Growth Kinetics of Nanofrustulum Shiloi Under Different Mixing Conditions in Flat-plate Photobioreactor

Abstract Diatoms are the major group of microalgae which have been utilized by the potential applications as food industries, aquatic feeds, cosmetics, biofuels, and pharmaceuticals. In this study, current approaches were made in order to determine growth rate, biomass productivity, protein, carbohydrate, lipid and fatty acid composition for Nanofrustulum shiloi cultures using both aeration and mixing conditions in flat-plate photobioreactor (PBR). Physical (the intensity of aeration, mixing, light intensity etc.) and chemical (nutritional materials) factors are affecting the growth and bioproduct contents of a diatom. Biomass and lipid productivities of N. shiloi were measured as 31.29 and 36.9622±0.0598 mg L-1 day-1 in flat-plate PBR having the combination of aeration and stirring system, respectively. A slightly higher amount of saturated fatty acids was detected in PBR having only bubbling system while the increase of mono- and poly- unsaturated fatty acids were found in PBR having the combination of aeration and stirring system. Flat-plate PBR design was also investigated for improving not only biomass but also the lipid productivity of N. shiloi.

Purification of phycocyanin from isolated and identified hot spring cyanobacteria

Phycocyanin is a phycobiliprotein used as a healthy food additive as well as an ingredient in cosmetic dye preparation. In this study, we attempted molecular and morphological identification of three thermophilic filamentous cyanobacteria and also explored a method to separate and purify thermostable C-phycocyanin of analytical grade from them for biotechnological applications. Cyanobacteria strains were collected from hot springs in Karakoc-Seferihisar, Gulbahce-Urla and Sifne-Cesme in Izmir, Turkey. The samples were identified both by morphological observations and genetic assay. Filamentous cyanobacteria DNA from the collected samples was isolated and extracted, and were analyzed using a 16S rRNA cyanobacteria-specific PCR and a denaturing-gradient gel electrophoresis (DGGE). Extraction and purification of phycocyanin was performed in two stages, ammonium sulfate saturation and dialysis, gel filtration and ion exchange chromatography. Conventional separation of Geitlerinema sp., Halospirulina sp. and Phormidium animale was successfully performed yielding C-phycocyanin at 493.760±3.610, 89.060±3.209, 32.978±0.350, 4.046±0.193, 8.303±0.511 and 4.196±0.090 mg/g purity from gel filtration and ion exchange chromatography processes, respectively. The SDS-PAGE demonstrated that the P. animale, Halospirulina sp. and Geitlerinema sp. were purified phycocyanin. Overall, in this study, three cyanobacteria were isolated and cultivated in a laboratory conditions, and then the cyanobacterial cells was extracted and purified thermostable C-phycocyanin obtained, which may be used as raw material in food supplement and pharmaceutical industry.