초록
<P><B>Abstract</B></P><P>In this study we investigated the use of lactate and a lactate/acetate mixture for enrichment of poly‐3‐hydroxybutyrate (PHB) producing mixed cultures. The mixed cultures were enriched in sequencing batch reactors (SBR) that established a feast–famine regime. The SBRs were operated under conditions that were previously shown to enable enrichment of a superior PHB producing strain on acetate (i.e., 12 h cycle length, 1 day SRT and 30°C). Two new mixed cultures were eventually enriched from activated sludge. The mixed culture enriched on lactate was dominated by a novel gammaproteobacterium. This enrichment can accumulate over 90 wt% PHB within 6 h, which is currently the best result reported for a bacterial culture in terms of the final PHB content and the biomass specific PHB production rate. The second mixed culture enriched on a mixture of acetate and lactate can produce up to 84 wt% PHB in just over 8 h. The predominant bacterial species in this culture were <I>Plasticicumulans acidivorans</I> and <I>Thauera selenatis</I>, which have both been reported to accumulate large amounts of PHB. The data suggest that <I>P. acidivorans</I> is a specialist on acetate conversion, whereas <I>Thauera</I> sp. is a specialist on lactate conversion. The main conclusion of this work is that the use of different substrates has a direct impact on microbial composition, but has no significant effect on the functionality of PHB production process. Biotechnol. Bioeng. 2011;108:2022–2035. © 2011 Wiley Periodicals, Inc.</P>