Abstract
The differentiation between wild type of Parachlorella kessleri and its mutant strains PC Mut2 , PC Mut4 by using the Multi-functional Plant Efficiency Analyzer (М-РЕА-2) was studied. Mutant algal cells of P. kessleri have been obtained by UV-C during 3 and 10 min respectively. Light-induced kinetics of prompt fluorescence (OJIP transients), delayed fluorescence and modulated reflection at 820 nm (redox transitions of P 700 in PSI) showed disturbance of electron transport flow in photosystem II (PSII) and an increase fraction of non-reducing centers of secondary quinone acceptors of electron (Q B ). In addition, the amplitudes of the fast and slow peak in the kinetics of the delayed light emission and non-photochemical fluorescence quenching ( NPQ) were significantly reduced in mutant cells, indicating low level of the membrane energization of photosynthetic membranes. Changes of photosynthetic reactions of mutants may lead to an increase of the carotenoids content, which protect cells against the light stress. It is suggested to use parameters of induction curves of prompt and delayed fluorescence to characterize mutant algal cells in biotechnological studies.