Identification and comprehensive characterization of a new soil strain of carotenogenic microalgae Chlorosarcinopsis sp. VKM Al-296 (Chlorophyta)

Abstract

We conducted a complex study of the new green microalgae strain VKM Al-296, isolated from arable soil and identified as Chlorosarcinopsis sp. (Chlamydomonadales, Chlorophyta), using molecular phylogenetic analysis (18S rDNA and ITS2 sequences) and light and scanning electron microscopy. The strain’s morphology, growth, and carotenogenesis during two-stage batch cultivation were studied. In a liquid medium, the cells occurred singly or in packages surrounded by extracellular mucilage, with cell sizes of 3-6 µm. By the end of the “green” stage (vegetative growth) lutein was the predominant pigment, accounting for >60% of the total carotenoids. Other primary carotenoids were also present: beta-carotene (14.6%), neoxanthin (11.1%), and antheraxanthin (7.1%). At the end of the “red” (secondary carotenogenesis) stage, the culture’s dry biomass content was 1.92±0.04 g/L, with carotenoids accounting for 0.3% of the dry biomass. The pigment profile was dominated by ketocarotenoids: astaxanthin (mono- and diesters), canthaxanthin, and adonixanthin monoesters (35%, 21% and 20% of the total carotenoid content, respectively). Over the entire cultivation period (17 days), the average biomass productivity and total carotenoid productivity were 0.10 g/L/day and 0.2 mg/L/day, respectively. Chlorosarcinopsis sp. VKM Al-296 may be a perspective object of further research aimed at optimizing cultivation conditions as a source of lutein at the “green” stage, as well as canthaxanthin and esters of astaxanthin and adonixanthin at the “red” stage.