中国科学院过程工程研究所机构知识库

beta-Poly(malic acid) (PMLA) has attracted increasing attentions because of its potential application in medicine and other industries. In this study, the variation of PMLA molecular weight (M-w) in the batch culture and the strategies to enhance PMLA M-w were studied. Adding exogenous Ca2+ (0.1 g/L CaCl2) to the medium caused a significant increase in both PMLA concentration and M-w (11.38% and 26.3%, respectively) when Na2CO3 was used as the neutralizer. The M-w of PMLA during the process of batch culture, which associated with the specific PMLA production per unit cell mass (Y-p/x) before glucose was depleted, increased from 12.522KDa to its maximum 18.693KDa and then kept decreasing until the end of the culture. Compared with the results in batch culture, M-w increased by 84.4% (up to 19.51 kDa) with a productivity of 1.1 gh(-1) L-1 when the cells were maintained in exponential growth phase during Ca2+ added repeated batch culture. The present work provides an efficient approach to obtain superior quality PMLA product with high M-w. (C) 2015 Elsevier B.V. All rights reserved.