gum formation rate. Using this method, the maximum concentration and productivity of rhamsan gum reached 18.561.68 g/L and 0.2900.026 g/L/h, which are 12.83 and 12.84 % higher than the optimum results obtained at natural pH, respectively.

Keywords Sphingomonas sp. CGMCC 6833. Rhamsan gum . Two-stage strategy. pHcontrol . Batch fermentation

Introduction

The gellan family is composed of water-soluble exopolysaccharides (EPS) produced by Sphingomonas species; examples of these EPS include gellan gum, welan gum, rhamsan gum, S-657, and S-88 [1]. In general, the backbone structure of these EPS is a repeating linear tetrasaccharide of D-glucose, D-glucuronic acid, and L-rhamnose at a ratio of 2:1:1. Members of the gellan family are widely used as thickening, stabilizing, and suspending agents in various industries, including food [2, 3], pharmaceutical [4], oil field [5, 6], and concrete [7, 8], because of their high viscosity and high stability.

X. X. Ying : Z. Ping : L. Sha : C. X. Ye : Y. Zhong : X. Hong (*)

College of Food Science and Light Industry, State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing University of Technology, No. 30 Puzhu South Road, Pukou District, Nanjing 211800, Chinae-mail: [email protected]

X. X. Ying

College of Food Science and Engineering, Nanjing University of Finance and Economics, Jiangsu key laboratory for grain and oil quality control and further processing technology, No. 3 Wenyuan Road, Qixia District, Nanjing 210023, China

Production of Rhamsan Gum Using a Two-Stage pH Control Strategy by Sphingomonas sp. CGMCC 6833

Appl Biochem Biotechnol (2014) 172:168175 169

Rhamsan gum has the same backbone structure, and each...