Impact of Famine Length on the Structure and Performance of a PHA-Accumulating Community Under Uncoupled Feeding

Polyhydroxyalkanoates (PHAs) are a group of polymers that are naturally synthesized by various microorganisms and have proven to be potential alternatives to conventional plastics due to their biodegradability and versatile composition. Current industrial PHA production relies on specific bacterial strains, and therefore requires highly purified substrates and sterile environments resulting in high production costs. To improve economic viability, several strategies are being explored, including the use of mixed microbial communities (MMCs). The widely accepted method of Aerobic Dynamic Feeding (ADF) involves the ecological selection of PHA-accumulating MMCs by shifting between excess (feast) and limited (famine) availability of external substrates. To improve PHA productivity, a parallel approach, the uncoupled feeding, has been introduced within the traditional feast and famine regime, but has not yet been fully explored. This study highlights the influence of different famine periods on the selection of PHA-accumulating MMCs under uncoupled feeding by monitoring PHA accumulation during the selection step and relating to microbial community evolution. Results indicated that, lengthening the famine phase, PHA accumulation improved its performance in terms of PHA content in the biomass at the end of the feast (from 14 to 24%). However, the microbial community dynamics did not show consistent changes in the dominant PHA-accumulating bacteria (namely Paracoccus and Thaurea).This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 872053.