Pilot-scale production of poly-β-hydroxybutyrate with the cyanobacterium Synechocytis sp. CCALA192 in a non-sterile tubular photobioreactor

Abstract

Poly-β-hydroxybutyrate (PHB) is considered as one of the most promising bioplastics. It has a broad range of applications and is degraded relatively rapidly by soil organisms. Like many prokaryotes, the cyanobacterium Synechocystis sp. CCALA192 produces this biopolymer as a storage compound, especially under nutrient starvation.In a 200-liter tubular photobioreactor, we cultivated Synechocystis sp. CCALA192 semi-continuously over a period of 75 days with CO 2 as sole carbon source. A two-stage cultivation strategy was performed, where after 5-7 days nitrogen was depleted and the culture started to produce PHB and gradually turned from blue-green to yellow. After 16-20 days, 90% of the culture was harvested and the residual 10% was used as inoculum for the following cycle. The harvested culture had an average biomass concentration of 1.0 g/L with an average PHB content of 12.5% of cell dry weight. After restarting with fresh nutrients, the yellow culture turned blue-green again and degraded the PHB within 24-48 hours. When nitrogen of the medium was consumed, PHB was produced again and the cycle continued. In the late stage of each production cycle, a ripening process was observed, where no CO 2 was consumed but the PHB concentration was still rising at the expense of the existing glycogen rich biomass.Establishing a stable Synechocystis sp. CCALA192 culture under non-sterile conditions turned out to be difficult, as this small unicellular organism is very sensitive and easily grazed by protozoa. Therefore, a special cultivation strategy with partially anoxic conditions was necessary.

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

“…PCC 6714 BG11 Jacketed glass photobioreactor (1 L), under nitrogen and phosphorus limitation for 15 days 16.4 ± 2.0 [ 25 ] Synechocystis sp. CCALA192 BG11 Tubular photobioreactor (200 L), under complete BG11 medium cultivation for 20 days 12.7 [ 26 ] Synechocystis sp. PCC 6803 strain ∆SphU BG11 Flat-plate photobioreactor (10 L), under complete BG11 medium cultivation for 13 days (control condition) 6.42 ± 1.8 This study Synechocystis sp.…”

Cyanobacteria for PHB Bioplastics Production: A Review

“…In 2018, Troschl et al could report 12.5% PHB cry well weight [21]. In the same year, Kamravamanesh et al have shown that the cyanobacterium Synechocystis sp.…”

“…It is known that cyanobacteria can produce PHB as an intracellular energy and carbon storage compound [21] (see Figure 1).…”

Bioprocess Engineering Aspects of Sustainable Polyhydroxyalkanoate Production in Cyanobacteria

“…The maximum PHB content of 125 mg L −1 was obtained for the non-sterile batch cultivation of Synechocystis sp. CCALA192 in a 200-L tubular photobioreactor [42]. Moreover, PHB was produced using optimized media in a one-liter tank reactor for the wild-type cyanobacterial strain Synechocystis sp.…”