Reliability of color measurements for monitoring pigment content in a biofilm-forming cyanobacterium

Pigment content provides valuable information about the growth and physiological status of organisms. This study investigated the relationship between pigment content (chlorophyll a, total carotenoids and phycobiliproteins) and reflectance color measurements, expressed by means of the CIELAB color coordinates. The experimental design was carried out with a biofilm-forming cyanobacterium of the genus Nostoc grown under different environmental conditions (nitrate and phosphate concentrations and light intensity). Analysis of the results revealed a close correlation between pigment content and CIELAB color coordinates and enabled formulation of predictive equations for estimating chlorophyll a and total carotenoid content. The interest in monitoring biofilm development on cultural heritage monuments has arisen within the field of preventive conservation and explains the importance of developing a simple non-destructive method of microorganism assessment based on color measurements, which can be performed rapidly on site and is cost-effective.

► Pigment production in cyanobacterial cultures varies with environmental conditions. ► Different pigment content is closely correlated to variations in color. ► Regression equations predicted chl a and total carotenoid contents from L* and Cab∗. ► Progress in the development of a colorimetric method for monitoring colonization.