Abstract
In spite of the large number of reports on fed-batch cultivation of E. coli, alternative cultivation/induction strategies remain to be more deeply exploited. Among these strategies, it could be mentioned the use of complex media with combination of different carbon sources, novel induction procedures and feed flow rate control matching the actual cell growth rate. Here, four different carbon source combinations (glucose, glycerol, glucose + glycerol and auto-induction) in batch media formulation were compared. A balanced combination of glucose and glycerol in a complex medium formulation led to: fast growth in the batch-phase; reduced plasmid instability by preventing early expression leakage; and protein volumetric productivity of 0.40 g.L-1.h-1. Alternative induction strategies were also investigated. A mixture of lactose and glycerol as supplementary medium fully induced a high biomass population, reaching a good balance between specific protein production (0.148 gprot.gDCW-1) and volumetric productivity (0.32 g.L-1.h-1). The auto-induction protocol showed excellent results on specific protein production (0.158 gprot.gDCW-1) in simple batch cultivations. An automated feed control based on the on-line estimated growth rate was implemented, which allowed cells to grow at higher rates than those generally used to avoid metabolic overflow, without leading to acetate accumulation. Some of the protocols described here may provide a useful alternative to standard cultivation and recombinant protein production processes, depending on the performance index that is expected to be optimized. The protocols using glycerol as carbon source and induction by lactose feeding, or glycerol plus glucose in batch medium and induction by lactose pulse led to rSpaA production in the range of 6 g.L-1, in short fed-batch processes (16 to 20 h) with low accumulation of undesired side metabolites.
Highlights
Swine erysipelas causes great economic losses in swine culture worldwide, and has been controlled by the use of live attenuated or inactivated vaccines (Wood 1992)
Recombinant protein production in E. coli has been extensively investigated, as high cell density da Silva et al SpringerPlus 2013, 2:322 http://www.springerplus.com/content/2/1/322 cultivations (HCDC) employing bioreactors operating in fed-batch mode and using defined medium (Shiloach and Fass 2005; Choi et al 2006; Shojaosadati et al 2008)
HCDC studies usually focus on strategies to achieve high biomass concentrations, whereas the induction is triggered by applying simple techniques, such as addition of IPTG pulse (Babaeipour et al 2007; Carvalho et al 2011; Khalilzadeh et al 2004)
Summary
Swine erysipelas causes great economic losses in swine culture worldwide, and has been controlled by the use of live attenuated or inactivated vaccines (Wood 1992). These formulations offer good levels of protection but can aggravate arthritic problems (Freeman 1964; Wood 1992). The production of recombinant antigenic proteins for subunit formulations is among the technologies proposed for the generation of vaccines (Ashtekar et al 2012). Recombinant protein production in E. coli has been extensively investigated, as high cell density da Silva et al SpringerPlus 2013, 2:322 http://www.springerplus.com/content/2/1/322 cultivations (HCDC) employing bioreactors operating in fed-batch mode and using defined medium (Shiloach and Fass 2005; Choi et al 2006; Shojaosadati et al 2008). Many reports point out for the need to study case by case all these process variables in order to identify the best operation conditions to produce a specific protein
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
