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Carotenoids have received particular attention both for their importance in algal systematics and hydrobiology and for their health benefits for humans, along with other applications in various industries. Here, we provide new data on the carotenoid content of five Vischeria/ Eustigmatos strains isolated from aeroterrestrial habitats in Bulgaria and kept in the Algal Collection of Sofia University (ACUS). The obtained pigment pattern with nine carotenoids and generalization of literature data allowed us to update the knowledge on the chemotaxonomic characteristics of Eustigmatophyceae with a total of 47 pigments reported for the group, out of which 37 are carotenoids. The important photosynthetic pigment lutein, considered also a high-value product with extensive applications in feed, food, nutraceutical and pharmaceutical industries, was proved as a novel carotenoid for the group. The results also confirmed the presence of luteoxanthin, which is rarely reported in algae. All strains had a high content of the commercially valuable health-promoting xanthophyll astaxanthin. There were also different amounts of beta-carotene, violaxanthin, vaucheriaxanthin, canthaxanthin, zeaxanthin and antheraxanthin. Based on the differences in the pigment composition of the members of the ecological groups of aquatic and aeroterrestrial species, we propose the existence of two main pigment types in the class Eustigmatophyceae, with the aquatic type further divided into freshwater and marine pigment subtypes.

This review provides data on the possibilities for commercial use of algae of the green streptophyte genus Klebsormidium. It is one of the basal algal progenitors of land plants and shows many mechanisms and features which allow its adaptation to different environmental stresses associated with land colonization. This has led to formation of structures and compounds with countless possible applications in biotechnology and nanotechnology, starting from food to pharmaceuticals and biofuels. Therefore, the present work aims to provide: (1) a review on this yet neglected topic for the first time; (2) reliable identification using the polyphasic taxonomic approach of three local Klebsormidium strains isolated from soils of two protected areas in Bulgaria (Kresnendko Defile and National park Rila). It also outlines the cultivation advantages of Klebsormidium broad tolerance to harsh conditions and its reproductive features (easy disintegration and possibility to produce resting stages). The possibility to use inoculum of akinetes in soil algalization as biofertilizers is proposed. The results from standard microscopical identification and molecular data (ITS and rbcL, used separately and in combination), combined in the applied polyphasic approach led to distinguishing between geographically distinct strains collected at different altitudes. After identification of two strains (ACUS 00001 and ACUS 00014) as belonging to Klebsormidium dissectum and of ACUS 00207 as belonging to Klebsormidium klebsii, the similarity of the latter taxon with K. nitens is discussed. ARTICLE HISTORY