Effective cultivation conditions and safety evaluation of filamentous cyanobacteria producing phycocyanins with antiglycation activities.

We investigated suitable culture conditions for the production of the blue pigment phycocyanin (PC) from the unique filamentous cyanobacteria Pseudanabaena sp. ABRG5-3 and Limnothrix sp. SK1-2-1. White, green, or red LED irradiation at 30 µmol photons/m2/s was effective for phycocyanin production when compared with Arthrospira platensis (Spirulina) sp. NIES-39, which is generally grown under high light irradiation. To investigate the safety of the cyanobacteria, ABRG5-3 cells were subjected to Ames (reverse mutation) tests and single oral-dose rat studies, which revealed non-mutagenic and non-toxic properties. When three purified phycocyanins (abPC, skPC, and spPC) were subjected to agarose gel electrophoresis, they showed different mobility, indicating that each phycocyanin has unique properties. abPC exhibited strong antiglycation activities as novel function.

Development of a method for phycocyanin recovery from filamentous cyanobacteria and evaluation of its stability and antioxidant capacity.

BACKGROUND: Most commercial phycocyanins are extracted from a filamentous cyanobacterium, Arthrospira (Spirulina) platensis. Owing to the expenses of culture and complexities of the physical and chemical methods of phycocyanin purification, a more effective and simple method is required. RESULTS: We developed a new method for efficiently recovering the blue pigment protein, phycocyanin, from unique filamentous cyanobacteria, Pseudanabaena sp. ABRG5-3 and Limnothrix sp. SK1-2-1. The cells were cultivated in economy medium BG11 and lysed by adding water in a 1:16 ratio of wet cells to water. After extraction and purification, 28-30% dry cell weight of phycocyanin was obtained and its purity was confirmed. The stabilities of the phycocyanins at different pH in the presence of high temperature and light conditions and their antioxidant abilities were assessed. Results indicated that the phycocyanins were stable and possessed antioxidant properties. Interestingly, the Pseudanabaena phycocyanin was less likely to deteriorate under acidic conditions. CONCLUSIONS: Overall, we developed a promising and novel method for producing high functional phycocyanin concentrations at a low cost. The possibilities of adapting this new phycocyanin biorefinery to unique bioreactor utilization have also been discussed.

Biofuel production utilizing a dual-phase cultivation system with filamentous cyanobacteria.

Biomass yields and biofuel production were examined in a dual (solid and liquid)-phase cultivation system (DuPHA) with the unique filamentous cyanobacteria, Pseudanabaena sp. ABRG 5-3 and Limnothrix sp. SK1-2-1. Continuous circular cultivation was driven under the indoor closed (IC) or indoor opened (IO) conditions and provided biomass yields of approximately 8-27 g dry cell weight (DCW) floor m-2 d-1. Alkanes of heptadecane (C17H36) or pentadecane (C15H32) as liquid biofuels were also recovered from the lower liquid-phase, in which cyanobacteria were dropped from the upper solid-phase and continuously cultivated with a small amount of medium. After the main cultivation in DuPHA, the upper solid-phase of a cotton cloth on which cyanobacteria grew was dried and directly subjected to a combustion test. This resulted in the thermal power (kJ s-1) of the cloth with microalgae increasing approximately 20-50% higher than that of the cloth only, suggesting a possibility of using the solid phase with microalgae as solid biofuel.