Influence of feedstock source on the development of polyhydroxyalkanoates-producing mixed microbial cultures in continuously stirred tank reactors

Polyhydroxyalkanoates (PHAs) are the new frontier of bioplastic production; however, research is needed to develop and characterise efficient mixed microbial communities (MMCs) for their application with a multi-feedstock approach. Here, the performance and composition of six MMCs developed from the same inoculum on different feedstocks were investigated through Illumina sequencing to understand community development and identify possible redundancies in terms of genera and PHA metabolism. High PHA production efficiencies (>80% mg COD_PHA mg^-1 COD_OA-consumed) were seen across all samples, but differences in the organic acids (OAs) composition led to different ratios of the monomers poly(3-hydroxybutyrate) (3HB) to poly(3-hydroxyvalerate) (3HV). Communities differed across all feedstocks, with enrichments in specific PHA-producing genera, but analysis of potential enzymatic activity identified a certain degree of functional redundancy, possibly leading to the general high efficiency seen in PHA production from all feedstocks. Leading PHAs producers across all feedstocks were identified in genera such as Thauera, Leadbetterella, Neomegalonema and Amaricoccus.