Pisum sativum (L.) plants were grown under "white" luminescent lamps, W [45 µmol(quantum) m -2 s -1 ] or under the same irradiation supplemented with narrow spectrum red light-emitting diodes (LEDs), RE [λ max = 660 nm, ∆λ = 20 nm, 40 µmol(quantum) m -2 s -1 ]. Significant differences in the chlorophyll (Chl) a fluorescence parameters, degree of State 1-State 2 transition, and the pigment-protein contents were found in plants grown under differing spectral composition. Addition of red LEDs to the "white light" resulted in higher effective quantum yield of photosystem 2 (PS2), i.e. F' v /F' m , linear electron transport (φ PS2 ), photochemical quenching (q P ), and lower non-photochemical quenching (q N as well as NPQ). The RE plants were characterised by higher degree State 1-State 2 transition, i.e. they were more effective in radiant energy utilisation. Judging from the data of "green" electrophoresis of Chl containing pigment-protein complexes of plants grown under various irradiation qualities, the percentage of Chl in photosystem 2 (PS2) reaction centre complexes in RE plants was higher and there was no difference in the total Chl bound with Chl-proteins of light-harvesting complexes (LHC2). Because the ratio between oligomeric and monomeric LHC2 forms was higher in RE plants, we suggest higher LHC2 stability in these ones.

Nanoaquachelates, the nanoparticles with the molecules of water and/or carboxylic acids as ligands, are used in many fields of biotechnology. Ultra-pure nanocarboxylates of microelements are the materials of spatial perspective. In the present work, the effects of copper and selenium nanoaquachelates carboxylated with citric acid on biomass accumulation of the green algae Chlorella vulgaris were examined. Besides, the efficiency of the reactions of the light stage of photosynthesis was estimated by measuring chlorophyll a fluorescence. The addition of 0.67–4 mg L−1 of Cu nanocarboxylates resulted in the increase in Chlorella biomass by ca. 20%; however, their concentrations ranging from 20 to 40 mg L−1 strongly inhibited algal growth after the 12th day of cultivation. Se nanocarboxylates at 0.4–4 mg L−1 concentrations also stimulated the growth of C. vulgaris, and the increase in biomass came up to 40–45%. The addition of Se nanocarboxylates at smaller concentrations (0.07 or 0.2 mg L−1) at first caused the retardation of culture growth, but that effect disappeared after 18–24 days of cultivation. The addition of 2–4 mg L−1 of Cu nanocarboxylates or 0.4–4 mg L−1 of Se nanocarboxylates caused the evident initial increase in such chlorophyll a fluorescence parameters as maximal quantum yield of photosystem II photochemistry (F v/F m) and the quantum yield of photosystem II photochemistry in the light-adapted state (F v'/F m'). Photochemical fluorescence quenching coefficients declined after 24 days of growth with Cu nanocarboxylates, but they increased after 6 days of the addition of 2 or 4 mg L−1 Se nanocarboxylates. Those alterations affected the overall quantum yield of the photosynthetic electron transport in photosystem II.

Methanol in low concentrations can stimulate the mixotrophic growth of some microscopic algae. The aim of the present work was to investigate the effect of methanol on the growth, photosynthesis, and respiration rate as well as free amino acid and soluble protein content in the cells of unicellular green alga Chlamydomonas reinhardtii. It was shown that 30-100 mM methanol induced an increase in C. reinhardtii biomass production compared to controls without the solvent. The packed cell volume was increased maximally by 35 % after growing for 6 days in the presence of 50 mM methanol. The effect was light-dependent, although the rate of photosynthesis changed insignificantly while the rate of respiration increased. The intracellular content of reduced nicotinamide coenzyme NAD(P)H also increased after methanol addition in the light. The intracellular content of free amino acids increased by 31 % as a result of 50 mM methanol addition, and their composition changed: glutamic acid, glutamine, alanine, serine, and tyrosine increased and methionine content decreased. The content of soluble protein also increased by 30 %, eliminating the possibility of proteolysis. Thus, methanol has a positive effect on nitrogen assimilation as indicated by the increase in the content of soluble proteins and free amino acids. This effect may be connected with methanol-induced stimulation of respiration and the lightdependent increase in NAD(P)H content. The results suggest that methanol not only is a carbon source for C. reinhardtii cells but also can take part in energy metabolism.