Seasonal variation of carrageenans from Chondracanthus chamissoi with a review of variation in the carrageenan contents produced by Gigartinales

Abstract

Seasonal and geographic variations in carrageenan biosynthesis influence the commercial value and industrial applications of these phycocolloids due to the variation in yield and quality. This study examined the effects of season and seaweed origin on the carrageenans produced by the isomorphic phases of the red alga Chondracanthus chamissoi collected during winter and summer from two localities in the SE Pacific Ocean (northern-central Chile). Results were compared with those from other carrageenan-producing seaweeds, and a random forest analysis was carried out with the carrageenan contents reported for Gigartinales in order to determine the principal variables influencing carrageenan yields. The mean carrageenan contents of C. chamissoi ranged from 15.2 to 42.1% DW. Higher yields were observed in gametophytes than in tetrasporophytes, and in samples collected in summer than in winter. Seaweeds from the site close to a local upwelling center had more carrageenans than those from a more distant site. The chemical composition of the carrageenans of C. chamissoi varied only between phases. Carrageenan contents reported for Gigartinales vary from 5.4 to 75.5% DW. The random forest model showed a large accuracy explaining variation in carrageenan yields (pseudo-r2 = 0.63), where genus was ranked as the most important factor, followed by biogeographical origin, solar radiation, nitrate concentrations, and temperature. Considering that the understanding of the genetic basis of carrageenan biosynthesis is limited, our analysis highlights the need for experimental studies examining the effects of taxon and geographical origin in these polysaccharides as a strategy for improving both carrageenan quality and quantity through strain selection.