Development of a spectrophotometric method for quantification of C-phycocyanin in the cyanobacterium Aphanizomenon flos-aquae

This study presents the development of a reliable method for quantifying C-phycocyanin. It was found that the spectrophotometric method commonly used for C-phycocyanin quantification tends to overestimate the actual amount of C-phycocyanin in Aphanizomenon flos-aquae (AFA) samples. The aim of this study was therefore to adapt the spectrophotometric C-phycocyanin quantification method specifically for A. flos-aquae, accounting for the variation in C-phycocyanin between different cyanobacteria species. High performance liquid chromatography (HPLC) was used as reference method and to avoid interference between molecules. The existing spectrophotometric equations for quantifying AFA C-phycocyanin were adapted using a C-phycocyanin standard. The method was then used to obtain a new set of spectrophotometric quantification equations adapted to the strain of interest and ensuring the accuracy of C-phycocyanin quantification while continuing to use a rapid, simple, and inexpensive method of pigment quantification. The method developed here could also be adapted to improve quantification methods for other types of phycocyanin, cyanobacteria, and other compounds of interest that are currently quantified by spectrophotometry.

Automated summary

This study developed a reliable method to quantify C-phycocyanin, specifically for Aphanizomenon flos-aquae (AFA) samples. The commonly used spectrophotometric method tends to overestimate the amount of C-phycocyanin, so the aim was to adapt the method for AFA and account for variation in C-phycocyanin between different cyanobacteria species. High performance liquid chromatography (HPLC) was used as a reference method, and a new set of spectrophotometric quantification equations was obtained. This method has the potential to improve quantification methods for other types of phycocyanin, cyanobacteria, and compounds currently quantified by spectrophotometry.