Polyhydroxyalkanoates (PHA) production by mixed microbial cultures
(MMC) became the central point of many research works. Firstly discovered in
wastewater treatment systems, namely those related with biological phosphorus
removal, it became a process to be considered for polymer production intended to
replace petrochemical derived plastics. The ability to store PHA provides microbial
communities a competitive advantage for survival under transient conditions typical of
waste treatment systems. In this way, MMC can continuously adapt to the operational
conditions increasing the number PHA-storing organisms with minimum requirements
of sterility. MMC can produce PHA using waste or industrial by-products as substrates,
allowing for their valorization. The use of waste, together with the lower requirements
in sterility and process control, could signify a decrease on PHA production costs. The
price is one of the main drawbacks that prevent the increase of world PHA market
share. This chapter intends to contextualize the use of MMC for PHA production, by
describing the different approaches and compare them with the traditional processes
employing pure or genetically modified organisms. The main processes to select PHAstoring
MMC are discussed, namely alternating of anaerobic and aerobic (AN/AE) or anoxic (AN/AO) conditions and aerobic dynamic feeding (ADF). The use of wastes as
substrates, the operational conditions, the microorganisms involved as well as the
molecular methods used for their identification are also the focus of this work.
Keywords: ADF, AN/AE, Mixed microbial cultures, Molecular methods, Operational conditions, Polyhydroxyalkanoates, Selection, Valorization, Waste, Waste treatment.
