== Effects of propionic acid, butyric acid and lithium chloride on recombinant protein production, cell density, medium acidification and acetate production at 25C cultivations All results were significantly different from the control (P<0.05) hhours,ONovernight,Proppropionic acid,Btbutyric acid;Lilithium chloride Changing the agitation speed can have an impact on growth rate by influencing oxygen transfer through the medium (Henzler and Schedel1991). This study can confirm the viewpoint regarding the harmful effects of acetate on the recombinant protein production GSK583 and cell density. Besides, such methods represent easy and complementary ways to increase target recombinant protein production without negatively affecting host cell density, and requiring complex genetic manipulation. == Electronic supplementary material == The online version of this article (doi:10.1007/s13205-013-0185-6) contains supplementary material, which is available to authorized users. Keywords:Acetate,Escherichia coli, Butyric acid, Lithium chloride, Propionic acid, Recombinant protein == Introduction == A number of bacteria, particularlyEscherichia coli, are common hosts for the expression of a wide variety of recombinant proteins associated with therapeutic, diagnostic and industrial applications. However, in the case ofE. coli, one of the problems during its growth is the reduction and sometimes elimination of recombinant protein production. One of the main reasons for these unfavorable outcomes is the generation of acetic acid as a harmful by-product (Eiteman and Altman2006; Pflug et al.2007). During glucose consumption, bacteria release acetate into the medium. GSK583 It is believed that acetate can have different undesirable effects on bacterial growth and productivity. A rising amount of acetate in the medium causes inhibition of cell growth (Jin et al.2012; Luli and Strohl1990; Roe2002). In fact, the presence of acetate has negative effects on recombinant protein TPOR production (Jensen and Carlsen1990), and by making the environment more acidic might influence bacterial growth (Desvaux2006; Richmond et al.2012). In addition, it has been shown that acetate causes the plasmid copy number in the host to drop off considerably (Cunningham et al.2009; Pan et al.2010). There has been much interest in how GSK583 acetate accumulation can have broad negative effects, such as reduction in the pH of the culture medium. Another effect is the deficiency of certain essential amino acids like methionine (Roe2002) or nucleic acid sources (Cunningham et al.2009; Pan et al.2010). There are currently many efforts being attempted to block the formation of acetate and its release into the media. Industrial strategies tend toward reducing acetate production by the modification of external or internal parameters connected to acetate production. Some of these methods have achieved reduction in acetate production and subsequent increase in recombinant protein production (Aristidou and San1995; De Anda et al.2006; Vemuri et al.2006). The external parameters known as process controlling include medium GSK583 modification, limitation of glucose consumption as well as aeration. For example, controlling glucose consumption rate by complex glucose feeding schemes has successfully reduced acetate accumulation inE. colicultures (Akesson et al.2001; Phue et al.2005; Shiloach et al.1996). The internal genotype of the host cell can also be altered (De Mey et al.2007; Papagianni2012). Some of these approaches include engineering strains to modify the glucose uptake rate (glucose phosphotransferase systemptsG) (De Anda et al.2006; Knabben et al.2011), redirecting the carbon flux toward less inhibitory by-products (e.g., acetoin by acetolactate synthaseals) (Aristidou and San1995), ethanol production through the pet operon (Diaz-Ricci et al.1992; Ingram and Conway1988), storage of excess carbon as glycogen (Dedhia et al.1994) and elimination of the major acetate formation pathway (acetate kinaseackA, phosphotransacetylasepta) (De Mey et al.2007; Phue et al.2010). The objective of this study was to modify the medium content in a simple and moderate way to improve recombinant protein (alpha-synuclein) production without GSK583 negative effects on cell density. Accordingly, propionic acid, butyric acid and lithium chloride were added to the culture media to observe their impact on recombinant protein production and acetate reduction. In fact, propionic acid and lithium chloride are known to act as acetate kinase.
== Effects of propionic acid, butyric acid and lithium chloride on recombinant protein production, cell density, medium acidification and acetate production at 25C cultivations All results were significantly different from the control (P<0
