초록
<P><B>Background</B></P><P>Arginine is a high-value product, especially for the pharmaceutical industry. Growing demand for environmental-friendly and traceable products have stressed the need for microbial production of this amino acid. Therefore, the aim of this study was to improve arginine production in <I>Escherichia coli</I> by metabolic engineering and to establish a fermentation process in 1-L bioreactor scale to evaluate the different mutants.</P><P><B>Results</B></P><P>Firstly, <I>argR</I> (encoding an arginine responsive repressor protein), <I>speC</I>, <I>speF</I> (encoding ornithine decarboxylases) and <I>adiA</I> (encoding an arginine decarboxylase) were knocked out and the feedback-resistant <I>argA214</I> or <I>argA215</I> were introduced into the strain. Three glutamate independent mutants were assessed in bioreactors. Unlike the parent strain, which did not excrete any arginine during glucose fermentation, the constructs produced between 1.94 and 3.03 g/L arginine. Next, wild type <I>argA</I> was deleted and the gene copy number of <I>argA214</I> was raised, resulting in a slight increase in arginine production (4.11 g/L) but causing most of the carbon flow to be redirected toward acetate. The V216A mutation in <I>argP</I> (transcriptional regulator of <I>argO</I>, which encodes for an arginine exporter) was identified as a potential candidate for improved arginine production. The combination of multicopy of <I>argP216</I> or <I>argO</I> and <I>argA214</I> led to nearly 2-fold and 3-fold increase in arginine production, respectively, and a reduction of acetate formation.</P><P><B>Conclusions</B></P><P>In this study, <I>E. coli</I> was successfully engineered for enhanced arginine production. The <I>∆adiA</I>, <I>∆speC</I>, <I>∆speF</I>, <I>∆argR</I>, <I>∆argA</I> mutant with high gene copy number of <I>argA214</I> and <I>argO</I> produced 11.64 g/L of arginine in batch fermentation, thereby demonstrating the potential of <I>E. coli</I> as an industrial producer of arginine.</P>