Fluxes in PHA-storing microbial communities during enrichment and biopolymer accumulation processes

• Fluxes in microbial community composition in an enrichment reactor were analysed.
• The population was dominated by Flavisolibacter and Zoogloea; proportions varied.
• The effect of the underlying flux on polyhydroxyalkanoate accumulation was examined.
• PHA content and accumulation parameters remained relatively stable, composition was predictable.
• Mixed culture bacterial processes are functionally robust for PHA accumulation.

The use of mixed microbial cultures for the production of polyhydroxyalkanoates (PHAs) is emerging as a viable technology. In this study, 16S rRNA gene amplicon pyrosequencing was used to analyse fluctuations in populations over a 63-day period within a PHA-storing mixed microbial community enriched on fermented whey permeate. This community was dominated by the genera Flavisolibacter and Zoogloea as well as an unidentified organism belonging to the phylum Bacteroidetes. The population was observed to cycle through an increase in Zoogloea followed by a return to a community composition similar to the initial one (highly enriched in Flavisolibacter). It was found that the PHA accumulation capacity of the community was robust to population flux during enrichment and even PHA accumulation, with final polymer composition dependent on the overall proportion of acetic to propionic acids in the feed. This community adaptation suggests that mixed culture PHA production is a robust process.