초록
<P><B>Abstract</B></P> <P>A typical expression plasmid, pRK415, was widely used to introduce cloned DNA fragment into a broad range of Gram-negative bacteria, including <I>Rhodobacter sphaeroides</I>. Tetracycline (Tc) is required for stable inheritance of the plasmid, but it is subject to photooxidation, inhibitory to the growth of the host strain. However, in this study, the introduction of pRK415 into <I>R. sphaeroides</I> HY01 under tetracycline stress showed clear enhancement on H<SUB>2</SUB> production performance of the recombinant strain pRK415/HY01. The maximum H<SUB>2</SUB> production rate of pRK415/HY01 was enhanced by 10%–70% compared with the control group in the absent of Tc. Supplementing with Tc, the wild type strain HY01 showed repressed cell growth and reduced H<SUB>2</SUB> production performance. The <I>tetAR</I> genes knockout test demonstrated that the expression of <I>tetAR</I> genes on pRK415 promoted the H<SUB>2</SUB> production performance. And within tolerance concentration (Tc < 2.5 mg/L), higher Tc concentration led to higher H<SUB>2</SUB> production performance of pRK415/HY01. Expression of <I>tetAR</I> genes in the genome of <I>R.sphaeroides</I> HY01 by substituting partial of <I>hupSL</I> genes enhanced the H<SUB>2</SUB> production performance as well. The mechanism of the H<SUB>2</SUB> production performance enhancement was discussed.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The pRK415/HY01 showed high H<SUB>2</SUB> production performance under tetracycline (Tc) stress. </LI> <LI> The maximum H<SUB>2</SUB> production rate of pRK415/HY01 was enhanced by 10%–70% under Tc. </LI> <LI> The expression of <I>tetAR</I> induced by Tc promotes H<SUB>2</SUB> production of <I>R. sphaeroides</I> HY01. </LI> </UL> </P>