## 1 Introduction
Under large scale cultivation conditions, it accumulates 2-3% of DM of astaxanthin [1; 36; 37]. There are some other microalgae considered as potential carotenoid producers, except these two 'canonical' species. Particularly, there are pilot studies on assessment of biotechnological potential and carotenoid composition of _Coelastrella_ (formerly _Scotiellopsis_) _rubescens_ (Sphaeropleales) [39]. The microalgae accumulates predominantly astaxanthin and intermediates of its synthesis as well as \(\alpha/\beta\)-carotene under autotrophic growth conditions [40]. In the presence of CH\({}_{3}\)COONa a high fraction of canthaxanthin and pigments of violaxanthin cycle (violaxanthin and zeaxanthin) are observed in the biomass of _C. rubscens_[40]. _Chromochloris zofingeniensis_ (formerly _Chlorella zofingeniensis_) (Sphaeropleales) is one of the most extensively studied carotenogenic microalgae. It accumulates carotenoids, and, like other carotenogenic microalgae, triacylglyceredyn, under different stress factors, e.g., nitrogen starvation [22; 41; 42]. _Ch. zofingeniensis_ accumulates high amounts of lutein at early stages of cultivation, and later three predominant ketocarotonoids--astaxanthin, canthaxanthin and adonixanthin [22; 43; 44]. Its maximal astaxanthin content is 0.6% of cell DM [42], which is lower than in _H. lacustriis_. Astaxanthin (and other ketocarotonoid) yield can be increased under mixotrophic conditions: addition of glucose led to an increase of astaxanthin, canthaxanthin and adonixanthin [45]. However, addition of CH\({}_{3}\)COONa has not resulted in the increase of carotenoid production [44]. There are some microalgae considered as lutein (another widely used carotenoid) producers [46; 47; 48]. For example, _Muriellopsis_ sp. accumulates 150 mg\(\cdot\)m\({}^{-2}\cdot\)day\({}^{-1}\) of the pigment, which is comparable to production of astaxanthin and \(\beta\)-carotene in _Haematococcus_ and _Dunaliella_, respectively [46]. Its specific growth rate has been estimated as high as 0.17 day\({}^{-1}\)[46]. The strain _Scenedesmus_ sp. CCALA 1074 isolated from the plankton of the Sihl river (Switzerland) [49] accumulates lutein and mixture of ketocarotonoids. The cyanobacteria _Arthrospira_ spp. (formerly _Spirulina_ spp.) are also considered as a source of carotenoids. _A. platensis_ accumulates up to 15% of carotenoids. Its major carotenoids are \(\beta\)-carotene and zeaxanthin [50]. Isolation and characterization of new microalgae with a putative biotechnological potential is a topical issue. New species of the _Haematococcus_ genus, _H. rubicundus_ and _H. rubens_ were characterized in Central Europe [51; 52]. _H. rubicundus_ also was isolated in the White Sea coastal rock ponds [53]. A new species, _H. alpinus_, was found in New Zealand [54]. [PERSON] et al. [55] described a new genus _Sanguina_ (Chlamydomonasales, Chlamydomonasdomonadaceae) accumulating carotenoids. Carotenogenic microalgae often occupy ecological niches characterized by adverse conditions, e.g., melting snow or temporal rock ponds, due to their high stress tolerance, [32; 33; 56]. Strains of carotenogenic microalgae from the genera _Haematococcus_, _Coelastrella_ and _Bracteacoccus_ were isolated previously in the White Sea coastal zone [53; 57]. The goal of current work is to describe carotenoid composition and productivity of the new strain of the freshwater green microalga _B. agreggatus_ BM5/15 (IPPAS C-2045) from the White Sea region [53] cultivated autotropically in bubble-column photobioreactors.