A Combination of Aqueous Extraction and Ultrafiltration for the Purification of Phycocyanin from Arthrospira maxima.

Dante Matteo Nisticò,Carmela Conidi,Rosanna Morelli,Alberto Figoli,Amalia Piro,Silvia Mazzuca,Francesco Antonio Fagà,Daniela Oliva,Alfredo Cassano,Vincenzo Osso

doi:10.3390/microorganisms10020308

Dante Matteo Nisticò, Carmela Conidi + Show 8 more

Open Access

https://doi.org/10.3390/microorganisms10020308

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Abstract

The purification of phycocyanin (PC) from Spirulina generally involves a combination of different techniques. Here, we report the results on PC yields from a combined aqueous extraction-ultrafiltration (UF) process of a strain of Arthrospira maxima cultivated in a farm devoted to producing PC with food-grade purity. Samples optimized from different biomass/solvent ratios were purified by using a polyethersulphone (PES) membrane with a molecular weight cut-off (MWCO) of 20 kDa. The UF system was operated at 2.0 ± 0.1 bar and at 24 ± 2 °C up to a volume concentration factor (VCF) of 5. A diafiltration (DF) process was conducted after UF in order to increase the PC recovery in the retentate. Samples were collected during both UF and DF processes in order to evaluate membrane productivity and PC purity. The average permeate fluxes of about 14.4 L/m2h were measured in the selected operating conditions and more than 96% of PC was rejected by the UF membrane independently ofthe extraction yields and times. The concentration of PC in the final retentate was 1.17 mg/mL; this confirmed the observed rejection and the final VCF of the process (about 5-fold when compared to the concentration of PC in the crude extract). In addition, the combination of UF and diafiltration allowed the removal of about 91.7% of the DNA from the crude extract, thereby improving the purity of the phycocyanin in the retentate fraction.

Highlights

Photosynthetic organisms, such as microalgae and cyanobacteriarepresent promising renewable sources of healthy food ingredients and functional food products due to their high contents of bioactive compounds, such as essential amino acids, antioxidant molecules, minerals and fibers
The biomass-solvent ratio of 0.02 g/mL makes possible the use of smaller volumes of extractant in the purification steps and it agrees with data reported by Silveira et al [29] in the optimization of PC extraction from Spirulina platensis using factorial design
The authors reported that the use of a biomass-solvent ratio higher than 0.08 g/mL produced very concentrated suspensions so that the solvent was unable to promote an appropriate interaction with the biomass for efficient extraction

Summary

Introduction

Photosynthetic organisms, such as microalgae and cyanobacteriarepresent promising renewable sources of healthy food ingredients and functional food products due to their high contents of bioactive compounds, such as essential amino acids, antioxidant molecules, minerals and fibers. Compared to other natural sources of bioactive ingredients, these organisms have many advantages, including a wide biodiversity, the possibility to grow under conditions of low water utilization and the plasticity of their metabolism, which can be induced to produce specific molecules [1,2]. Arthrospira platensis (traditionally known as Spirulina), a blue-green coil shaped species, has received increased attention in receent years due to its high content of proteins, vitamins, minerals and many essential amino-acids and fatty acids [4]. It is an important source of phycocyanin (PC) and allophycocyanin (APC). PC is a natural blue colorant, with an estimated molecular weight of 100–200 kDa; thanks to its therapeutic

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