Phycocyanin is a blue water-soluble pigment essential for photosynthesis in cyanobacteria, with high commercial value. Its production involves biomass extraction, concentration, and drying, but these processes are costly and need refinement. Concentration often includes partial purification via ammonium sulfate precipitation, though this method lacks standardization and relies on fixed recipes. This study aimed to develop a solubility curve for phycocyanin in ammonium sulfate to standardize and optimize the precipitation process, ensuring better control over pigment recovery and increasing efficiency. For this purpose, extracts obtained through enzymatic cell disruption were employed, yielding approximately 37.06 mg phycocyanin g-1 dry biomass, with a purity <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10811_2025_3548_Article_IEq1.gif" Format="GIF" Height="26" Rendition="HTML" Resolution="72" Type="Linedraw" Width="51" /> </InlineMediaObject> <EquationSource Format="TEX">$(\frac{{OD}_{620}}{{OD}_{280}})$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo stretchy="false">(</mo> <mfrac> <msub> <mrow> <mi mathvariant="italic">OD</mi> </mrow> <mn>620</mn> </msub> <msub> <mrow> <mi mathvariant="italic">OD</mi> </mrow> <mn>280</mn> </msub> </mfrac> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> of 1.20. By adding varying concentrations of ammonium sulfate to the crude phycocyanin extract, solubility curves were generated, leading to a Cohn-type equation for phycocyanin solubility as a function of ammonium sulfate concentration. Using this equation, it was possible to predict a theoretical recovery of around 95% of phycocyanin, with ammonium sulfate at a concentration of 204.48 g L-1 from crude extracts with a phycocyanin concentration of 15 mg mL-1. The actual recovery of the pigment was close to 80%, with a purity of approximately 2.9 following a two-stage precipitation. The phycocyanin solubility equation developed allows for precise estimation of ammonium sulfate concentration needed for precipitation, reducing costs from excessive precipitant use. However, variations in results may occur due to the complexity of the crude extract, containing a mixture of released proteins.

Development of a solubility equation for phycocyanin precipitation by ammonium sulfate

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发表日期：

2025年5月28日

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Juliana Corrêa Cardoso,
Denisse Tatiana Molina-Aulestia,
Hissashi Iwamoto,
Maria Clara Manzoki,
Carlos Ricardo Soccol,
Júlio Cesar de Carvalho

摘要

Phycocyanin is a blue water-soluble pigment essential for photosynthesis in cyanobacteria, with high commercial value. Its production involves biomass extraction, concentration, and drying, but these processes are costly and need refinement. Concentration often includes partial purification via ammonium sulfate precipitation, though this method lacks standardization and relies on fixed recipes. This study aimed to develop a solubility curve for phycocyanin in ammonium sulfate to standardize and optimize the precipitation process, ensuring better control over pigment recovery and increasing efficiency. For this purpose, extracts obtained through enzymatic cell disruption were employed, yielding approximately 37.06 mg phycocyanin g^-1 dry biomass, with a purity $(\frac{{OD}_{620}}{{OD}_{280}})$ $(\frac{{OD}_{620}}{{OD}_{280}})$ of 1.20. By adding varying concentrations of ammonium sulfate to the crude phycocyanin extract, solubility curves were generated, leading to a Cohn-type equation for phycocyanin solubility as a function of ammonium sulfate concentration. Using this equation, it was possible to predict a theoretical recovery of around 95% of phycocyanin, with ammonium sulfate at a concentration of 204.48 g L^-1 from crude extracts with a phycocyanin concentration of 15 mg mL^-1. The actual recovery of the pigment was close to 80%, with a purity of approximately 2.9 following a two-stage precipitation. The phycocyanin solubility equation developed allows for precise estimation of ammonium sulfate concentration needed for precipitation, reducing costs from excessive precipitant use. However, variations in results may occur due to the complexity of the crude extract, containing a mixture of released proteins.