ORIGINAL PAPER Fed-batch production of a bioflocculant from Corynebacterium glutamicum Haijun Wu • Qingbiao Li • Rui Lu • Yuanpeng Wang • Xiaoling Zhuang • Ning He Received: 24 December 2009 / Accepted: 14 June 2010 / Published online: 30 June 2010 Ó Society for Industrial Microbiology 2010 Abstract The constant-rate fed-batch production of the polygalacturonic acid bioflocculant REA-11 was studied. A controlled sucrose-feeding strategy resulted in a slight improvement in biomass and a 7% reduction in flocculating activity compared with the batch process. When fed with a 3g l -1 urea solution, the flocculating activity was enhanced to 720 U ml -1 in 36 h. High cell density (2.12 g l -1 ) and flocculating activity (820 U ml -1 ) were obtained in a 10-l fermentor by feeding with a sucrose-urea solution, with values of nearly two times and 50% higher than those of the batch process, respectively. Moreover, the residual sucrose declined to 2.4 g l -1 , and residual urea decreased to 0.03 g l -1 . Even higher flocculating activity of 920 U ml -1 and biomass of 3.26 g l -1 were obtained by feeding with a sucrose-urea solution in a pilot scale fermentation process, indicating the potential industrial utility of this constant-rate feeding strategy in bioflocculant production by Corynebacterium glutamicum. Keywords Bioflocculant Á Corynebacterium glutamicum Á Polygalacturonic acid Á Constant-rate feeding Á Flocculation Á Fermentation Abbreviations l Specific cell growth rate q s Specific sucrose consumption rate q p Specific bioflocculant production rate GLC Glucose G6p Glucose-6-phosphate G1P Glucose-1-phosphate UDPG UDP-glucose UDP-GAL UDP-galactose UDP-GALA UDP-galacturonic acid polyGALA Polygalacturonic acid PEP Phosphoenolpyruvate PYR Pyruvic acid AcCoA AcetylCoA ICI Isocitric acid OAA Oxalacetic acid a-KG a-ketoglutaric acid SUC Succinic acid MAL Malic acid LAC Lactic acid AC Acetic acid Introduction The industrial potential of bioflocculants has long been recognized because of their harmlessness, biodegradability and lack of secondary pollution from their degradative intermediates. Considerable scientific attention has been given to this field for nearly 30 years. Although more than 50 microorganisms have been found that produce various types of extracellular bioflocculants [22], none of these have been commercially produced so far. In fact, little H. Wu Á Q. Li Á R. Lu Á Y. Wang Á X. Zhuang Á N. He (&) Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, People’s Republic of China e-mail: hening@xmu.edu.cn Present Address: R. Lu Maternal and Child Health Hospital, Siming District, Xiamen, People’s Republic of China 123 J Ind Microbiol Biotechnol (2010) 37:1203–1209 DOI 10.1007/s10295-010-0767-9