Two-stage (photoautotrophy and heterotrophy) cultivation enables efficient production of bioplastic poly-3-hydroxybutyrate in auto-sedimenting cyanobacterium

Abstract

Sustainable production of bioplastics by heterotrophic microbes has been restricted by the limited resources of organic substrates and the energy required for biomass harvest. Here, the easy-to-harvest cyanobacterium (Chlorogloea fritschii TISTR 8527), from which the biomass instantaneously settled to the bottom of liquid culture, was utilized to produce poly-3-hydroxybutyrate (PHB) using a two-stage cultivation strategy. The cells were first pre-grown under normal photoautotrophy to increase their biomass and then recultivated under a heterotrophic condition with a single organic substrate to produce the product. Through optimization of this two-stage cultivation, the mass conversion efficiency of acetate substrate to PHB was obtained at 51 ± 7% (w/w), the comparable level to the theoretical biochemical conversion efficiency of acetate to PHB. This two-stage cultivation that efficiently converted the substrate to the product, concurrent with a reduced culture biomass, may be applicable for the production of other biopolymers by cyanobacteria.

Utilization of shrimp wastewater for poly-β-hydroxybutyrate production by Synechocystis sp. PCC 6803 strain ΔSphU cultivated in photobioreactor

“…The photosynthesis efficiency was analyzed in terms of O 2 -evolving ability of cells (10 μg chl a mL −1 ) under saturating white light (500 μE m -2 s −1 ) with a Clark-type O 2 -electrode (Hansatech instruments, UK) at 25 ○ C as described by [ 12 ]. The PHB synthase activity was determined as previously described by [ 13 ]. The reaction (1 mL) contained 0.2 mg of crude protein, 1.5 mM of β-hydroxybutyryl-CoA substrate and 0.5 mM of 2-nitrobenzoic acid in 25 mM Tris-HCl buffer pH 7.5 containing 5% (v/v) glycerol.…”

Development and Characterization of Biocompatible Polyhydroxy Butyrate Impregnated With Herbal Plants Against Wound Healing Activity on in Vivo Animal Model

“…The TS, elongation break %, and Young's modulus were examined. The evaluation of PHB and PHB/PP blendes degradation was carried out by Pachekoski et al [17] showed that the TS of PHB and PHB/PP blends was 28.5 and 24.5 Mpa with elongation break 2.5 and 1.5 with higher Young's modulus of 2045 and 1885 Mpa, respectively, degraded after 90 days in soil and reported with decrease in TS with which increases the degrading rate, the TS of PHB produced by cyanobacterium Chlorogloea fritschii was 23Mpa with elongation break 5.5 and Young's modulus was 712Mpa [18]. The PHB produced in our study was entirely thin with F7 producing 0.39 Mpa TS and 25.7 elongation break and 325 Mpa Young's modulus which indicates that the PHB with lesser TS can act as a good biodegradable material.…”

Disruption of cyanobacterial γ-aminobutyric acid shunt pathway reduces metabolites levels in tricarboxylic acid cycle, but enhances pyruvate and poly(3-hydroxybutyrate) accumulation

“…Physical properties were examined using a material analyzing machine (Hounsfield H10KM, UK). Thermal properties and polymer molecular weight was determined as described 23 .…”