Pigments content in Сhlorella vulgaris under the influence of the sodium selenite and the ions of metals

Abstract

We investigated the content of pigments in Chlorella vulgaris Beij. (Chlorophyta) under the influence of sodium selenite in concentrations based on Se4+ 0.5, 5.0, 10.0 and 20.0 mg/dm3 during one, three and seven days and under the influence of the simultaneous action of selenite in concentrations 10 mg Se4+/dm3 and ions of Zn2+, Mn2+, Co2+,Cu2+, Fe3+ in concentrations 5.00, 0.25, 0.05, 0.008 and 0.002 mg/dm3over seven days. This research was carried out to establish the conditions for obtaining algal lipidis substance enriched with selenium and biogenic metals in the aquaculture. The content of pigments was determined spectrophotometrically, the cellular walls were separatedby centrifuge in the percoll gradient and investigated microscopically. The pigments content in the Ch. vulgaris increased by 1.5–2.5 times in comparison with the control sample under the influence of 10 mg Se4+/dm3 with and without metal ions, in all variants of experimental influence due to binding of SeО32– with proteins and lipids. We found that selenium was included in all lipid fractions (triacylglycerols, dyacylglycerols, phospholipids, nonetherified fatty acids); the maximum amount of selenium-containing lipids wasrecorded in chloroplasts. The increase in the contents of carotenoids caused by the actions of experimental factors played an exceptional role in the mechanism of antioxidant protection that prevents destruction of chlorophyll and, accordingly, increases its amount in cells. Changes in the functioning of the photosynthetic apparatus of Ch. vulgaris affect the whole complex of metabolic transformation. Thus, the successful cultivation of chlorella, enriched with selenium and biogenic metals, is possible within seven days under the influence of 10 mg Se4+/dm3 and the above-mentioned concentration of metal ions.

A phyco-nanobionics biohybrid system for increased carotenoid accumulation inC. sorokinianaUUIND6

“…42 Any variation (Chl-a/Chl-b ratio) indicates a shift in the stoichiometric balance between the PS-II light-collecting complex and reaction centre complexes of both PS. 43…”

“…At 5 ppm HMBE-AgNPs, the microalgae demonstrated a greater Chl-a/Chl-b ratio in treated microalgal cells, which might be a marker of the NPs’ physiological reaction on the microalgal growth. 43 This is because ROS levels produced by AgNPs play an indispensable role for regulating photosynthesis and several other cellular activities, thus have the potential to attack chlorophyll, causing some Chl-b to change to Chl-a, resulting in increased Chl-a in microalgae cells. Additionally, a boost in Chl-a content may be due to acceptor side inhibition, whereas on a contrary hand, when AgNPs interact with ROS, they also exert both direct and indirect effects on algae under varied exposure conditions.…”

“…42 Any variation (Chl-a/Chl-b ratio) indicates a shift in the stoichiometric balance between the PS-II light-collecting complex and reaction centre complexes of both PS. 43 The experimental findings revealed that the concentration of Chl-a increased by 115% with an increase in AgNP concentration up to 5 ppm and then decreased at 10 ppm AgNP concentration while on the other hand, Chl-b was found to be in a lower concentration compared to Chl-a, but increased by 45% in all the tested concentrations (Fig. 6).…”