TY - JOUR
T1 - Combining the enrichment and accumulation step in non-axenic PHA production: Cultivation of Plasticicumulans acidivorans at high volume exchange ratios
AU - Marang, Leonie
AU - van Loosdrecht, Mark C M
AU - Kleerebezem, Robbert
N1 - Accepted Author Manuscript
PY - 2016
Y1 - 2016
N2 - 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.
AB - 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.
KW - Cycle length
KW - Microbial enrichment culture
KW - Plasticicumulans acidivorans
KW - Polyhydroxybutyrate (PHB)
KW - Sequencing batch reactor (SBR)
KW - Volume exchange ratio
UR - http://resolver.tudelft.nl/uuid:b7ea5c36-c599-4023-a464-e67bb6a1e230
UR - http://www.scopus.com/inward/record.url?scp=84976381983&partnerID=8YFLogxK
U2 - 10.1016/j.jbiotec.2016.06.016
DO - 10.1016/j.jbiotec.2016.06.016
M3 - Article
AN - SCOPUS:84976381983
SN - 0168-1656
VL - 231
SP - 260
EP - 267
JO - Journal of Biotechnology
JF - Journal of Biotechnology
ER -