Table 2.

Summary of some of the highest reported expression levels of recombinant protein using E. coli

Protein	Molecular Weight (kDa)	Expression level (g/L)	Yield after purification (g/L)	Solubilitya	References
surface protein A from Erysipelothrix rhusiopathiae	42	6.4	n.r	n. r	da Silva et al. [26]
tilapia insulin-like growth factor-2	7	9.7	1.99e	5 M urea (IB)	Hu et al. [37]
human soluble B lymphocyte stimulator	18	3.8	n. r	n. r	Zhang et al. [39]
model cytoplasmic proteinb	n. r	17.6c	n.r	0.1 M Tris–HCl	Kopp et al. [40]
chemotaxis protein CheY fused to green fluorescent protein from Aequorea victoria	n.r	12.0d	n.r	Bug Buster reagent	Wyre et al. [28]
human leptin	16	9.7	3.98e	8 M urea (IB)	Jeong et al. [41]
human interleukin 6	n.r	8.5	n.r	n. r	Tae et al. [38]
phenylalanine dehydrogenase mutant fromTramitichromis intermedius	40	n.r	4.6	20 mM KPi	Zhao et al. [42]
NT*-Bri2 BRICHOS	29.6	18.8	6.5	20 mM Tris- HCl	This study

n.r. – not reported. IB – inclusion bodies

^aRefers to the buffer used to recover the proteins after cell lysis

^bThe exact identity of the model cytoplasmic protein is not reported

^cKopp et al. describe a repetitive fed-batch protocol, in which the expression level is increased after every round. The value here represents the expression level after the first round of fed-batch to make it comparable to the other values reported here. The highest expression level that Kopp et al. reported was 35.5 g/L

^dHighest expression level reported. The highest concentration of soluble protein in the same study was 6 g/L

^eEstimated from the reported % recovery after purification