초록
<P>Cysteine is a commercially important sulfur-containing amino acid widely used as a supplement in the agricultural and food industries. It is extremely desirable to achieve a high sulfur conversion rate in the fermentation-based cysteine production. Here, the metabolic engineering of <I>Escherichia coli</I> was performed to enhance the sulfur conversion rate in cysteine biosynthesis. Accordingly, the reduction of sulfur loss by the regulator <I>decR</I> and its <I>yhaOM</I> operons were deleted. <I>serACB</I> was integrated into chromosome with constitutive promoter to coordinately increase sulfur utilization. The sulfur assimilation pathways and sulfur transcriptional regulator <I>cysB</I> were overexpressed to regulate sulfur metabolism and enhance sulfur conversion significantly. After the process optimization in fed-batch fermentation, LH16 [SLH02 Δ<I>yhaM</I> Ptrc1-<I>serACB-cysM-nrdH</I>-(pLH03, pTrc99a-<I>cysB</I>)] produced 7.5 g/L of cysteine with a sulfur conversion rate of 90.11%. These results indicate that cysteine production by LH16 is a valuable process in the agricultural and food industries.</P><BR>[FIG OMISSION]</BR>