Polyhydroxybutyrate (PHB) is a biodegradable biopolymer, accumulated in the bacterial cells as energy storage under nutrient-limited condition.  PHB shares similar physical and chemical characteristics to conventional petroleum-based plastics; therefore, much attention has been directed towards its sustainable and economical production.  This study investigated the feasibility of producing PHB by salt-tolerant bacterial strains grown with cheap renewable resources such as crude glycerol, high-strength saline wastewater, and municipal activated sludge under non-sterile salty conditions.  Our results showed that <i>Zobellella denitrificans </i>ZD1 (referred as ZD1 hereafter) accumulated the highest PHB (84% of its dry cell weight (DCW)) at a short cultivation period of 24 hrs and this strain could tolerate salt content as high as 5% NaCl in glycerol.  Additionally, under high salinity, ZD1 withstood 1% fatty acids, which are present as impurities in crude glycerol, a byproduct from biodiesel production.  The ability of ZD1 to overcome, prosper, and produce higher PHB contents under high salt conditions has shown to link to its ability to synthesize ectoine as an osmolyte.  Multiple factors including pH, carbon/nitrogen ratio, nitrogen sources, electron acceptors, and salinity were further examined to optimize PHB production by ZD1.  Overall, our results suggested the application of strain ZD1 to salty wastewater for non-sterile PHB production, which can significantly reduce the PHB production cost associated with energy-intensive sterilization and expensive organic feedstock.

Sustainable production of polyhydroxybutyrate (PHB) by <i>Zobellella denitrificans </i>ZD1 grown with non-sterile salty waste streams

2019 Fall National Meeting

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Sustainable production of polyhydroxybutyrate (PHB) by Zobellella denitrificans ZD1 grown with non-sterile salty waste streams