Combining the enrichment and accumulation step in non-axenic PHA production: Cultivation of Plasticicumulans acidivorans at high volume exchange ratios

Marang, L.; van Loosdrecht, Mark C.M.; Kleerebezem, R.

doi:10.1016/j.jbiotec.2016.06.016

Combining the enrichment and accumulation step in non-axenic PHA production: Cultivation of Plasticicumulans acidivorans at high volume exchange ratios

Title

Combining the enrichment and accumulation step in non-axenic PHA production: Cultivation of Plasticicumulans acidivorans at high volume exchange ratios

Author

Marang, L. (TU Delft BT/Environmental Biotechnology)
van Loosdrecht, Mark C.M. (TU Delft BT/Environmental Biotechnology)
Kleerebezem, R. (TU Delft BT/Environmental Biotechnology)

Date

2016

Abstract

The process for non-axenic polyhydroxyalkanoate (PHA) production from organic waste generally comprises three steps: acidogenic fermentation of the waste stream, enrichment of a PHA-producing culture, and production of the PHA. This study assesses the feasibility of combining the enrichment and production step. Harvesting PHA-rich biomass directly from the sequencing batch reactor (SBR) used for enrichment of the microbial culture reduces capital cost, but may increase downstream-processing cost if the PHA content is significantly lowered. Operating an acetate-fed SBR at a volume exchange ratio of 0.75 (18 h cycles, 1 d SRT) allowed the production of biomass with 70 wt% poly(3-hydroxybutyrate) (PHB) in a single-step process. By increasing the exchange ratio to 0.83 (20 h cycles) the PHB content of the harvested biomass increased to 75 wt%, but the operational stability decreased. SBR operation at these high exchange ratios makes that bacteria have to increase their growth rate and external substrate is available for relatively long periods. This allows the establishment of larger flanking populations and negatively affected the kinetic properties of Plasticicumulans acidivorans, the predominant organism. Maximizing the volume exchange ratio is, therefore, a suitable strategy to produce large amounts of PHA in the SBR, but does not ensure the enrichment of a culture with superior PHA productivity.

Subject

Cycle length
Microbial enrichment culture
Plasticicumulans acidivorans
Polyhydroxybutyrate (PHB)
Sequencing batch reactor (SBR)
Volume exchange ratio

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http://resolver.tudelft.nl/uuid:b7ea5c36-c599-4023-a464-e67bb6a1e230

DOI

https://doi.org/10.1016/j.jbiotec.2016.06.016

Embargo date

2017-06-27

ISSN

0168-1656

Source

Journal of Biotechnology (online), 231, 260-267