XVI International Botanical Congess

Due to their morphological simplicity, the taxonomy of Chlorella typically involves laborious work. To address this problem, comparative biochemical and physiological studies have been carried out. Here, I present data on the chemical composition of cell walls of Chlorella, and discuss the taxonomic utility of this information. Sugar composition of the cell wall matrix is different across species, and can function as a fingerprint. The rigid portion of the cell wall consists of glucose and mannose, or of glucosamine. In microalgae other than Chlorella this composition differs. Cell walls of certain Chlorella are stained by ruthenium red, and some walls show anisotropy as an expression of crystallinity. Using sugar composition and other taxonomic markers, species of Chlorella can be classified. This classification is in accordance with the phylogenetic relationship inferred from sequence analysis, and will be compared with species-specific variation in pyrenoid structure and cell wall lytic activity.