초록
<P><B>Abstract</B></P> <P>To enrich polyhydroxyalkanoate (PHA) producing microbial communities, generally, a feast-famine regime is applied. Here we investigated the impact of continuous substrate feeding on the enrichment of PHA-producing bacteria in two sequencing batch reactors (SBRs). In the first reactor, the substrate (acetate) was dosed continuously and <I>Zoogloea</I> sp. was enriched. The culture accumulated PHA upon exposure to excess carbon, but the PHA production rate and storage capacity (53 wt.%) were one-fifth of that observed for enrichment cultures in a standard, pulse-fed SBR dominated by the PHA producer <I>Plasticicumulans acidivorans</I>. In the second reactor, half the acetate was dosed at the beginning of the cycle and the other half continuously. Having a true feast phase, the enrichment of <I>P. acidivorans</I> was not impeded by the continuous supply of acetate and the culture accumulated 85 wt.% PHA. This shows that for the enrichment of bacteria with a superior PHA-producing capacity periodic substrate excess – a true feast phase – is essential, while periodic substrate absence – a true famine phase – is not.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Two continuously-fed SBRs to study the impact of the absence of a famine phase. </LI> <LI> When all acetate fed continuously; <I>Zoogloea</I> sp. enriched and 53 wt.% PHA stored. </LI> <LI> When half the acetate fed as pulse; <I>P. acidivorans</I> enriched and 85 wt.% PHA stored. </LI> <LI> Enrichment of PHA producer <I>P. acidivorans</I> not impeded by continuous acetate supply. </LI> <LI> To enrich superior PHA producers a true feast is essential, a true famine is not. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>