초록
<P><B>Abstract</B></P> <P> <I>Dehalococcoides</I> is able to completely dehalogenate tetrachloroethene (PCE) and trichloroethene (TCE) to ethene (ETH). However, the dechlorination efficiency of <I>Dehalococcoides</I> is low and result in the accumulation of toxic intermediates. In this study, <I>Shewanella oneidensis</I> MR-1 (<I>S. oneidensis</I> MR-1) was added to the <I>Dehalococcoides</I>-containing culture and the complete TCE to ETH dechlorination was shortened from 24 days to 16 days. <I>Dehalococcoides</I>-targeted 16S rRNA gene and two model reductive dehalogenase (RDase) genes (<I>tceA</I> and <I>vcrA</I>), responsible for dechlorinating TCE to vinyl chloride (VC) and VC to ETH respectively, were characterized. Results showed that <I>S. oneidensis</I> MR-1 has no effect on the cell growth while the RDase genes expression was up-regulated and the RDase activity of <I>Dehalococcoides</I> was elevated. The mRNA abundance of <I>vcrA</I> increased approximately tenfold along with the increased concentration of vitamin B<SUB>12</SUB> (cyanocobalamin). Interestingly, the addition of <I>S. oneidensis</I> MR-1 increased the concentration of vitamin B<SUB>12</SUB> by affecting the microbial community structure. Therefore, the addition of <I>S. oneidensis</I> MR-1 might have a positive effect on regulating the activity of RDase of functional microorganisms and uptake of vitamin B<SUB>12</SUB>, and further provided a practical vision of chloroethene dechlorination by the <I>Dehalococcoides</I>–containing culture.</P> <P><B>Highlights</B></P> <P> <UL> <LI> <I>S. oneidensis</I> MR-1 improved dechlorination by a <I>Dehalococcoides</I>-containing culture. </LI> <LI> Adding <I>S. oneidensis</I> MR-1 elevated the reductive dehalogenase genes expression. </LI> <LI> Adding <I>S. oneidensis</I> MR-1 increased the concentration of vitamin B<SUB>12</SUB> in the culture. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>