EFFECT OF TEMPERATURE AND LIGHT ON THE BIOCHEMICAL PROFILE AND ANTIMICROBIAL ACTIVITY OF Chroococcus sp. R-10 (CYANOPROCARYOTA)

摘要

? 2021, Scibulcom Ltd.. All rights reserved.A newly isolated Bulgarian cyanoprokaryote Chroococcus sp. R-10 was studied to determine the appropriate cultivation conditions and the effect of light and temperature on the biomass composition. The strain was successfully grown in the temperature range 26–35oC, proving to be tolerant to higher light intensity. Under optimal conditions (26°C and unilateral illumination of 132 μmol photons m–2 s–1), the maximum yield obtained from Chroococcus sp. R-10 was 10.3 g L-1, after 336 hours of cultivation. The biomass contained 37% DW protein and higher amount of carbohydrates – 42% DW. The low temperature and lower light intensity favoured the biosynthesis of phycobiliproteins – 10.8% DW, while high light intensity stimulated the lipid accumulation in the cells – 16.4% DW. When studying the antimicrobial activity of some algal extracts, it was found that exopolysaccharide fraction and culture medium expressed significant antimicrobial activity against several Gr (–) and Gr (+) bacteria, as well as Candida albicans. Both microalgal samples were particularly effective towards Bacillus subtilis, but they had varying efficiency towards the other test-microorganisms. The ethanol extract showed only fungistatic action against Candida albicans. In general, Chroococcus sp. R-10 may be considered as one of the best biomass producers among the cyanoprokaryotes. The strain grows rapidly, accumulates large amounts of protein and exopolysaccharide, and produces antimicrobial substances, which gives it an advantage in potential future research and biotechnological application.